diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index 585ac1074..8796f8845 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -50,8 +50,6 @@ jobs:
         exclude:
           - os: centos
             build: agent2
-          - os: ubuntu
-            build: agent2
 
     runs-on: ubuntu-20.04
     steps:
diff --git a/README.md b/README.md
index 4259e114e..1985cc3b8 100644
--- a/README.md
+++ b/README.md
@@ -30,6 +30,7 @@ Please follow usage instructions of each Zabbix component image:
     > **Important information: Zabbix Docker Appliance has been decommissioned (except Red Hat edition) and will not be available for 3.0.31, 4.0.19, 4.4.7, 5.0.0 and newer releases. Please use a separate Docker images for each component instead of the all-in-one solution.**
 
 * [zabbix-agent](https://hub.docker.com/r/zabbix/zabbix-agent/) - Zabbix agent
+* [zabbix-agent2](https://hub.docker.com/r/zabbix/zabbix-agent2/) - Zabbix agent 2
 * [zabbix-server-mysql](https://hub.docker.com/r/zabbix/zabbix-server-mysql/) - Zabbix server with MySQL database support
 * [zabbix-server-pgsql](https://hub.docker.com/r/zabbix/zabbix-server-pgsql/) - Zabbix server with PostgreSQL database support
 * [zabbix-web-apache-mysql](https://hub.docker.com/r/zabbix/zabbix-web-apache-mysql/) - Zabbix web interface on Apache2 web server with MySQL database support
diff --git a/agent/alpine/README.md b/agent/alpine/README.md
index eb0a3f5b4..143597d19 100644
--- a/agent/alpine/README.md
+++ b/agent/alpine/README.md
@@ -14,10 +14,10 @@ Zabbix agent is deployed on a monitoring target to actively monitor local resour
 
 # Zabbix agent images
 
-These are the only official Zabbix agent Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix agent are:
+These are the only official Zabbix agent Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix agent are:
 
-    Zabbix agent 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix agent 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix agent 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix agent 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix agent 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix agent 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix agent 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/agent/alpine/docker-entrypoint.sh b/agent/alpine/docker-entrypoint.sh
index 9c8fc5791..4306b3d9a 100755
--- a/agent/alpine/docker-entrypoint.sh
+++ b/agent/alpine/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -136,7 +136,7 @@ prepare_zbx_agent_config() {
     update_config_var $ZBX_AGENT_CONFIG "LogRemoteCommands" "${ZBX_LOGREMOTECOMMANDS}"
 
     : ${ZBX_PASSIVE_ALLOW:="true"}
-    if [ "$ZBX_PASSIVE_ALLOW" == "true" ]; then
+    if [ "${ZBX_PASSIVE_ALLOW,,}" == "true" ]; then
         echo "** Using '$ZBX_PASSIVESERVERS' servers for passive checks"
         update_config_var $ZBX_AGENT_CONFIG "Server" "${ZBX_PASSIVESERVERS}"
     else
@@ -148,7 +148,7 @@ prepare_zbx_agent_config() {
     update_config_var $ZBX_AGENT_CONFIG "StartAgents" "${ZBX_STARTAGENTS}"
 
     : ${ZBX_ACTIVE_ALLOW:="true"}
-    if [ "$ZBX_ACTIVE_ALLOW" == "true" ]; then
+    if [ "${ZBX_ACTIVE_ALLOW,,}" == "true" ]; then
         echo "** Using '$ZBX_ACTIVESERVERS' servers for active checks"
         update_config_var $ZBX_AGENT_CONFIG "ServerActive" "${ZBX_ACTIVESERVERS}"
     else
diff --git a/agent/centos/README.md b/agent/centos/README.md
index eb0a3f5b4..143597d19 100644
--- a/agent/centos/README.md
+++ b/agent/centos/README.md
@@ -14,10 +14,10 @@ Zabbix agent is deployed on a monitoring target to actively monitor local resour
 
 # Zabbix agent images
 
-These are the only official Zabbix agent Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix agent are:
+These are the only official Zabbix agent Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix agent are:
 
-    Zabbix agent 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix agent 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix agent 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix agent 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix agent 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix agent 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix agent 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/agent/centos/docker-entrypoint.sh b/agent/centos/docker-entrypoint.sh
index 9c8fc5791..4306b3d9a 100755
--- a/agent/centos/docker-entrypoint.sh
+++ b/agent/centos/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -136,7 +136,7 @@ prepare_zbx_agent_config() {
     update_config_var $ZBX_AGENT_CONFIG "LogRemoteCommands" "${ZBX_LOGREMOTECOMMANDS}"
 
     : ${ZBX_PASSIVE_ALLOW:="true"}
-    if [ "$ZBX_PASSIVE_ALLOW" == "true" ]; then
+    if [ "${ZBX_PASSIVE_ALLOW,,}" == "true" ]; then
         echo "** Using '$ZBX_PASSIVESERVERS' servers for passive checks"
         update_config_var $ZBX_AGENT_CONFIG "Server" "${ZBX_PASSIVESERVERS}"
     else
@@ -148,7 +148,7 @@ prepare_zbx_agent_config() {
     update_config_var $ZBX_AGENT_CONFIG "StartAgents" "${ZBX_STARTAGENTS}"
 
     : ${ZBX_ACTIVE_ALLOW:="true"}
-    if [ "$ZBX_ACTIVE_ALLOW" == "true" ]; then
+    if [ "${ZBX_ACTIVE_ALLOW,,}" == "true" ]; then
         echo "** Using '$ZBX_ACTIVESERVERS' servers for active checks"
         update_config_var $ZBX_AGENT_CONFIG "ServerActive" "${ZBX_ACTIVESERVERS}"
     else
diff --git a/agent/rhel/README.md b/agent/rhel/README.md
index eb0a3f5b4..143597d19 100644
--- a/agent/rhel/README.md
+++ b/agent/rhel/README.md
@@ -14,10 +14,10 @@ Zabbix agent is deployed on a monitoring target to actively monitor local resour
 
 # Zabbix agent images
 
-These are the only official Zabbix agent Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix agent are:
+These are the only official Zabbix agent Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix agent are:
 
-    Zabbix agent 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix agent 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix agent 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix agent 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix agent 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix agent 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix agent 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/agent/rhel/docker-entrypoint.sh b/agent/rhel/docker-entrypoint.sh
index 9c8fc5791..4306b3d9a 100755
--- a/agent/rhel/docker-entrypoint.sh
+++ b/agent/rhel/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -136,7 +136,7 @@ prepare_zbx_agent_config() {
     update_config_var $ZBX_AGENT_CONFIG "LogRemoteCommands" "${ZBX_LOGREMOTECOMMANDS}"
 
     : ${ZBX_PASSIVE_ALLOW:="true"}
-    if [ "$ZBX_PASSIVE_ALLOW" == "true" ]; then
+    if [ "${ZBX_PASSIVE_ALLOW,,}" == "true" ]; then
         echo "** Using '$ZBX_PASSIVESERVERS' servers for passive checks"
         update_config_var $ZBX_AGENT_CONFIG "Server" "${ZBX_PASSIVESERVERS}"
     else
@@ -148,7 +148,7 @@ prepare_zbx_agent_config() {
     update_config_var $ZBX_AGENT_CONFIG "StartAgents" "${ZBX_STARTAGENTS}"
 
     : ${ZBX_ACTIVE_ALLOW:="true"}
-    if [ "$ZBX_ACTIVE_ALLOW" == "true" ]; then
+    if [ "${ZBX_ACTIVE_ALLOW,,}" == "true" ]; then
         echo "** Using '$ZBX_ACTIVESERVERS' servers for active checks"
         update_config_var $ZBX_AGENT_CONFIG "ServerActive" "${ZBX_ACTIVESERVERS}"
     else
diff --git a/agent/ubuntu/README.md b/agent/ubuntu/README.md
index eb0a3f5b4..143597d19 100644
--- a/agent/ubuntu/README.md
+++ b/agent/ubuntu/README.md
@@ -14,10 +14,10 @@ Zabbix agent is deployed on a monitoring target to actively monitor local resour
 
 # Zabbix agent images
 
-These are the only official Zabbix agent Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix agent are:
+These are the only official Zabbix agent Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix agent are:
 
-    Zabbix agent 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix agent 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix agent 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix agent 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix agent 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix agent 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix agent 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/agent/ubuntu/docker-entrypoint.sh b/agent/ubuntu/docker-entrypoint.sh
index 9c8fc5791..4306b3d9a 100755
--- a/agent/ubuntu/docker-entrypoint.sh
+++ b/agent/ubuntu/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -136,7 +136,7 @@ prepare_zbx_agent_config() {
     update_config_var $ZBX_AGENT_CONFIG "LogRemoteCommands" "${ZBX_LOGREMOTECOMMANDS}"
 
     : ${ZBX_PASSIVE_ALLOW:="true"}
-    if [ "$ZBX_PASSIVE_ALLOW" == "true" ]; then
+    if [ "${ZBX_PASSIVE_ALLOW,,}" == "true" ]; then
         echo "** Using '$ZBX_PASSIVESERVERS' servers for passive checks"
         update_config_var $ZBX_AGENT_CONFIG "Server" "${ZBX_PASSIVESERVERS}"
     else
@@ -148,7 +148,7 @@ prepare_zbx_agent_config() {
     update_config_var $ZBX_AGENT_CONFIG "StartAgents" "${ZBX_STARTAGENTS}"
 
     : ${ZBX_ACTIVE_ALLOW:="true"}
-    if [ "$ZBX_ACTIVE_ALLOW" == "true" ]; then
+    if [ "${ZBX_ACTIVE_ALLOW,,}" == "true" ]; then
         echo "** Using '$ZBX_ACTIVESERVERS' servers for active checks"
         update_config_var $ZBX_AGENT_CONFIG "ServerActive" "${ZBX_ACTIVESERVERS}"
     else
diff --git a/agent2/alpine/README.md b/agent2/alpine/README.md
index 0a2a5635b..f47326c08 100644
--- a/agent2/alpine/README.md
+++ b/agent2/alpine/README.md
@@ -21,7 +21,7 @@ These are the only official Zabbix agent 2 Docker images. They are based on Alpi
     Zabbix agent 2 5.0 (tags: alpine-5.0-latest, ubuntu-5.0-latest)
     Zabbix agent 2 5.0.* (tags: alpine-5.0.*, ubuntu-5.0.*)
     Zabbix agent 2 5.2 (tags: alpine-5.2-latest, ubuntu-5.2-latest, alpine-latest, ubuntu-latest, latest)
-    Zabbix agent 2 5.2.* (tags: alpine-5.2.*, ubuntu-5.0.*)
+    Zabbix agent 2 5.2.* (tags: alpine-5.2.*, ubuntu-5.2.*)
     Zabbix agent 2 5.4 (tags: alpine-trunk, ubuntu-trunk)
 
 Images are updated when new releases are published. The image with ``latest`` tag is based on Alpine Linux.
diff --git a/agent2/alpine/docker-entrypoint.sh b/agent2/alpine/docker-entrypoint.sh
index 5cad1e570..1476e10a4 100755
--- a/agent2/alpine/docker-entrypoint.sh
+++ b/agent2/alpine/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -136,7 +136,7 @@ prepare_zbx_agent_config() {
     update_config_var $ZBX_AGENT_CONFIG "LogRemoteCommands" "${ZBX_LOGREMOTECOMMANDS}"
 
     : ${ZBX_PASSIVE_ALLOW:="true"}
-    if [ "$ZBX_PASSIVE_ALLOW" == "true" ]; then
+    if [ "${ZBX_PASSIVE_ALLOW,,}" == "true" ]; then
         echo "** Using '$ZBX_PASSIVESERVERS' servers for passive checks"
         update_config_var $ZBX_AGENT_CONFIG "Server" "${ZBX_PASSIVESERVERS}"
     else
@@ -147,14 +147,14 @@ prepare_zbx_agent_config() {
     update_config_var $ZBX_AGENT_CONFIG "ListenIP" "${ZBX_LISTENIP}"
 
     : ${ZBX_ACTIVE_ALLOW:="true"}
-    if [ "$ZBX_ACTIVE_ALLOW" == "true" ]; then
+    if [ "${ZBX_ACTIVE_ALLOW,,}" == "true" ]; then
         echo "** Using '$ZBX_ACTIVESERVERS' servers for active checks"
         update_config_var $ZBX_AGENT_CONFIG "ServerActive" "${ZBX_ACTIVESERVERS}"
     else
         update_config_var $ZBX_AGENT_CONFIG "ServerActive"
     fi
 
-    if [ "$ZBX_ENABLESTATUSPORT" == "true" ]; then
+    if [ "${ZBX_ENABLEPERSISTENTBUFFER,,}" == "true" ]; then
         update_config_var $ZBX_AGENT_CONFIG "EnablePersistentBuffer" "1"
         update_config_var $ZBX_AGENT_CONFIG "PersistentBufferFile" "$ZABBIX_USER_HOME_DIR/buffer/"
         update_config_var $ZBX_AGENT_CONFIG "PersistentBufferPeriod" "${ZBX_PERSISTENTBUFFERPERIOD}"
@@ -162,7 +162,7 @@ prepare_zbx_agent_config() {
         update_config_var $ZBX_AGENT_CONFIG "EnablePersistentBuffer" "0"
     fi
 
-    if [ "$ZBX_ENABLESTATUSPORT" == "true" ]; then
+    if [ "${ZBX_ENABLESTATUSPORT,,}" == "true" ]; then
         update_config_var $ZBX_AGENT_CONFIG "StatusPort" "31999"
     fi
 
diff --git a/agent2/rhel/README.md b/agent2/rhel/README.md
index 0a2a5635b..f47326c08 100644
--- a/agent2/rhel/README.md
+++ b/agent2/rhel/README.md
@@ -21,7 +21,7 @@ These are the only official Zabbix agent 2 Docker images. They are based on Alpi
     Zabbix agent 2 5.0 (tags: alpine-5.0-latest, ubuntu-5.0-latest)
     Zabbix agent 2 5.0.* (tags: alpine-5.0.*, ubuntu-5.0.*)
     Zabbix agent 2 5.2 (tags: alpine-5.2-latest, ubuntu-5.2-latest, alpine-latest, ubuntu-latest, latest)
-    Zabbix agent 2 5.2.* (tags: alpine-5.2.*, ubuntu-5.0.*)
+    Zabbix agent 2 5.2.* (tags: alpine-5.2.*, ubuntu-5.2.*)
     Zabbix agent 2 5.4 (tags: alpine-trunk, ubuntu-trunk)
 
 Images are updated when new releases are published. The image with ``latest`` tag is based on Alpine Linux.
diff --git a/agent2/rhel/docker-entrypoint.sh b/agent2/rhel/docker-entrypoint.sh
index 5cad1e570..1476e10a4 100755
--- a/agent2/rhel/docker-entrypoint.sh
+++ b/agent2/rhel/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -136,7 +136,7 @@ prepare_zbx_agent_config() {
     update_config_var $ZBX_AGENT_CONFIG "LogRemoteCommands" "${ZBX_LOGREMOTECOMMANDS}"
 
     : ${ZBX_PASSIVE_ALLOW:="true"}
-    if [ "$ZBX_PASSIVE_ALLOW" == "true" ]; then
+    if [ "${ZBX_PASSIVE_ALLOW,,}" == "true" ]; then
         echo "** Using '$ZBX_PASSIVESERVERS' servers for passive checks"
         update_config_var $ZBX_AGENT_CONFIG "Server" "${ZBX_PASSIVESERVERS}"
     else
@@ -147,14 +147,14 @@ prepare_zbx_agent_config() {
     update_config_var $ZBX_AGENT_CONFIG "ListenIP" "${ZBX_LISTENIP}"
 
     : ${ZBX_ACTIVE_ALLOW:="true"}
-    if [ "$ZBX_ACTIVE_ALLOW" == "true" ]; then
+    if [ "${ZBX_ACTIVE_ALLOW,,}" == "true" ]; then
         echo "** Using '$ZBX_ACTIVESERVERS' servers for active checks"
         update_config_var $ZBX_AGENT_CONFIG "ServerActive" "${ZBX_ACTIVESERVERS}"
     else
         update_config_var $ZBX_AGENT_CONFIG "ServerActive"
     fi
 
-    if [ "$ZBX_ENABLESTATUSPORT" == "true" ]; then
+    if [ "${ZBX_ENABLEPERSISTENTBUFFER,,}" == "true" ]; then
         update_config_var $ZBX_AGENT_CONFIG "EnablePersistentBuffer" "1"
         update_config_var $ZBX_AGENT_CONFIG "PersistentBufferFile" "$ZABBIX_USER_HOME_DIR/buffer/"
         update_config_var $ZBX_AGENT_CONFIG "PersistentBufferPeriod" "${ZBX_PERSISTENTBUFFERPERIOD}"
@@ -162,7 +162,7 @@ prepare_zbx_agent_config() {
         update_config_var $ZBX_AGENT_CONFIG "EnablePersistentBuffer" "0"
     fi
 
-    if [ "$ZBX_ENABLESTATUSPORT" == "true" ]; then
+    if [ "${ZBX_ENABLESTATUSPORT,,}" == "true" ]; then
         update_config_var $ZBX_AGENT_CONFIG "StatusPort" "31999"
     fi
 
diff --git a/agent2/ubuntu/README.md b/agent2/ubuntu/README.md
index 0a2a5635b..f47326c08 100644
--- a/agent2/ubuntu/README.md
+++ b/agent2/ubuntu/README.md
@@ -21,7 +21,7 @@ These are the only official Zabbix agent 2 Docker images. They are based on Alpi
     Zabbix agent 2 5.0 (tags: alpine-5.0-latest, ubuntu-5.0-latest)
     Zabbix agent 2 5.0.* (tags: alpine-5.0.*, ubuntu-5.0.*)
     Zabbix agent 2 5.2 (tags: alpine-5.2-latest, ubuntu-5.2-latest, alpine-latest, ubuntu-latest, latest)
-    Zabbix agent 2 5.2.* (tags: alpine-5.2.*, ubuntu-5.0.*)
+    Zabbix agent 2 5.2.* (tags: alpine-5.2.*, ubuntu-5.2.*)
     Zabbix agent 2 5.4 (tags: alpine-trunk, ubuntu-trunk)
 
 Images are updated when new releases are published. The image with ``latest`` tag is based on Alpine Linux.
diff --git a/agent2/ubuntu/docker-entrypoint.sh b/agent2/ubuntu/docker-entrypoint.sh
index 5cad1e570..1476e10a4 100755
--- a/agent2/ubuntu/docker-entrypoint.sh
+++ b/agent2/ubuntu/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -136,7 +136,7 @@ prepare_zbx_agent_config() {
     update_config_var $ZBX_AGENT_CONFIG "LogRemoteCommands" "${ZBX_LOGREMOTECOMMANDS}"
 
     : ${ZBX_PASSIVE_ALLOW:="true"}
-    if [ "$ZBX_PASSIVE_ALLOW" == "true" ]; then
+    if [ "${ZBX_PASSIVE_ALLOW,,}" == "true" ]; then
         echo "** Using '$ZBX_PASSIVESERVERS' servers for passive checks"
         update_config_var $ZBX_AGENT_CONFIG "Server" "${ZBX_PASSIVESERVERS}"
     else
@@ -147,14 +147,14 @@ prepare_zbx_agent_config() {
     update_config_var $ZBX_AGENT_CONFIG "ListenIP" "${ZBX_LISTENIP}"
 
     : ${ZBX_ACTIVE_ALLOW:="true"}
-    if [ "$ZBX_ACTIVE_ALLOW" == "true" ]; then
+    if [ "${ZBX_ACTIVE_ALLOW,,}" == "true" ]; then
         echo "** Using '$ZBX_ACTIVESERVERS' servers for active checks"
         update_config_var $ZBX_AGENT_CONFIG "ServerActive" "${ZBX_ACTIVESERVERS}"
     else
         update_config_var $ZBX_AGENT_CONFIG "ServerActive"
     fi
 
-    if [ "$ZBX_ENABLESTATUSPORT" == "true" ]; then
+    if [ "${ZBX_ENABLEPERSISTENTBUFFER,,}" == "true" ]; then
         update_config_var $ZBX_AGENT_CONFIG "EnablePersistentBuffer" "1"
         update_config_var $ZBX_AGENT_CONFIG "PersistentBufferFile" "$ZABBIX_USER_HOME_DIR/buffer/"
         update_config_var $ZBX_AGENT_CONFIG "PersistentBufferPeriod" "${ZBX_PERSISTENTBUFFERPERIOD}"
@@ -162,7 +162,7 @@ prepare_zbx_agent_config() {
         update_config_var $ZBX_AGENT_CONFIG "EnablePersistentBuffer" "0"
     fi
 
-    if [ "$ZBX_ENABLESTATUSPORT" == "true" ]; then
+    if [ "${ZBX_ENABLESTATUSPORT,,}" == "true" ]; then
         update_config_var $ZBX_AGENT_CONFIG "StatusPort" "31999"
     fi
 
diff --git a/java-gateway/alpine/README.md b/java-gateway/alpine/README.md
index 37b25ba68..86edddf95 100644
--- a/java-gateway/alpine/README.md
+++ b/java-gateway/alpine/README.md
@@ -14,10 +14,10 @@ Zabbix Java Gateway performs native support for monitoring JMX applications. Jav
 
 # Zabbix Java Gateway images
 
-These are the only official Zabbix Java Gateway Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix Java Gateway are:
+These are the only official Zabbix Java Gateway Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix Java Gateway are:
 
-    Zabbix Java Gateway 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix Java Gateway 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix Java Gateway 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix Java Gateway 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix Java Gateway 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix Java Gateway 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix Java Gateway 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/java-gateway/alpine/docker-entrypoint.sh b/java-gateway/alpine/docker-entrypoint.sh
index ec5223733..01ac14cd1 100755
--- a/java-gateway/alpine/docker-entrypoint.sh
+++ b/java-gateway/alpine/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
diff --git a/java-gateway/centos/README.md b/java-gateway/centos/README.md
index 37b25ba68..86edddf95 100644
--- a/java-gateway/centos/README.md
+++ b/java-gateway/centos/README.md
@@ -14,10 +14,10 @@ Zabbix Java Gateway performs native support for monitoring JMX applications. Jav
 
 # Zabbix Java Gateway images
 
-These are the only official Zabbix Java Gateway Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix Java Gateway are:
+These are the only official Zabbix Java Gateway Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix Java Gateway are:
 
-    Zabbix Java Gateway 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix Java Gateway 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix Java Gateway 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix Java Gateway 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix Java Gateway 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix Java Gateway 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix Java Gateway 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/java-gateway/centos/docker-entrypoint.sh b/java-gateway/centos/docker-entrypoint.sh
index ec5223733..01ac14cd1 100755
--- a/java-gateway/centos/docker-entrypoint.sh
+++ b/java-gateway/centos/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
diff --git a/java-gateway/rhel/README.md b/java-gateway/rhel/README.md
index c4b0a4aa8..86edddf95 100644
--- a/java-gateway/rhel/README.md
+++ b/java-gateway/rhel/README.md
@@ -14,21 +14,25 @@ Zabbix Java Gateway performs native support for monitoring JMX applications. Jav
 
 # Zabbix Java Gateway images
 
-These are the only official Zabbix Java Gateway Docker images. They are based on Alpine Linux v3.9, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix Java Gateway are:
+These are the only official Zabbix Java Gateway Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix Java Gateway are:
 
-    Zabbix Java Gateway 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix Java Gateway 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
-    Zabbix Java Gateway 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest)
-    Zabbix Java Gateway 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*)
-    Zabbix Java Gateway 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest)
-    Zabbix Java Gateway 3.4.* (tags: alpine-3.4.*, ubuntu-3.4.*, centos-3.4.*)
+    Zabbix Java Gateway 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix Java Gateway 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
+    Zabbix Java Gateway 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
+    Zabbix Java Gateway 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
+    Zabbix Java Gateway 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
+    Zabbix Java Gateway 3.4.* (tags: alpine-3.4.*, ubuntu-3.4.*, centos-3.4.*) (unsupported)
     Zabbix Java Gateway 4.0 (tags: alpine-4.0-latest, ubuntu-4.0-latest, centos-4.0-latest)
     Zabbix Java Gateway 4.0.* (tags: alpine-4.0.*, ubuntu-4.0.*, centos-4.0.*)
-    Zabbix Java Gateway 4.2 (tags: alpine-4.2-latest, ubuntu-4.2-latest, centos-4.2-latest)
-    Zabbix Java Gateway 4.2.* (tags: alpine-4.2.*, ubuntu-4.2.*, centos-4.2.*)
-    Zabbix Java Gateway 4.4 (tags: alpine-4.4-latest, ubuntu-4.4-latest, centos-4.4-latest, alpine-latest, ubuntu-latest, centos-latest, latest)
-    Zabbix Java Gateway 4.4.* (tags: alpine-4.4.*, ubuntu-4.4.*, centos-4.4.*)
-    Zabbix Java Gateway 5.0 (tags: alpine-trunk, ubuntu-trunk, centos-trunk)
+    Zabbix Java Gateway 4.2 (tags: alpine-4.2-latest, ubuntu-4.2-latest, centos-4.2-latest) (unsupported)
+    Zabbix Java Gateway 4.2.* (tags: alpine-4.2.*, ubuntu-4.2.*, centos-4.2.*) (unsupported)
+    Zabbix Java Gateway 4.4 (tags: alpine-4.4-latest, ubuntu-4.4-latest, centos-4.4-latest) (unsupported)
+    Zabbix Java Gateway 4.4.* (tags: alpine-4.4.*, ubuntu-4.4.*, centos-4.4.*) (unsupported)
+    Zabbix Java Gateway 5.0 (tags: alpine-5.0-latest, ubuntu-5.0-latest, centos-5.0-latest)
+    Zabbix Java Gateway 5.0.* (tags: alpine-5.0.*, ubuntu-5.0.*, centos-5.0.*)
+    Zabbix Java Gateway 5.2 (tags: alpine-5.2-latest, ubuntu-5.2-latest, centos-5.2-latest, alpine-latest, ubuntu-latest, centos-latest, latest)
+    Zabbix Java Gateway 5.2.* (tags: alpine-5.2.*, ubuntu-5.2.*, centos-5.2.*)
+    Zabbix Java Gateway 5.4 (tags: alpine-trunk, ubuntu-trunk, centos-trunk)
 
 Images are updated when new releases are published. The image with ``latest`` tag is based on Alpine Linux.
 
@@ -76,6 +80,14 @@ This variable is used to specify timeout for outgoing connections. By default, v
 
 This variable is used to specify log level. By default, value is `info`. The variable allows next values: ``trace``, ``debug``, ``info``, ``want``, ``error``, ``all``, ``off``
 
+### `ZBX_PROPERTIES_FILE`
+
+Name of properties file. Can be used to set additional properties using a key-value format in such a way that they are not visible on a command line or to overwrite existing ones.
+
+### `ZABBIX_OPTIONS`
+
+Additional arguments for Zabbix Java Gateway. Useful to enable additional libraries and features.
+
 ## Allowed volumes for the Zabbix Java Gateway container
 
 ### ``/usr/sbin/zabbix_java/ext_lib``
@@ -110,7 +122,7 @@ Please see [the Docker installation documentation](https://docs.docker.com/insta
 
 ## Documentation
 
-Documentation for this image is stored in the [`java-gateway/` directory](https://github.com/zabbix/zabbix-docker/tree/3.0/java-gateway) of the [`zabbix/zabbix-docker` GitHub repo](https://github.com/zabbix/zabbix-docker/). Be sure to familiarize yourself with the [repository's `README.md` file](https://github.com/zabbix/zabbix-docker/blob/master/README.md) before attempting a pull request.
+Documentation for this image is stored in the [`java-gateway/` directory](https://github.com/zabbix/zabbix-docker/tree/current/java-gateway) of the [`zabbix/zabbix-docker` GitHub repo](https://github.com/zabbix/zabbix-docker/). Be sure to familiarize yourself with the [repository's `README.md` file](https://github.com/zabbix/zabbix-docker/blob/master/README.md) before attempting a pull request.
 
 ## Issues
 
diff --git a/java-gateway/rhel/docker-entrypoint.sh b/java-gateway/rhel/docker-entrypoint.sh
index ec5223733..01ac14cd1 100755
--- a/java-gateway/rhel/docker-entrypoint.sh
+++ b/java-gateway/rhel/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
diff --git a/java-gateway/ubuntu/README.md b/java-gateway/ubuntu/README.md
index 37b25ba68..86edddf95 100644
--- a/java-gateway/ubuntu/README.md
+++ b/java-gateway/ubuntu/README.md
@@ -14,10 +14,10 @@ Zabbix Java Gateway performs native support for monitoring JMX applications. Jav
 
 # Zabbix Java Gateway images
 
-These are the only official Zabbix Java Gateway Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix Java Gateway are:
+These are the only official Zabbix Java Gateway Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix Java Gateway are:
 
-    Zabbix Java Gateway 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix Java Gateway 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix Java Gateway 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix Java Gateway 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix Java Gateway 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix Java Gateway 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix Java Gateway 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/java-gateway/ubuntu/docker-entrypoint.sh b/java-gateway/ubuntu/docker-entrypoint.sh
index ec5223733..01ac14cd1 100755
--- a/java-gateway/ubuntu/docker-entrypoint.sh
+++ b/java-gateway/ubuntu/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
diff --git a/proxy-mysql/alpine/README.md b/proxy-mysql/alpine/README.md
index 4923c1b05..4f833d846 100644
--- a/proxy-mysql/alpine/README.md
+++ b/proxy-mysql/alpine/README.md
@@ -14,10 +14,10 @@ Zabbix proxy is a process that may collect monitoring data from one or more moni
 
 # Zabbix proxy images
 
-These are the only official Zabbix proxy Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix proxy are:
+These are the only official Zabbix proxy Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix proxy are:
 
-    Zabbix proxy 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix proxy 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix proxy 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix proxy 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix proxy 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix proxy 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix proxy 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/proxy-mysql/alpine/docker-entrypoint.sh b/proxy-mysql/alpine/docker-entrypoint.sh
index c92026ec0..59e192bf4 100755
--- a/proxy-mysql/alpine/docker-entrypoint.sh
+++ b/proxy-mysql/alpine/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -150,17 +150,17 @@ check_variables_mysql() {
 
     file_env MYSQL_ROOT_PASSWORD
 
-    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD}" == "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD,,}" == "true" ]; then
         echo "**** Impossible to use MySQL server because of unknown Zabbix user and random 'root' password"
         exit 1
     fi
 
-    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" != "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" != "true" ]; then
         echo "*** Impossible to use MySQL server because 'root' password is not defined and it is not empty"
         exit 1
     fi
 
-    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
+    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
         USE_DB_ROOT_USER=true
         DB_SERVER_ROOT_USER="root"
         DB_SERVER_ROOT_PASS=${MYSQL_ROOT_PASSWORD:-""}
@@ -170,7 +170,7 @@ check_variables_mysql() {
 
     # If root password is not specified use provided credentials
     DB_SERVER_ROOT_USER=${DB_SERVER_ROOT_USER:-${MYSQL_USER}}
-    [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
+    [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
     DB_SERVER_ZBX_USER=${MYSQL_USER:-"zabbix"}
     DB_SERVER_ZBX_PASS=${MYSQL_PASSWORD:-"zabbix"}
 
@@ -208,7 +208,7 @@ check_db_connect_mysql() {
     echo "* DB_SERVER_HOST: ${DB_SERVER_HOST}"
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -368,7 +368,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "StartHTTPPollers" "${ZBX_STARTHTTPPOLLERS}"
 
     : ${ZBX_JAVAGATEWAY_ENABLE:="false"}
-    if [ "${ZBX_JAVAGATEWAY_ENABLE}" == "true" ]; then
+    if [ "${ZBX_JAVAGATEWAY_ENABLE,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "JavaGateway" "${ZBX_JAVAGATEWAY:-"zabbix-java-gateway"}"
         update_config_var $ZBX_CONFIG "JavaGatewayPort" "${ZBX_JAVAGATEWAYPORT}"
         update_config_var $ZBX_CONFIG "StartJavaPollers" "${ZBX_STARTJAVAPOLLERS:-"5"}"
@@ -385,7 +385,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "VMwareTimeout" "${ZBX_VMWARETIMEOUT}"
 
     : ${ZBX_ENABLE_SNMP_TRAPS:="false"}
-    if [ "${ZBX_ENABLE_SNMP_TRAPS}" == "true" ]; then
+    if [ "${ZBX_ENABLE_SNMP_TRAPS,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "SNMPTrapperFile" "${ZABBIX_USER_HOME_DIR}/snmptraps/snmptraps.log"
         update_config_var $ZBX_CONFIG "StartSNMPTrapper" "1"
     else
diff --git a/proxy-mysql/centos/README.md b/proxy-mysql/centos/README.md
index 4923c1b05..4f833d846 100644
--- a/proxy-mysql/centos/README.md
+++ b/proxy-mysql/centos/README.md
@@ -14,10 +14,10 @@ Zabbix proxy is a process that may collect monitoring data from one or more moni
 
 # Zabbix proxy images
 
-These are the only official Zabbix proxy Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix proxy are:
+These are the only official Zabbix proxy Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix proxy are:
 
-    Zabbix proxy 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix proxy 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix proxy 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix proxy 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix proxy 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix proxy 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix proxy 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/proxy-mysql/centos/docker-entrypoint.sh b/proxy-mysql/centos/docker-entrypoint.sh
index 3d6bfd48c..ea53d067c 100755
--- a/proxy-mysql/centos/docker-entrypoint.sh
+++ b/proxy-mysql/centos/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -150,17 +150,17 @@ check_variables_mysql() {
 
     file_env MYSQL_ROOT_PASSWORD
 
-    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD}" == "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD,,}" == "true" ]; then
         echo "**** Impossible to use MySQL server because of unknown Zabbix user and random 'root' password"
         exit 1
     fi
 
-    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" != "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" != "true" ]; then
         echo "*** Impossible to use MySQL server because 'root' password is not defined and it is not empty"
         exit 1
     fi
 
-    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
+    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
         USE_DB_ROOT_USER=true
         DB_SERVER_ROOT_USER="root"
         DB_SERVER_ROOT_PASS=${MYSQL_ROOT_PASSWORD:-""}
@@ -170,7 +170,7 @@ check_variables_mysql() {
 
     # If root password is not specified use provided credentials
     DB_SERVER_ROOT_USER=${DB_SERVER_ROOT_USER:-${MYSQL_USER}}
-    [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
+    [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
     DB_SERVER_ZBX_USER=${MYSQL_USER:-"zabbix"}
     DB_SERVER_ZBX_PASS=${MYSQL_PASSWORD:-"zabbix"}
 
@@ -205,7 +205,7 @@ check_db_connect_mysql() {
     echo "* DB_SERVER_HOST: ${DB_SERVER_HOST}"
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -365,7 +365,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "StartHTTPPollers" "${ZBX_STARTHTTPPOLLERS}"
 
     : ${ZBX_JAVAGATEWAY_ENABLE:="false"}
-    if [ "${ZBX_JAVAGATEWAY_ENABLE}" == "true" ]; then
+    if [ "${ZBX_JAVAGATEWAY_ENABLE,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "JavaGateway" "${ZBX_JAVAGATEWAY:-"zabbix-java-gateway"}"
         update_config_var $ZBX_CONFIG "JavaGatewayPort" "${ZBX_JAVAGATEWAYPORT}"
         update_config_var $ZBX_CONFIG "StartJavaPollers" "${ZBX_STARTJAVAPOLLERS:-"5"}"
@@ -382,7 +382,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "VMwareTimeout" "${ZBX_VMWARETIMEOUT}"
 
     : ${ZBX_ENABLE_SNMP_TRAPS:="false"}
-    if [ "${ZBX_ENABLE_SNMP_TRAPS}" == "true" ]; then
+    if [ "${ZBX_ENABLE_SNMP_TRAPS,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "SNMPTrapperFile" "${ZABBIX_USER_HOME_DIR}/snmptraps/snmptraps.log"
         update_config_var $ZBX_CONFIG "StartSNMPTrapper" "1"
     else
diff --git a/proxy-mysql/rhel/docker-entrypoint.sh b/proxy-mysql/rhel/docker-entrypoint.sh
index 49e1cb0c1..c2bbf252e 100755
--- a/proxy-mysql/rhel/docker-entrypoint.sh
+++ b/proxy-mysql/rhel/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -150,17 +150,17 @@ check_variables_mysql() {
 
     file_env MYSQL_ROOT_PASSWORD
 
-    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD}" == "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD,,}" == "true" ]; then
         echo "**** Impossible to use MySQL server because of unknown Zabbix user and random 'root' password"
         exit 1
     fi
 
-    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" != "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" != "true" ]; then
         echo "*** Impossible to use MySQL server because 'root' password is not defined and it is not empty"
         exit 1
     fi
 
-    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
+    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
         USE_DB_ROOT_USER=true
         DB_SERVER_ROOT_USER="root"
         DB_SERVER_ROOT_PASS=${MYSQL_ROOT_PASSWORD:-""}
@@ -170,7 +170,7 @@ check_variables_mysql() {
 
     # If root password is not specified use provided credentials
     DB_SERVER_ROOT_USER=${DB_SERVER_ROOT_USER:-${MYSQL_USER}}
-    [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
+    [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
     DB_SERVER_ZBX_USER=${MYSQL_USER:-"zabbix"}
     DB_SERVER_ZBX_PASS=${MYSQL_PASSWORD:-"zabbix"}
 
@@ -205,7 +205,7 @@ check_db_connect_mysql() {
     echo "* DB_SERVER_HOST: ${DB_SERVER_HOST}"
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -366,7 +366,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "StartHTTPPollers" "${ZBX_STARTHTTPPOLLERS}"
 
     : ${ZBX_JAVAGATEWAY_ENABLE:="false"}
-    if [ "${ZBX_JAVAGATEWAY_ENABLE}" == "true" ]; then
+    if [ "${ZBX_JAVAGATEWAY_ENABLE,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "JavaGateway" "${ZBX_JAVAGATEWAY:-"zabbix-java-gateway"}"
         update_config_var $ZBX_CONFIG "JavaGatewayPort" "${ZBX_JAVAGATEWAYPORT}"
         update_config_var $ZBX_CONFIG "StartJavaPollers" "${ZBX_STARTJAVAPOLLERS:-"5"}"
@@ -383,7 +383,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "VMwareTimeout" "${ZBX_VMWARETIMEOUT}"
 
     : ${ZBX_ENABLE_SNMP_TRAPS:="false"}
-    if [ "${ZBX_ENABLE_SNMP_TRAPS}" == "true" ]; then
+    if [ "${ZBX_ENABLE_SNMP_TRAPS,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "SNMPTrapperFile" "${ZABBIX_USER_HOME_DIR}/snmptraps/snmptraps.log"
         update_config_var $ZBX_CONFIG "StartSNMPTrapper" "1"
     else
diff --git a/proxy-mysql/ubuntu/README.md b/proxy-mysql/ubuntu/README.md
index 4923c1b05..4f833d846 100644
--- a/proxy-mysql/ubuntu/README.md
+++ b/proxy-mysql/ubuntu/README.md
@@ -14,10 +14,10 @@ Zabbix proxy is a process that may collect monitoring data from one or more moni
 
 # Zabbix proxy images
 
-These are the only official Zabbix proxy Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix proxy are:
+These are the only official Zabbix proxy Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix proxy are:
 
-    Zabbix proxy 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix proxy 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix proxy 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix proxy 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix proxy 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix proxy 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix proxy 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/proxy-mysql/ubuntu/docker-entrypoint.sh b/proxy-mysql/ubuntu/docker-entrypoint.sh
index 214cea411..2f7ade336 100755
--- a/proxy-mysql/ubuntu/docker-entrypoint.sh
+++ b/proxy-mysql/ubuntu/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -150,17 +150,17 @@ check_variables_mysql() {
 
     file_env MYSQL_ROOT_PASSWORD
 
-    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD}" == "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD,,}" == "true" ]; then
         echo "**** Impossible to use MySQL server because of unknown Zabbix user and random 'root' password"
         exit 1
     fi
 
-    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" != "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" != "true" ]; then
         echo "*** Impossible to use MySQL server because 'root' password is not defined and it is not empty"
         exit 1
     fi
 
-    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
+    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
         USE_DB_ROOT_USER=true
         DB_SERVER_ROOT_USER="root"
         DB_SERVER_ROOT_PASS=${MYSQL_ROOT_PASSWORD:-""}
@@ -170,7 +170,7 @@ check_variables_mysql() {
 
     # If root password is not specified use provided credentials
     DB_SERVER_ROOT_USER=${DB_SERVER_ROOT_USER:-${MYSQL_USER}}
-    [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
+    [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
     DB_SERVER_ZBX_USER=${MYSQL_USER:-"zabbix"}
     DB_SERVER_ZBX_PASS=${MYSQL_PASSWORD:-"zabbix"}
 
@@ -205,7 +205,7 @@ check_db_connect_mysql() {
     echo "* DB_SERVER_HOST: ${DB_SERVER_HOST}"
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -365,7 +365,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "StartHTTPPollers" "${ZBX_STARTHTTPPOLLERS}"
 
     : ${ZBX_JAVAGATEWAY_ENABLE:="false"}
-    if [ "${ZBX_JAVAGATEWAY_ENABLE}" == "true" ]; then
+    if [ "${ZBX_JAVAGATEWAY_ENABLE,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "JavaGateway" "${ZBX_JAVAGATEWAY:-"zabbix-java-gateway"}"
         update_config_var $ZBX_CONFIG "JavaGatewayPort" "${ZBX_JAVAGATEWAYPORT}"
         update_config_var $ZBX_CONFIG "StartJavaPollers" "${ZBX_STARTJAVAPOLLERS:-"5"}"
@@ -382,7 +382,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "VMwareTimeout" "${ZBX_VMWARETIMEOUT}"
 
     : ${ZBX_ENABLE_SNMP_TRAPS:="false"}
-    if [ "${ZBX_ENABLE_SNMP_TRAPS}" == "true" ]; then
+    if [ "${ZBX_ENABLE_SNMP_TRAPS,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "SNMPTrapperFile" "${ZABBIX_USER_HOME_DIR}/snmptraps/snmptraps.log"
         update_config_var $ZBX_CONFIG "StartSNMPTrapper" "1"
     else
diff --git a/proxy-sqlite3/alpine/README.md b/proxy-sqlite3/alpine/README.md
index e7878a09b..887e93f10 100644
--- a/proxy-sqlite3/alpine/README.md
+++ b/proxy-sqlite3/alpine/README.md
@@ -14,10 +14,10 @@ Zabbix proxy is a process that may collect monitoring data from one or more moni
 
 # Zabbix proxy images
 
-These are the only official Zabbix proxy Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix proxy are:
+These are the only official Zabbix proxy Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix proxy are:
 
-    Zabbix proxy 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix proxy 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix proxy 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix proxy 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix proxy 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix proxy 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix proxy 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/proxy-sqlite3/alpine/docker-entrypoint.sh b/proxy-sqlite3/alpine/docker-entrypoint.sh
index bce53c036..42215e3e7 100755
--- a/proxy-sqlite3/alpine/docker-entrypoint.sh
+++ b/proxy-sqlite3/alpine/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -162,7 +162,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "StartHTTPPollers" "${ZBX_STARTHTTPPOLLERS}"
 
     : ${ZBX_JAVAGATEWAY_ENABLE:="false"}
-    if [ "${ZBX_JAVAGATEWAY_ENABLE}" == "true" ]; then
+    if [ "${ZBX_JAVAGATEWAY_ENABLE,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "JavaGateway" "${ZBX_JAVAGATEWAY:-"zabbix-java-gateway"}"
         update_config_var $ZBX_CONFIG "JavaGatewayPort" "${ZBX_JAVAGATEWAYPORT}"
         update_config_var $ZBX_CONFIG "StartJavaPollers" "${ZBX_STARTJAVAPOLLERS:-"5"}"
@@ -179,7 +179,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "VMwareTimeout" "${ZBX_VMWARETIMEOUT}"
 
     : ${ZBX_ENABLE_SNMP_TRAPS:="false"}
-    if [ "${ZBX_ENABLE_SNMP_TRAPS}" == "true" ]; then
+    if [ "${ZBX_ENABLE_SNMP_TRAPS,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "SNMPTrapperFile" "${ZABBIX_USER_HOME_DIR}/snmptraps/snmptraps.log"
         update_config_var $ZBX_CONFIG "StartSNMPTrapper" "1"
     else
diff --git a/proxy-sqlite3/centos/README.md b/proxy-sqlite3/centos/README.md
index e7878a09b..887e93f10 100644
--- a/proxy-sqlite3/centos/README.md
+++ b/proxy-sqlite3/centos/README.md
@@ -14,10 +14,10 @@ Zabbix proxy is a process that may collect monitoring data from one or more moni
 
 # Zabbix proxy images
 
-These are the only official Zabbix proxy Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix proxy are:
+These are the only official Zabbix proxy Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix proxy are:
 
-    Zabbix proxy 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix proxy 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix proxy 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix proxy 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix proxy 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix proxy 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix proxy 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/proxy-sqlite3/centos/docker-entrypoint.sh b/proxy-sqlite3/centos/docker-entrypoint.sh
index bce53c036..42215e3e7 100755
--- a/proxy-sqlite3/centos/docker-entrypoint.sh
+++ b/proxy-sqlite3/centos/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -162,7 +162,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "StartHTTPPollers" "${ZBX_STARTHTTPPOLLERS}"
 
     : ${ZBX_JAVAGATEWAY_ENABLE:="false"}
-    if [ "${ZBX_JAVAGATEWAY_ENABLE}" == "true" ]; then
+    if [ "${ZBX_JAVAGATEWAY_ENABLE,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "JavaGateway" "${ZBX_JAVAGATEWAY:-"zabbix-java-gateway"}"
         update_config_var $ZBX_CONFIG "JavaGatewayPort" "${ZBX_JAVAGATEWAYPORT}"
         update_config_var $ZBX_CONFIG "StartJavaPollers" "${ZBX_STARTJAVAPOLLERS:-"5"}"
@@ -179,7 +179,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "VMwareTimeout" "${ZBX_VMWARETIMEOUT}"
 
     : ${ZBX_ENABLE_SNMP_TRAPS:="false"}
-    if [ "${ZBX_ENABLE_SNMP_TRAPS}" == "true" ]; then
+    if [ "${ZBX_ENABLE_SNMP_TRAPS,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "SNMPTrapperFile" "${ZABBIX_USER_HOME_DIR}/snmptraps/snmptraps.log"
         update_config_var $ZBX_CONFIG "StartSNMPTrapper" "1"
     else
diff --git a/proxy-sqlite3/rhel/README.md b/proxy-sqlite3/rhel/README.md
index 77c514388..887e93f10 100644
--- a/proxy-sqlite3/rhel/README.md
+++ b/proxy-sqlite3/rhel/README.md
@@ -14,22 +14,24 @@ Zabbix proxy is a process that may collect monitoring data from one or more moni
 
 # Zabbix proxy images
 
-These are the only official Zabbix proxy Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix proxy are:
+These are the only official Zabbix proxy Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix proxy are:
 
-    Zabbix proxy 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix proxy 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
-    Zabbix proxy 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2.*) (unsupported)
+    Zabbix proxy 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix proxy 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
+    Zabbix proxy 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix proxy 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
-    Zabbix proxy 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4.*) (unsupported)
+    Zabbix proxy 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
     Zabbix proxy 3.4.* (tags: alpine-3.4.*, ubuntu-3.4.*, centos-3.4.*) (unsupported)
     Zabbix proxy 4.0 (tags: alpine-4.0-latest, ubuntu-4.0-latest, centos-4.0-latest)
     Zabbix proxy 4.0.* (tags: alpine-4.0.*, ubuntu-4.0.*, centos-4.0.*)
-    Zabbix proxy 4.2 (tags: alpine-4.2-latest, ubuntu-4.2-latest, centos-4.2.*) (unsupported)
+    Zabbix proxy 4.2 (tags: alpine-4.2-latest, ubuntu-4.2-latest, centos-4.2-latest) (unsupported)
     Zabbix proxy 4.2.* (tags: alpine-4.2.*, ubuntu-4.2.*, centos-4.2.*) (unsupported)
     Zabbix proxy 4.4 (tags: alpine-4.4-latest, ubuntu-4.4-latest, centos-4.4-latest) (unsupported)
     Zabbix proxy 4.4.* (tags: alpine-4.4.*, ubuntu-4.4.*, centos-4.4.*) (unsupported)
-    Zabbix proxy 5.0 (tags: alpine-5.0-latest, ubuntu-5.0-latest, centos-5.0-latest, alpine-latest, ubuntu-latest, centos-latest, latest)
+    Zabbix proxy 5.0 (tags: alpine-5.0-latest, ubuntu-5.0-latest, centos-5.0-latest)
     Zabbix proxy 5.0.* (tags: alpine-5.0.*, ubuntu-5.0.*, centos-5.0.*)
+    Zabbix proxy 5.2 (tags: alpine-5.2-latest, ubuntu-5.2-latest, centos-5.2-latest, alpine-latest, ubuntu-latest, centos-latest, latest)
+    Zabbix proxy 5.2.* (tags: alpine-5.2.*, ubuntu-5.2.*, centos-5.2.*)
     Zabbix proxy 5.2 (tags: alpine-trunk, ubuntu-trunk, centos-trunk)
 
 Images are updated when new releases are published. The image with ``latest`` tag is based on Alpine Linux.
@@ -123,6 +125,9 @@ The variable enable communication with Zabbix Java Gateway to collect Java relat
 Additionally the image allows to specify many other environment variables listed below:
 
 ```
+ZBX_VAULTDBPATH= # Available since 5.2.0
+ZBX_VAULTURL=https://127.0.0.1:8200 # Available since 5.2.0
+VAULT_TOKEN= # Available since 5.2.0
 ZBX_ENABLEREMOTECOMMANDS=0 # Available since 3.4.0
 ZBX_LOGREMOTECOMMANDS=0 # Available since 3.4.0
 ZBX_SOURCEIP=
diff --git a/proxy-sqlite3/rhel/docker-entrypoint.sh b/proxy-sqlite3/rhel/docker-entrypoint.sh
index bce53c036..42215e3e7 100755
--- a/proxy-sqlite3/rhel/docker-entrypoint.sh
+++ b/proxy-sqlite3/rhel/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -162,7 +162,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "StartHTTPPollers" "${ZBX_STARTHTTPPOLLERS}"
 
     : ${ZBX_JAVAGATEWAY_ENABLE:="false"}
-    if [ "${ZBX_JAVAGATEWAY_ENABLE}" == "true" ]; then
+    if [ "${ZBX_JAVAGATEWAY_ENABLE,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "JavaGateway" "${ZBX_JAVAGATEWAY:-"zabbix-java-gateway"}"
         update_config_var $ZBX_CONFIG "JavaGatewayPort" "${ZBX_JAVAGATEWAYPORT}"
         update_config_var $ZBX_CONFIG "StartJavaPollers" "${ZBX_STARTJAVAPOLLERS:-"5"}"
@@ -179,7 +179,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "VMwareTimeout" "${ZBX_VMWARETIMEOUT}"
 
     : ${ZBX_ENABLE_SNMP_TRAPS:="false"}
-    if [ "${ZBX_ENABLE_SNMP_TRAPS}" == "true" ]; then
+    if [ "${ZBX_ENABLE_SNMP_TRAPS,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "SNMPTrapperFile" "${ZABBIX_USER_HOME_DIR}/snmptraps/snmptraps.log"
         update_config_var $ZBX_CONFIG "StartSNMPTrapper" "1"
     else
diff --git a/proxy-sqlite3/ubuntu/README.md b/proxy-sqlite3/ubuntu/README.md
index e7878a09b..887e93f10 100644
--- a/proxy-sqlite3/ubuntu/README.md
+++ b/proxy-sqlite3/ubuntu/README.md
@@ -14,10 +14,10 @@ Zabbix proxy is a process that may collect monitoring data from one or more moni
 
 # Zabbix proxy images
 
-These are the only official Zabbix proxy Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix proxy are:
+These are the only official Zabbix proxy Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix proxy are:
 
-    Zabbix proxy 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix proxy 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix proxy 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix proxy 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix proxy 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix proxy 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix proxy 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/proxy-sqlite3/ubuntu/docker-entrypoint.sh b/proxy-sqlite3/ubuntu/docker-entrypoint.sh
index 12d18e685..cbc0ac48c 100755
--- a/proxy-sqlite3/ubuntu/docker-entrypoint.sh
+++ b/proxy-sqlite3/ubuntu/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -162,7 +162,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "StartHTTPPollers" "${ZBX_STARTHTTPPOLLERS}"
 
     : ${ZBX_JAVAGATEWAY_ENABLE:="false"}
-    if [ "${ZBX_JAVAGATEWAY_ENABLE}" == "true" ]; then
+    if [ "${ZBX_JAVAGATEWAY_ENABLE,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "JavaGateway" "${ZBX_JAVAGATEWAY:-"zabbix-java-gateway"}"
         update_config_var $ZBX_CONFIG "JavaGatewayPort" "${ZBX_JAVAGATEWAYPORT}"
         update_config_var $ZBX_CONFIG "StartJavaPollers" "${ZBX_STARTJAVAPOLLERS:-"5"}"
@@ -179,7 +179,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "VMwareTimeout" "${ZBX_VMWARETIMEOUT}"
 
     : ${ZBX_ENABLE_SNMP_TRAPS:="false"}
-    if [ "${ZBX_ENABLE_SNMP_TRAPS}" == "true" ]; then
+    if [ "${ZBX_ENABLE_SNMP_TRAPS,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "SNMPTrapperFile" "${ZABBIX_USER_HOME_DIR}/snmptraps/snmptraps.log"
         update_config_var $ZBX_CONFIG "StartSNMPTrapper" "1"
     else
diff --git a/server-mysql/alpine/README.md b/server-mysql/alpine/README.md
index d19c3cd8e..f672cd64b 100644
--- a/server-mysql/alpine/README.md
+++ b/server-mysql/alpine/README.md
@@ -16,10 +16,10 @@ The server performs the polling and trapping of data, it calculates triggers, se
 
 # Zabbix server images
 
-These are the only official Zabbix server Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix server are:
+These are the only official Zabbix server Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix server are:
 
-    Zabbix server 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix server 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix server 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix server 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix server 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix server 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix server 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/server-mysql/alpine/docker-entrypoint.sh b/server-mysql/alpine/docker-entrypoint.sh
index 6f82044e0..f4707e4d0 100755
--- a/server-mysql/alpine/docker-entrypoint.sh
+++ b/server-mysql/alpine/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -145,17 +145,17 @@ check_variables_mysql() {
 
     file_env MYSQL_ROOT_PASSWORD
 
-    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD}" == "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD,,}" == "true" ]; then
         echo "**** Impossible to use MySQL server because of unknown Zabbix user and random 'root' password"
         exit 1
     fi
 
-    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" != "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" != "true" ]; then
         echo "*** Impossible to use MySQL server because 'root' password is not defined and it is not empty"
         exit 1
     fi
 
-    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
+    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
         USE_DB_ROOT_USER=true
         DB_SERVER_ROOT_USER="root"
         DB_SERVER_ROOT_PASS=${MYSQL_ROOT_PASSWORD:-""}
@@ -165,7 +165,7 @@ check_variables_mysql() {
 
     # If root password is not specified use provided credentials
     : ${DB_SERVER_ROOT_USER:=${MYSQL_USER}}
-    [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
+    [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
     DB_SERVER_ZBX_USER=${MYSQL_USER:-"zabbix"}
     DB_SERVER_ZBX_PASS=${MYSQL_PASSWORD:-"zabbix"}
 
@@ -203,7 +203,7 @@ check_db_connect_mysql() {
     echo "* DB_SERVER_HOST: ${DB_SERVER_HOST}"
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -355,7 +355,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "StartLLDProcessors" "${ZBX_STARTLLDPROCESSORS}"
 
     : ${ZBX_JAVAGATEWAY_ENABLE:="false"}
-    if [ "${ZBX_JAVAGATEWAY_ENABLE}" == "true" ]; then
+    if [ "${ZBX_JAVAGATEWAY_ENABLE,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "JavaGateway" "${ZBX_JAVAGATEWAY:-"zabbix-java-gateway"}"
         update_config_var $ZBX_CONFIG "JavaGatewayPort" "${ZBX_JAVAGATEWAYPORT}"
         update_config_var $ZBX_CONFIG "StartJavaPollers" "${ZBX_STARTJAVAPOLLERS:-"5"}"
@@ -372,7 +372,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "VMwareTimeout" "${ZBX_VMWARETIMEOUT}"
 
     : ${ZBX_ENABLE_SNMP_TRAPS:="false"}
-    if [ "${ZBX_ENABLE_SNMP_TRAPS}" == "true" ]; then
+    if [ "${ZBX_ENABLE_SNMP_TRAPS,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "SNMPTrapperFile" "${ZABBIX_USER_HOME_DIR}/snmptraps/snmptraps.log"
         update_config_var $ZBX_CONFIG "StartSNMPTrapper" "1"
     else
diff --git a/server-mysql/centos/README.md b/server-mysql/centos/README.md
index d19c3cd8e..f672cd64b 100644
--- a/server-mysql/centos/README.md
+++ b/server-mysql/centos/README.md
@@ -16,10 +16,10 @@ The server performs the polling and trapping of data, it calculates triggers, se
 
 # Zabbix server images
 
-These are the only official Zabbix server Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix server are:
+These are the only official Zabbix server Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix server are:
 
-    Zabbix server 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix server 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix server 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix server 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix server 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix server 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix server 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/server-mysql/centos/docker-entrypoint.sh b/server-mysql/centos/docker-entrypoint.sh
index b00ebcbf5..85ea82c46 100755
--- a/server-mysql/centos/docker-entrypoint.sh
+++ b/server-mysql/centos/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -145,17 +145,17 @@ check_variables_mysql() {
 
     file_env MYSQL_ROOT_PASSWORD
 
-    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD}" == "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD,,}" == "true" ]; then
         echo "**** Impossible to use MySQL server because of unknown Zabbix user and random 'root' password"
         exit 1
     fi
 
-    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" != "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" != "true" ]; then
         echo "*** Impossible to use MySQL server because 'root' password is not defined and it is not empty"
         exit 1
     fi
 
-    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
+    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
         USE_DB_ROOT_USER=true
         DB_SERVER_ROOT_USER="root"
         DB_SERVER_ROOT_PASS=${MYSQL_ROOT_PASSWORD:-""}
@@ -165,7 +165,7 @@ check_variables_mysql() {
 
     # If root password is not specified use provided credentials
     : ${DB_SERVER_ROOT_USER:=${MYSQL_USER}}
-    [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
+    [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
     DB_SERVER_ZBX_USER=${MYSQL_USER:-"zabbix"}
     DB_SERVER_ZBX_PASS=${MYSQL_PASSWORD:-"zabbix"}
 
@@ -200,7 +200,7 @@ check_db_connect_mysql() {
     echo "* DB_SERVER_HOST: ${DB_SERVER_HOST}"
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -352,7 +352,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "StartLLDProcessors" "${ZBX_STARTLLDPROCESSORS}"
 
     : ${ZBX_JAVAGATEWAY_ENABLE:="false"}
-    if [ "${ZBX_JAVAGATEWAY_ENABLE}" == "true" ]; then
+    if [ "${ZBX_JAVAGATEWAY_ENABLE,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "JavaGateway" "${ZBX_JAVAGATEWAY:-"zabbix-java-gateway"}"
         update_config_var $ZBX_CONFIG "JavaGatewayPort" "${ZBX_JAVAGATEWAYPORT}"
         update_config_var $ZBX_CONFIG "StartJavaPollers" "${ZBX_STARTJAVAPOLLERS:-"5"}"
@@ -369,7 +369,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "VMwareTimeout" "${ZBX_VMWARETIMEOUT}"
 
     : ${ZBX_ENABLE_SNMP_TRAPS:="false"}
-    if [ "${ZBX_ENABLE_SNMP_TRAPS}" == "true" ]; then
+    if [ "${ZBX_ENABLE_SNMP_TRAPS,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "SNMPTrapperFile" "${ZABBIX_USER_HOME_DIR}/snmptraps/snmptraps.log"
         update_config_var $ZBX_CONFIG "StartSNMPTrapper" "1"
     else
diff --git a/server-mysql/rhel/README.md b/server-mysql/rhel/README.md
index 060b0fe15..f672cd64b 100644
--- a/server-mysql/rhel/README.md
+++ b/server-mysql/rhel/README.md
@@ -16,23 +16,25 @@ The server performs the polling and trapping of data, it calculates triggers, se
 
 # Zabbix server images
 
-These are the only official Zabbix server Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix server are:
+These are the only official Zabbix server Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix server are:
 
-    Zabbix server 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix server 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
-    Zabbix server 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2.*) (unsupported)
+    Zabbix server 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix server 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
+    Zabbix server 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix server 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
-    Zabbix server 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4.*) (unsupported)
+    Zabbix server 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
     Zabbix server 3.4.* (tags: alpine-3.4.*, ubuntu-3.4.*, centos-3.4.*) (unsupported)
     Zabbix server 4.0 (tags: alpine-4.0-latest, ubuntu-4.0-latest, centos-4.0-latest)
     Zabbix server 4.0.* (tags: alpine-4.0.*, ubuntu-4.0.*, centos-4.0.*)
-    Zabbix server 4.2 (tags: alpine-4.2-latest, ubuntu-4.2-latest, centos-4.2.*) (unsupported)
+    Zabbix server 4.2 (tags: alpine-4.2-latest, ubuntu-4.2-latest, centos-4.2-latest) (unsupported)
     Zabbix server 4.2.* (tags: alpine-4.2.*, ubuntu-4.2.*, centos-4.2.*) (unsupported)
     Zabbix server 4.4 (tags: alpine-4.4-latest, ubuntu-4.4-latest, centos-4.4-latest) (unsupported)
     Zabbix server 4.4.* (tags: alpine-4.4.*, ubuntu-4.4.*, centos-4.4.*) (unsupported)
-    Zabbix server 5.0 (tags: alpine-5.0-latest, ubuntu-5.0-latest, centos-5.0-latest, alpine-latest, ubuntu-latest, centos-latest, latest)
+    Zabbix server 5.0 (tags: alpine-5.0-latest, ubuntu-5.0-latest, centos-5.0-latest)
     Zabbix server 5.0.* (tags: alpine-5.0.*, ubuntu-5.0.*, centos-5.0.*)
-    Zabbix server 5.2 (tags: alpine-trunk, ubuntu-trunk, centos-trunk)
+    Zabbix server 5.2 (tags: alpine-5.2-latest, ubuntu-5.2-latest, centos-5.2-latest, alpine-latest, ubuntu-latest, centos-latest, latest)
+    Zabbix server 5.2.* (tags: alpine-5.2.*, ubuntu-5.2.*, centos-5.2.*)
+    Zabbix server 5.4 (tags: alpine-trunk, ubuntu-trunk, centos-trunk)
 
 Images are updated when new releases are published. The image with ``latest`` tag is based on Alpine Linux.
 
@@ -135,6 +137,9 @@ ZBX_DBTLSCERTFILE= # Available since 5.0.0
 ZBX_DBTLSKEYFILE= # Available since 5.0.0
 ZBX_DBTLSCIPHER= # Available since 5.0.0
 ZBX_DBTLSCIPHER13= # Available since 5.0.0
+ZBX_VAULTDBPATH= # Available since 5.2.0
+ZBX_VAULTURL=https://127.0.0.1:8200 # Available since 5.2.0
+VAULT_TOKEN= # Available since 5.2.0
 ZBX_LISTENIP=
 ZBX_HISTORYSTORAGEURL= # Available since 3.4.0
 ZBX_HISTORYSTORAGETYPES=uint,dbl,str,log,text # Available since 3.4.0
diff --git a/server-mysql/rhel/docker-entrypoint.sh b/server-mysql/rhel/docker-entrypoint.sh
index b00ebcbf5..85ea82c46 100755
--- a/server-mysql/rhel/docker-entrypoint.sh
+++ b/server-mysql/rhel/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -145,17 +145,17 @@ check_variables_mysql() {
 
     file_env MYSQL_ROOT_PASSWORD
 
-    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD}" == "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD,,}" == "true" ]; then
         echo "**** Impossible to use MySQL server because of unknown Zabbix user and random 'root' password"
         exit 1
     fi
 
-    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" != "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" != "true" ]; then
         echo "*** Impossible to use MySQL server because 'root' password is not defined and it is not empty"
         exit 1
     fi
 
-    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
+    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
         USE_DB_ROOT_USER=true
         DB_SERVER_ROOT_USER="root"
         DB_SERVER_ROOT_PASS=${MYSQL_ROOT_PASSWORD:-""}
@@ -165,7 +165,7 @@ check_variables_mysql() {
 
     # If root password is not specified use provided credentials
     : ${DB_SERVER_ROOT_USER:=${MYSQL_USER}}
-    [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
+    [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
     DB_SERVER_ZBX_USER=${MYSQL_USER:-"zabbix"}
     DB_SERVER_ZBX_PASS=${MYSQL_PASSWORD:-"zabbix"}
 
@@ -200,7 +200,7 @@ check_db_connect_mysql() {
     echo "* DB_SERVER_HOST: ${DB_SERVER_HOST}"
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -352,7 +352,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "StartLLDProcessors" "${ZBX_STARTLLDPROCESSORS}"
 
     : ${ZBX_JAVAGATEWAY_ENABLE:="false"}
-    if [ "${ZBX_JAVAGATEWAY_ENABLE}" == "true" ]; then
+    if [ "${ZBX_JAVAGATEWAY_ENABLE,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "JavaGateway" "${ZBX_JAVAGATEWAY:-"zabbix-java-gateway"}"
         update_config_var $ZBX_CONFIG "JavaGatewayPort" "${ZBX_JAVAGATEWAYPORT}"
         update_config_var $ZBX_CONFIG "StartJavaPollers" "${ZBX_STARTJAVAPOLLERS:-"5"}"
@@ -369,7 +369,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "VMwareTimeout" "${ZBX_VMWARETIMEOUT}"
 
     : ${ZBX_ENABLE_SNMP_TRAPS:="false"}
-    if [ "${ZBX_ENABLE_SNMP_TRAPS}" == "true" ]; then
+    if [ "${ZBX_ENABLE_SNMP_TRAPS,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "SNMPTrapperFile" "${ZABBIX_USER_HOME_DIR}/snmptraps/snmptraps.log"
         update_config_var $ZBX_CONFIG "StartSNMPTrapper" "1"
     else
diff --git a/server-mysql/ubuntu/README.md b/server-mysql/ubuntu/README.md
index d19c3cd8e..f672cd64b 100644
--- a/server-mysql/ubuntu/README.md
+++ b/server-mysql/ubuntu/README.md
@@ -16,10 +16,10 @@ The server performs the polling and trapping of data, it calculates triggers, se
 
 # Zabbix server images
 
-These are the only official Zabbix server Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix server are:
+These are the only official Zabbix server Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix server are:
 
-    Zabbix server 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix server 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix server 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix server 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix server 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix server 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix server 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/server-mysql/ubuntu/docker-entrypoint.sh b/server-mysql/ubuntu/docker-entrypoint.sh
index b8e2962f8..eaef8689d 100755
--- a/server-mysql/ubuntu/docker-entrypoint.sh
+++ b/server-mysql/ubuntu/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -145,17 +145,17 @@ check_variables_mysql() {
 
     file_env MYSQL_ROOT_PASSWORD
 
-    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD}" == "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD,,}" == "true" ]; then
         echo "**** Impossible to use MySQL server because of unknown Zabbix user and random 'root' password"
         exit 1
     fi
 
-    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" != "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" != "true" ]; then
         echo "*** Impossible to use MySQL server because 'root' password is not defined and it is not empty"
         exit 1
     fi
 
-    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
+    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
         USE_DB_ROOT_USER=true
         DB_SERVER_ROOT_USER="root"
         DB_SERVER_ROOT_PASS=${MYSQL_ROOT_PASSWORD:-""}
@@ -165,7 +165,7 @@ check_variables_mysql() {
 
     # If root password is not specified use provided credentials
     : ${DB_SERVER_ROOT_USER:=${MYSQL_USER}}
-    [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
+    [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
     DB_SERVER_ZBX_USER=${MYSQL_USER:-"zabbix"}
     DB_SERVER_ZBX_PASS=${MYSQL_PASSWORD:-"zabbix"}
 
@@ -200,7 +200,7 @@ check_db_connect_mysql() {
     echo "* DB_SERVER_HOST: ${DB_SERVER_HOST}"
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -352,7 +352,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "StartLLDProcessors" "${ZBX_STARTLLDPROCESSORS}"
 
     : ${ZBX_JAVAGATEWAY_ENABLE:="false"}
-    if [ "${ZBX_JAVAGATEWAY_ENABLE}" == "true" ]; then
+    if [ "${ZBX_JAVAGATEWAY_ENABLE,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "JavaGateway" "${ZBX_JAVAGATEWAY:-"zabbix-java-gateway"}"
         update_config_var $ZBX_CONFIG "JavaGatewayPort" "${ZBX_JAVAGATEWAYPORT}"
         update_config_var $ZBX_CONFIG "StartJavaPollers" "${ZBX_STARTJAVAPOLLERS:-"5"}"
@@ -369,7 +369,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "VMwareTimeout" "${ZBX_VMWARETIMEOUT}"
 
     : ${ZBX_ENABLE_SNMP_TRAPS:="false"}
-    if [ "${ZBX_ENABLE_SNMP_TRAPS}" == "true" ]; then
+    if [ "${ZBX_ENABLE_SNMP_TRAPS,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "SNMPTrapperFile" "${ZABBIX_USER_HOME_DIR}/snmptraps/snmptraps.log"
         update_config_var $ZBX_CONFIG "StartSNMPTrapper" "1"
     else
diff --git a/server-pgsql/alpine/README.md b/server-pgsql/alpine/README.md
index b5897b4b6..2651ce0c8 100644
--- a/server-pgsql/alpine/README.md
+++ b/server-pgsql/alpine/README.md
@@ -16,10 +16,10 @@ The server performs the polling and trapping of data, it calculates triggers, se
 
 # Zabbix server images
 
-These are the only official Zabbix server Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix server are:
+These are the only official Zabbix server Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix server are:
 
-    Zabbix server 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix server 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix server 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix server 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix server 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix server 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix server 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/server-pgsql/alpine/docker-entrypoint.sh b/server-pgsql/alpine/docker-entrypoint.sh
index 24757c93c..17e685e10 100755
--- a/server-pgsql/alpine/docker-entrypoint.sh
+++ b/server-pgsql/alpine/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -162,7 +162,7 @@ check_db_connect_postgresql() {
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
     echo "* DB_SERVER_SCHEMA: ${DB_SERVER_SCHEMA}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         echo "* DB_SERVER_ZBX_USER: ${DB_SERVER_ZBX_USER}"
         echo "* DB_SERVER_ZBX_PASS: ${DB_SERVER_ZBX_PASS}"
     fi
@@ -288,7 +288,7 @@ create_db_schema_postgresql() {
     if [ -z "${ZBX_DB_VERSION}" ]; then
         echo "** Creating '${DB_SERVER_DBNAME}' schema in PostgreSQL"
 
-        if [ "${ENABLE_TIMESCALEDB}" == "true" ]; then
+        if [ "${ENABLE_TIMESCALEDB,,}" == "true" ]; then
             psql_query "CREATE EXTENSION IF NOT EXISTS timescaledb CASCADE;"
         fi
 
@@ -312,7 +312,7 @@ create_db_schema_postgresql() {
                 --host "${DB_SERVER_HOST}" --port "${DB_SERVER_PORT}" \
                 --username "${DB_SERVER_ZBX_USER}" --dbname "${DB_SERVER_DBNAME}" 1>/dev/null || exit 1
 
-        if [ "${ENABLE_TIMESCALEDB}" == "true" ]; then
+        if [ "${ENABLE_TIMESCALEDB,,}" == "true" ]; then
             cat /usr/share/doc/zabbix-server-postgresql/timescaledb.sql | psql --quiet \
                 --host ${DB_SERVER_HOST} --port ${DB_SERVER_PORT} \
                 --username ${DB_SERVER_ZBX_USER} --dbname ${DB_SERVER_DBNAME} 1>/dev/null || exit 1
@@ -389,7 +389,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "StartLLDProcessors" "${ZBX_STARTLLDPROCESSORS}"
 
     : ${ZBX_JAVAGATEWAY_ENABLE:="false"}
-    if [ "${ZBX_JAVAGATEWAY_ENABLE}" == "true" ]; then
+    if [ "${ZBX_JAVAGATEWAY_ENABLE,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "JavaGateway" "${ZBX_JAVAGATEWAY:-"zabbix-java-gateway"}"
         update_config_var $ZBX_CONFIG "JavaGatewayPort" "${ZBX_JAVAGATEWAYPORT}"
         update_config_var $ZBX_CONFIG "StartJavaPollers" "${ZBX_STARTJAVAPOLLERS:-"5"}"
@@ -406,7 +406,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "VMwareTimeout" "${ZBX_VMWARETIMEOUT}"
 
     : ${ZBX_ENABLE_SNMP_TRAPS:="false"}
-    if [ "${ZBX_ENABLE_SNMP_TRAPS}" == "true" ]; then
+    if [ "${ZBX_ENABLE_SNMP_TRAPS,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "SNMPTrapperFile" "${ZABBIX_USER_HOME_DIR}/snmptraps/snmptraps.log"
         update_config_var $ZBX_CONFIG "StartSNMPTrapper" "1"
     else
diff --git a/server-pgsql/centos/README.md b/server-pgsql/centos/README.md
index b5897b4b6..2651ce0c8 100644
--- a/server-pgsql/centos/README.md
+++ b/server-pgsql/centos/README.md
@@ -16,10 +16,10 @@ The server performs the polling and trapping of data, it calculates triggers, se
 
 # Zabbix server images
 
-These are the only official Zabbix server Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix server are:
+These are the only official Zabbix server Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix server are:
 
-    Zabbix server 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix server 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix server 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix server 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix server 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix server 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix server 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/server-pgsql/centos/docker-entrypoint.sh b/server-pgsql/centos/docker-entrypoint.sh
index 24757c93c..17e685e10 100755
--- a/server-pgsql/centos/docker-entrypoint.sh
+++ b/server-pgsql/centos/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -162,7 +162,7 @@ check_db_connect_postgresql() {
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
     echo "* DB_SERVER_SCHEMA: ${DB_SERVER_SCHEMA}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         echo "* DB_SERVER_ZBX_USER: ${DB_SERVER_ZBX_USER}"
         echo "* DB_SERVER_ZBX_PASS: ${DB_SERVER_ZBX_PASS}"
     fi
@@ -288,7 +288,7 @@ create_db_schema_postgresql() {
     if [ -z "${ZBX_DB_VERSION}" ]; then
         echo "** Creating '${DB_SERVER_DBNAME}' schema in PostgreSQL"
 
-        if [ "${ENABLE_TIMESCALEDB}" == "true" ]; then
+        if [ "${ENABLE_TIMESCALEDB,,}" == "true" ]; then
             psql_query "CREATE EXTENSION IF NOT EXISTS timescaledb CASCADE;"
         fi
 
@@ -312,7 +312,7 @@ create_db_schema_postgresql() {
                 --host "${DB_SERVER_HOST}" --port "${DB_SERVER_PORT}" \
                 --username "${DB_SERVER_ZBX_USER}" --dbname "${DB_SERVER_DBNAME}" 1>/dev/null || exit 1
 
-        if [ "${ENABLE_TIMESCALEDB}" == "true" ]; then
+        if [ "${ENABLE_TIMESCALEDB,,}" == "true" ]; then
             cat /usr/share/doc/zabbix-server-postgresql/timescaledb.sql | psql --quiet \
                 --host ${DB_SERVER_HOST} --port ${DB_SERVER_PORT} \
                 --username ${DB_SERVER_ZBX_USER} --dbname ${DB_SERVER_DBNAME} 1>/dev/null || exit 1
@@ -389,7 +389,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "StartLLDProcessors" "${ZBX_STARTLLDPROCESSORS}"
 
     : ${ZBX_JAVAGATEWAY_ENABLE:="false"}
-    if [ "${ZBX_JAVAGATEWAY_ENABLE}" == "true" ]; then
+    if [ "${ZBX_JAVAGATEWAY_ENABLE,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "JavaGateway" "${ZBX_JAVAGATEWAY:-"zabbix-java-gateway"}"
         update_config_var $ZBX_CONFIG "JavaGatewayPort" "${ZBX_JAVAGATEWAYPORT}"
         update_config_var $ZBX_CONFIG "StartJavaPollers" "${ZBX_STARTJAVAPOLLERS:-"5"}"
@@ -406,7 +406,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "VMwareTimeout" "${ZBX_VMWARETIMEOUT}"
 
     : ${ZBX_ENABLE_SNMP_TRAPS:="false"}
-    if [ "${ZBX_ENABLE_SNMP_TRAPS}" == "true" ]; then
+    if [ "${ZBX_ENABLE_SNMP_TRAPS,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "SNMPTrapperFile" "${ZABBIX_USER_HOME_DIR}/snmptraps/snmptraps.log"
         update_config_var $ZBX_CONFIG "StartSNMPTrapper" "1"
     else
diff --git a/server-pgsql/ubuntu/README.md b/server-pgsql/ubuntu/README.md
index b5897b4b6..2651ce0c8 100644
--- a/server-pgsql/ubuntu/README.md
+++ b/server-pgsql/ubuntu/README.md
@@ -16,10 +16,10 @@ The server performs the polling and trapping of data, it calculates triggers, se
 
 # Zabbix server images
 
-These are the only official Zabbix server Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix server are:
+These are the only official Zabbix server Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix server are:
 
-    Zabbix server 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix server 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix server 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix server 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix server 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix server 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix server 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/server-pgsql/ubuntu/docker-entrypoint.sh b/server-pgsql/ubuntu/docker-entrypoint.sh
index 480141f6e..ca12dbb0d 100755
--- a/server-pgsql/ubuntu/docker-entrypoint.sh
+++ b/server-pgsql/ubuntu/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -162,7 +162,7 @@ check_db_connect_postgresql() {
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
     echo "* DB_SERVER_SCHEMA: ${DB_SERVER_SCHEMA}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         echo "* DB_SERVER_ZBX_USER: ${DB_SERVER_ZBX_USER}"
         echo "* DB_SERVER_ZBX_PASS: ${DB_SERVER_ZBX_PASS}"
     fi
@@ -288,7 +288,7 @@ create_db_schema_postgresql() {
     if [ -z "${ZBX_DB_VERSION}" ]; then
         echo "** Creating '${DB_SERVER_DBNAME}' schema in PostgreSQL"
 
-        if [ "${ENABLE_TIMESCALEDB}" == "true" ]; then
+        if [ "${ENABLE_TIMESCALEDB,,}" == "true" ]; then
             psql_query "CREATE EXTENSION IF NOT EXISTS timescaledb CASCADE;"
         fi
 
@@ -312,7 +312,7 @@ create_db_schema_postgresql() {
                 --host "${DB_SERVER_HOST}" --port "${DB_SERVER_PORT}" \
                 --username "${DB_SERVER_ZBX_USER}" --dbname "${DB_SERVER_DBNAME}" 1>/dev/null || exit 1
 
-        if [ "${ENABLE_TIMESCALEDB}" == "true" ]; then
+        if [ "${ENABLE_TIMESCALEDB,,}" == "true" ]; then
             cat /usr/share/doc/zabbix-server-postgresql/timescaledb.sql | psql --quiet \
                 --host ${DB_SERVER_HOST} --port ${DB_SERVER_PORT} \
                 --username ${DB_SERVER_ZBX_USER} --dbname ${DB_SERVER_DBNAME} 1>/dev/null || exit 1
@@ -389,7 +389,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "StartLLDProcessors" "${ZBX_STARTLLDPROCESSORS}"
 
     : ${ZBX_JAVAGATEWAY_ENABLE:="false"}
-    if [ "${ZBX_JAVAGATEWAY_ENABLE}" == "true" ]; then
+    if [ "${ZBX_JAVAGATEWAY_ENABLE,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "JavaGateway" "${ZBX_JAVAGATEWAY:-"zabbix-java-gateway"}"
         update_config_var $ZBX_CONFIG "JavaGatewayPort" "${ZBX_JAVAGATEWAYPORT}"
         update_config_var $ZBX_CONFIG "StartJavaPollers" "${ZBX_STARTJAVAPOLLERS:-"5"}"
@@ -406,7 +406,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "VMwareTimeout" "${ZBX_VMWARETIMEOUT}"
 
     : ${ZBX_ENABLE_SNMP_TRAPS:="false"}
-    if [ "${ZBX_ENABLE_SNMP_TRAPS}" == "true" ]; then
+    if [ "${ZBX_ENABLE_SNMP_TRAPS,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "SNMPTrapperFile" "${ZABBIX_USER_HOME_DIR}/snmptraps/snmptraps.log"
         update_config_var $ZBX_CONFIG "StartSNMPTrapper" "1"
     else
diff --git a/snmptraps/alpine/README.md b/snmptraps/alpine/README.md
index dd0f8ee31..471da9d1d 100644
--- a/snmptraps/alpine/README.md
+++ b/snmptraps/alpine/README.md
@@ -14,10 +14,10 @@ The image is used to receive SNMP traps, store them to a log file and provide ac
 
 # Zabbix snmptraps images
 
-These are the only official Zabbix snmptraps Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix snmptraps are:
+These are the only official Zabbix snmptraps Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix snmptraps are:
 
-    Zabbix snmptraps 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix snmptraps 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix snmptraps 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix snmptraps 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix snmptraps 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix snmptraps 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix snmptraps 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
@@ -42,7 +42,7 @@ Images are updated when new releases are published.
 
 Start a Zabbix snmptraps container as follows:
 
-    docker run --name some-zabbix-snmptraps -d zabbix/zabbix-snmptraps:tag
+    docker run --name some-zabbix-snmptraps -p 162:1162/udp -d zabbix/zabbix-snmptraps:tag
 
 Where `some-zabbix-snmptraps` is the name you want to assign to your container and `tag` is the tag specifying the version you want. See the list above for relevant tags, or look at the [full list of tags](https://hub.docker.com/r/zabbix/zabbix-snmptraps/tags/).
 
diff --git a/snmptraps/centos/README.md b/snmptraps/centos/README.md
index dd0f8ee31..471da9d1d 100644
--- a/snmptraps/centos/README.md
+++ b/snmptraps/centos/README.md
@@ -14,10 +14,10 @@ The image is used to receive SNMP traps, store them to a log file and provide ac
 
 # Zabbix snmptraps images
 
-These are the only official Zabbix snmptraps Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix snmptraps are:
+These are the only official Zabbix snmptraps Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix snmptraps are:
 
-    Zabbix snmptraps 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix snmptraps 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix snmptraps 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix snmptraps 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix snmptraps 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix snmptraps 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix snmptraps 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
@@ -42,7 +42,7 @@ Images are updated when new releases are published.
 
 Start a Zabbix snmptraps container as follows:
 
-    docker run --name some-zabbix-snmptraps -d zabbix/zabbix-snmptraps:tag
+    docker run --name some-zabbix-snmptraps -p 162:1162/udp -d zabbix/zabbix-snmptraps:tag
 
 Where `some-zabbix-snmptraps` is the name you want to assign to your container and `tag` is the tag specifying the version you want. See the list above for relevant tags, or look at the [full list of tags](https://hub.docker.com/r/zabbix/zabbix-snmptraps/tags/).
 
diff --git a/snmptraps/ubuntu/README.md b/snmptraps/ubuntu/README.md
index dd0f8ee31..471da9d1d 100644
--- a/snmptraps/ubuntu/README.md
+++ b/snmptraps/ubuntu/README.md
@@ -14,10 +14,10 @@ The image is used to receive SNMP traps, store them to a log file and provide ac
 
 # Zabbix snmptraps images
 
-These are the only official Zabbix snmptraps Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix snmptraps are:
+These are the only official Zabbix snmptraps Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix snmptraps are:
 
-    Zabbix snmptraps 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix snmptraps 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix snmptraps 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix snmptraps 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix snmptraps 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix snmptraps 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix snmptraps 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
@@ -42,7 +42,7 @@ Images are updated when new releases are published.
 
 Start a Zabbix snmptraps container as follows:
 
-    docker run --name some-zabbix-snmptraps -d zabbix/zabbix-snmptraps:tag
+    docker run --name some-zabbix-snmptraps -p 162:1162/udp -d zabbix/zabbix-snmptraps:tag
 
 Where `some-zabbix-snmptraps` is the name you want to assign to your container and `tag` is the tag specifying the version you want. See the list above for relevant tags, or look at the [full list of tags](https://hub.docker.com/r/zabbix/zabbix-snmptraps/tags/).
 
diff --git a/web-apache-mysql/alpine/README.md b/web-apache-mysql/alpine/README.md
index 8dae45c23..e9d5c110f 100644
--- a/web-apache-mysql/alpine/README.md
+++ b/web-apache-mysql/alpine/README.md
@@ -14,10 +14,10 @@ Zabbix web interface is a part of Zabbix software. It is used to manage resource
 
 # Zabbix web interface images
 
-These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix web interface are:
+These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix web interface are:
 
-    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix web interface 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix web interface 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix web interface 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/web-apache-mysql/alpine/docker-entrypoint.sh b/web-apache-mysql/alpine/docker-entrypoint.sh
index 3c287a3c0..5051029e5 100755
--- a/web-apache-mysql/alpine/docker-entrypoint.sh
+++ b/web-apache-mysql/alpine/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -66,17 +66,17 @@ check_variables() {
     file_env MYSQL_USER
     file_env MYSQL_PASSWORD
 
-    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD}" == "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD,,}" == "true" ]; then
         echo "**** Impossible to use MySQL server because of unknown Zabbix user and random 'root' password"
         exit 1
     fi
 
-    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" != "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" != "true" ]; then
         echo "*** Impossible to use MySQL server because 'root' password is not defined and it is not empty"
         exit 1
     fi
 
-    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
+    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
         USE_DB_ROOT_USER=true
         DB_SERVER_ROOT_USER="root"
         DB_SERVER_ROOT_PASS=${MYSQL_ROOT_PASSWORD:-""}
@@ -86,7 +86,7 @@ check_variables() {
 
     # If root password is not specified use provided credentials
     : ${DB_SERVER_ROOT_USER:=${MYSQL_USER}}
-    [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
+    [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
     DB_SERVER_ZBX_USER=${MYSQL_USER:-"zabbix"}
     DB_SERVER_ZBX_PASS=${MYSQL_PASSWORD:-"zabbix"}
 
@@ -96,7 +96,7 @@ check_variables() {
 db_tls_params() {
     local result=""
 
-    if [ "${ZBX_DB_ENCRYPTION}" == "true" ]; then
+    if [ "${ZBX_DB_ENCRYPTION,,}" == "true" ]; then
         result="--ssl"
 
         if [ -n "${ZBX_DB_CA_FILE}" ]; then
@@ -120,7 +120,7 @@ check_db_connect() {
     echo "* DB_SERVER_HOST: ${DB_SERVER_HOST}"
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -170,7 +170,8 @@ prepare_web_server() {
 prepare_zbx_web_config() {
     echo "** Preparing Zabbix frontend configuration file"
 
-    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS,,}
     export ZBX_GUI_ACCESS_IP_RANGE=${ZBX_GUI_ACCESS_IP_RANGE:-"['127.0.0.1']"}
     export ZBX_GUI_WARNING_MSG=${ZBX_GUI_WARNING_MSG:-"Zabbix is under maintenance."}
 
@@ -192,13 +193,16 @@ prepare_zbx_web_config() {
     export ZBX_SERVER_PORT=${ZBX_SERVER_PORT:-"10051"}
     export ZBX_SERVER_NAME=${ZBX_SERVER_NAME}
 
-    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION,,}
     export ZBX_DB_KEY_FILE=${ZBX_DB_KEY_FILE}
     export ZBX_DB_CERT_FILE=${ZBX_DB_CERT_FILE}
     export ZBX_DB_CA_FILE=${ZBX_DB_CA_FILE}
-    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST-"false"}
+    ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST:-"false"}
+    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST,,}
 
-    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754,,}
 
     export ZBX_HISTORYSTORAGEURL=${ZBX_HISTORYSTORAGEURL}
     export ZBX_HISTORYSTORAGETYPES=${ZBX_HISTORYSTORAGETYPES:-"[]"}
@@ -211,7 +215,9 @@ prepare_zbx_web_config() {
         rm -f "/tmp/defines.inc.php_tmp"
     fi
 
-    if [ "${ENABLE_WEB_ACCESS_LOG:-"true"}" == "false" ]; then
+    ENABLE_WEB_ACCESS_LOG=${ENABLE_WEB_ACCESS_LOG:-"true"}
+
+    if [ "${ENABLE_WEB_ACCESS_LOG,,}" == "false" ]; then
         sed -ri \
             -e 's!^(\s*CustomLog)\s+\S+!\1 /dev/null!g' \
             "/etc/apache2/httpd.conf"
diff --git a/web-apache-mysql/centos/README.md b/web-apache-mysql/centos/README.md
index 8dae45c23..e9d5c110f 100644
--- a/web-apache-mysql/centos/README.md
+++ b/web-apache-mysql/centos/README.md
@@ -14,10 +14,10 @@ Zabbix web interface is a part of Zabbix software. It is used to manage resource
 
 # Zabbix web interface images
 
-These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix web interface are:
+These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix web interface are:
 
-    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix web interface 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix web interface 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix web interface 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/web-apache-mysql/centos/docker-entrypoint.sh b/web-apache-mysql/centos/docker-entrypoint.sh
index 1cea78c64..9f383f509 100755
--- a/web-apache-mysql/centos/docker-entrypoint.sh
+++ b/web-apache-mysql/centos/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -66,17 +66,17 @@ check_variables() {
     file_env MYSQL_USER
     file_env MYSQL_PASSWORD
 
-    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD}" == "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD,,}" == "true" ]; then
         echo "**** Impossible to use MySQL server because of unknown Zabbix user and random 'root' password"
         exit 1
     fi
 
-    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" != "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" != "true" ]; then
         echo "*** Impossible to use MySQL server because 'root' password is not defined and it is not empty"
         exit 1
     fi
 
-    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
+    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
         USE_DB_ROOT_USER=true
         DB_SERVER_ROOT_USER="root"
         DB_SERVER_ROOT_PASS=${MYSQL_ROOT_PASSWORD:-""}
@@ -86,7 +86,7 @@ check_variables() {
 
     # If root password is not specified use provided credentials
     : ${DB_SERVER_ROOT_USER:=${MYSQL_USER}}
-    [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
+    [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
     DB_SERVER_ZBX_USER=${MYSQL_USER:-"zabbix"}
     DB_SERVER_ZBX_PASS=${MYSQL_PASSWORD:-"zabbix"}
 
@@ -96,7 +96,7 @@ check_variables() {
 db_tls_params() {
     local result=""
 
-    if [ "${ZBX_DB_ENCRYPTION}" == "true" ]; then
+    if [ "${ZBX_DB_ENCRYPTION,,}" == "true" ]; then
         result="--ssl-mode=required"
 
         if [ -n "${ZBX_DB_CA_FILE}" ]; then
@@ -120,7 +120,7 @@ check_db_connect() {
     echo "* DB_SERVER_HOST: ${DB_SERVER_HOST}"
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -179,7 +179,8 @@ prepare_zbx_web_config() {
         echo "listen.group = nginx" >> "$PHP_CONFIG_FILE"
     fi
 
-    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS,,}
     export ZBX_GUI_ACCESS_IP_RANGE=${ZBX_GUI_ACCESS_IP_RANGE:-"['127.0.0.1']"}
     export ZBX_GUI_WARNING_MSG=${ZBX_GUI_WARNING_MSG:-"Zabbix is under maintenance."}
 
@@ -201,13 +202,16 @@ prepare_zbx_web_config() {
     export ZBX_SERVER_PORT=${ZBX_SERVER_PORT:-"10051"}
     export ZBX_SERVER_NAME=${ZBX_SERVER_NAME}
 
-    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION,,}
     export ZBX_DB_KEY_FILE=${ZBX_DB_KEY_FILE}
     export ZBX_DB_CERT_FILE=${ZBX_DB_CERT_FILE}
     export ZBX_DB_CA_FILE=${ZBX_DB_CA_FILE}
-    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST-"false"}
+    ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST:-"false"}
+    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST,,}
 
-    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754,,}
 
     export ZBX_HISTORYSTORAGEURL=${ZBX_HISTORYSTORAGEURL}
     export ZBX_HISTORYSTORAGETYPES=${ZBX_HISTORYSTORAGETYPES:-"[]"}
@@ -220,7 +224,9 @@ prepare_zbx_web_config() {
         rm -f "/tmp/defines.inc.php_tmp"
     fi
 
-    if [ "${ENABLE_WEB_ACCESS_LOG:-"true"}" == "false" ]; then
+    ENABLE_WEB_ACCESS_LOG=${ENABLE_WEB_ACCESS_LOG:-"true"}
+
+    if [ "${ENABLE_WEB_ACCESS_LOG,,}" == "false" ]; then
         sed -ri \
             -e 's!^(\s*CustomLog)\s+\S+!\1 /dev/null!g' \
             "/etc/httpd/conf/httpd.conf"
diff --git a/web-apache-mysql/ubuntu/README.md b/web-apache-mysql/ubuntu/README.md
index 8dae45c23..e9d5c110f 100644
--- a/web-apache-mysql/ubuntu/README.md
+++ b/web-apache-mysql/ubuntu/README.md
@@ -14,10 +14,10 @@ Zabbix web interface is a part of Zabbix software. It is used to manage resource
 
 # Zabbix web interface images
 
-These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix web interface are:
+These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix web interface are:
 
-    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix web interface 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix web interface 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix web interface 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/web-apache-mysql/ubuntu/docker-entrypoint.sh b/web-apache-mysql/ubuntu/docker-entrypoint.sh
index 95cc9e155..fb4742ed5 100755
--- a/web-apache-mysql/ubuntu/docker-entrypoint.sh
+++ b/web-apache-mysql/ubuntu/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -66,17 +66,17 @@ check_variables() {
     file_env MYSQL_USER
     file_env MYSQL_PASSWORD
 
-    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD}" == "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD,,}" == "true" ]; then
         echo "**** Impossible to use MySQL server because of unknown Zabbix user and random 'root' password"
         exit 1
     fi
 
-    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" != "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" != "true" ]; then
         echo "*** Impossible to use MySQL server because 'root' password is not defined and it is not empty"
         exit 1
     fi
 
-    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
+    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
         USE_DB_ROOT_USER=true
         DB_SERVER_ROOT_USER="root"
         DB_SERVER_ROOT_PASS=${MYSQL_ROOT_PASSWORD:-""}
@@ -86,7 +86,7 @@ check_variables() {
 
     # If root password is not specified use provided credentials
     : ${DB_SERVER_ROOT_USER:=${MYSQL_USER}}
-    [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
+    [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
     DB_SERVER_ZBX_USER=${MYSQL_USER:-"zabbix"}
     DB_SERVER_ZBX_PASS=${MYSQL_PASSWORD:-"zabbix"}
 
@@ -96,7 +96,7 @@ check_variables() {
 db_tls_params() {
     local result=""
 
-    if [ "${ZBX_DB_ENCRYPTION}" == "true" ]; then
+    if [ "${ZBX_DB_ENCRYPTION,,}" == "true" ]; then
         result="--ssl-mode=required"
 
         if [ -n "${ZBX_DB_CA_FILE}" ]; then
@@ -120,7 +120,7 @@ check_db_connect() {
     echo "* DB_SERVER_HOST: ${DB_SERVER_HOST}"
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -170,7 +170,8 @@ prepare_web_server() {
 prepare_zbx_web_config() {
     echo "** Preparing Zabbix frontend configuration file"
 
-    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS,,}
     export ZBX_GUI_ACCESS_IP_RANGE=${ZBX_GUI_ACCESS_IP_RANGE:-"['127.0.0.1']"}
     export ZBX_GUI_WARNING_MSG=${ZBX_GUI_WARNING_MSG:-"Zabbix is under maintenance."}
 
@@ -192,13 +193,16 @@ prepare_zbx_web_config() {
     export ZBX_SERVER_PORT=${ZBX_SERVER_PORT:-"10051"}
     export ZBX_SERVER_NAME=${ZBX_SERVER_NAME}
 
-    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION,,}
     export ZBX_DB_KEY_FILE=${ZBX_DB_KEY_FILE}
     export ZBX_DB_CERT_FILE=${ZBX_DB_CERT_FILE}
     export ZBX_DB_CA_FILE=${ZBX_DB_CA_FILE}
-    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST-"false"}
+    ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST:-"false"}
+    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST,,}
 
-    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754,,}
 
     export ZBX_HISTORYSTORAGEURL=${ZBX_HISTORYSTORAGEURL}
     export ZBX_HISTORYSTORAGETYPES=${ZBX_HISTORYSTORAGETYPES:-"[]"}
@@ -211,7 +215,9 @@ prepare_zbx_web_config() {
         rm -f "/tmp/defines.inc.php_tmp"
     fi
 
-    if [ "${ENABLE_WEB_ACCESS_LOG:-"true"}" == "false" ]; then
+    ENABLE_WEB_ACCESS_LOG=${ENABLE_WEB_ACCESS_LOG:-"true"}
+
+    if [ "${ENABLE_WEB_ACCESS_LOG,,}" == "false" ]; then
         sed -ri \
             -e 's!^(\s*CustomLog)\s+\S+!\1 /dev/null!g' \
             "/etc/apache2/apache2.conf"
diff --git a/web-apache-pgsql/alpine/README.md b/web-apache-pgsql/alpine/README.md
index b8e5d55be..2dc5f1a8a 100644
--- a/web-apache-pgsql/alpine/README.md
+++ b/web-apache-pgsql/alpine/README.md
@@ -14,10 +14,10 @@ Zabbix web interface is a part of Zabbix software. It is used to manage resource
 
 # Zabbix web interface images
 
-These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix web interface are:
+These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix web interface are:
 
-    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix web interface 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix web interface 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix web interface 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/web-apache-pgsql/alpine/docker-entrypoint.sh b/web-apache-pgsql/alpine/docker-entrypoint.sh
index 77663ad73..7cee84593 100755
--- a/web-apache-pgsql/alpine/docker-entrypoint.sh
+++ b/web-apache-pgsql/alpine/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -83,7 +83,7 @@ check_db_connect() {
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
     echo "* DB_SERVER_SCHEMA: ${DB_SERVER_SCHEMA}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -154,7 +154,8 @@ prepare_web_server() {
 prepare_zbx_web_config() {
     echo "** Preparing Zabbix frontend configuration file"
 
-    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS,,}
     export ZBX_GUI_ACCESS_IP_RANGE=${ZBX_GUI_ACCESS_IP_RANGE:-"['127.0.0.1']"}
     export ZBX_GUI_WARNING_MSG=${ZBX_GUI_WARNING_MSG:-"Zabbix is under maintenance."}
 
@@ -176,13 +177,16 @@ prepare_zbx_web_config() {
     export ZBX_SERVER_PORT=${ZBX_SERVER_PORT:-"10051"}
     export ZBX_SERVER_NAME=${ZBX_SERVER_NAME}
 
-    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION,,}
     export ZBX_DB_KEY_FILE=${ZBX_DB_KEY_FILE}
     export ZBX_DB_CERT_FILE=${ZBX_DB_CERT_FILE}
     export ZBX_DB_CA_FILE=${ZBX_DB_CA_FILE}
-    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST-"false"}
+    ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST:-"false"}
+    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST,,}
 
-    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754,,}
 
     export ZBX_HISTORYSTORAGEURL=${ZBX_HISTORYSTORAGEURL}
     export ZBX_HISTORYSTORAGETYPES=${ZBX_HISTORYSTORAGETYPES:-"[]"}
@@ -195,7 +199,9 @@ prepare_zbx_web_config() {
         rm -f "/tmp/defines.inc.php_tmp"
     fi
 
-    if [ "${ENABLE_WEB_ACCESS_LOG:-"true"}" == "false" ]; then
+    ENABLE_WEB_ACCESS_LOG=${ENABLE_WEB_ACCESS_LOG:-"true"}
+
+    if [ "${ENABLE_WEB_ACCESS_LOG,,}" == "false" ]; then
         sed -ri \
             -e 's!^(\s*CustomLog)\s+\S+!\1 /dev/null!g' \
             "/etc/apache2/httpd.conf"
diff --git a/web-apache-pgsql/centos/README.md b/web-apache-pgsql/centos/README.md
index b8e5d55be..2dc5f1a8a 100644
--- a/web-apache-pgsql/centos/README.md
+++ b/web-apache-pgsql/centos/README.md
@@ -14,10 +14,10 @@ Zabbix web interface is a part of Zabbix software. It is used to manage resource
 
 # Zabbix web interface images
 
-These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix web interface are:
+These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix web interface are:
 
-    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix web interface 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix web interface 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix web interface 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/web-apache-pgsql/centos/docker-entrypoint.sh b/web-apache-pgsql/centos/docker-entrypoint.sh
index 9c4cf6b6c..be20aea2e 100755
--- a/web-apache-pgsql/centos/docker-entrypoint.sh
+++ b/web-apache-pgsql/centos/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -86,7 +86,7 @@ check_db_connect() {
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
     echo "* DB_SERVER_SCHEMA: ${DB_SERVER_SCHEMA}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -166,7 +166,8 @@ prepare_zbx_web_config() {
         echo "listen.group = nginx" >> "$PHP_CONFIG_FILE"
     fi
 
-    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS,,}
     export ZBX_GUI_ACCESS_IP_RANGE=${ZBX_GUI_ACCESS_IP_RANGE:-"['127.0.0.1']"}
     export ZBX_GUI_WARNING_MSG=${ZBX_GUI_WARNING_MSG:-"Zabbix is under maintenance."}
 
@@ -188,13 +189,16 @@ prepare_zbx_web_config() {
     export ZBX_SERVER_PORT=${ZBX_SERVER_PORT:-"10051"}
     export ZBX_SERVER_NAME=${ZBX_SERVER_NAME}
 
-    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION,,}
     export ZBX_DB_KEY_FILE=${ZBX_DB_KEY_FILE}
     export ZBX_DB_CERT_FILE=${ZBX_DB_CERT_FILE}
     export ZBX_DB_CA_FILE=${ZBX_DB_CA_FILE}
-    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST-"false"}
+    ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST:-"false"}
+    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST,,}
 
-    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754,,}
 
     export ZBX_HISTORYSTORAGEURL=${ZBX_HISTORYSTORAGEURL}
     export ZBX_HISTORYSTORAGETYPES=${ZBX_HISTORYSTORAGETYPES:-"[]"}
@@ -207,7 +211,9 @@ prepare_zbx_web_config() {
         rm -f "/tmp/defines.inc.php_tmp"
     fi
 
-    if [ "${ENABLE_WEB_ACCESS_LOG:-"true"}" == "false" ]; then
+    ENABLE_WEB_ACCESS_LOG=${ENABLE_WEB_ACCESS_LOG:-"true"}
+
+    if [ "${ENABLE_WEB_ACCESS_LOG,,}" == "false" ]; then
         sed -ri \
             -e 's!^(\s*CustomLog)\s+\S+!\1 /dev/null!g' \
             "/etc/httpd/conf/httpd.conf"
diff --git a/web-apache-pgsql/ubuntu/README.md b/web-apache-pgsql/ubuntu/README.md
index b8e5d55be..2dc5f1a8a 100644
--- a/web-apache-pgsql/ubuntu/README.md
+++ b/web-apache-pgsql/ubuntu/README.md
@@ -14,10 +14,10 @@ Zabbix web interface is a part of Zabbix software. It is used to manage resource
 
 # Zabbix web interface images
 
-These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix web interface are:
+These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix web interface are:
 
-    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix web interface 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix web interface 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix web interface 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/web-apache-pgsql/ubuntu/docker-entrypoint.sh b/web-apache-pgsql/ubuntu/docker-entrypoint.sh
index 2de0a4446..23db5c5ac 100755
--- a/web-apache-pgsql/ubuntu/docker-entrypoint.sh
+++ b/web-apache-pgsql/ubuntu/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -86,7 +86,7 @@ check_db_connect() {
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
     echo "* DB_SERVER_SCHEMA: ${DB_SERVER_SCHEMA}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -161,7 +161,8 @@ clear_deploy() {
 prepare_zbx_web_config() {
     echo "** Preparing Zabbix frontend configuration file"
 
-    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS,,}
     export ZBX_GUI_ACCESS_IP_RANGE=${ZBX_GUI_ACCESS_IP_RANGE:-"['127.0.0.1']"}
     export ZBX_GUI_WARNING_MSG=${ZBX_GUI_WARNING_MSG:-"Zabbix is under maintenance."}
 
@@ -183,13 +184,16 @@ prepare_zbx_web_config() {
     export ZBX_SERVER_PORT=${ZBX_SERVER_PORT:-"10051"}
     export ZBX_SERVER_NAME=${ZBX_SERVER_NAME}
 
-    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION,,c}
     export ZBX_DB_KEY_FILE=${ZBX_DB_KEY_FILE}
     export ZBX_DB_CERT_FILE=${ZBX_DB_CERT_FILE}
     export ZBX_DB_CA_FILE=${ZBX_DB_CA_FILE}
-    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST-"false"}
+    ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST:-"false"}
+    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST,,}
 
-    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754,,}
 
     export ZBX_HISTORYSTORAGEURL=${ZBX_HISTORYSTORAGEURL}
     export ZBX_HISTORYSTORAGETYPES=${ZBX_HISTORYSTORAGETYPES:-"[]"}
@@ -202,7 +206,9 @@ prepare_zbx_web_config() {
         rm -f "/tmp/defines.inc.php_tmp"
     fi
 
-    if [ "${ENABLE_WEB_ACCESS_LOG:-"true"}" == "false" ]; then
+    ENABLE_WEB_ACCESS_LOG=${ENABLE_WEB_ACCESS_LOG:-"true"}
+
+    if [ "${ENABLE_WEB_ACCESS_LOG,,}" == "false" ]; then
         sed -ri \
             -e 's!^(\s*CustomLog)\s+\S+!\1 /dev/null!g' \
             "/etc/apache2/apache2.conf"
diff --git a/web-nginx-mysql/alpine/README.md b/web-nginx-mysql/alpine/README.md
index 76571af93..89d375a05 100644
--- a/web-nginx-mysql/alpine/README.md
+++ b/web-nginx-mysql/alpine/README.md
@@ -14,10 +14,10 @@ Zabbix web interface is a part of Zabbix software. It is used to manage resource
 
 # Zabbix web interface images
 
-These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix web interface are:
+These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix web interface are:
 
-    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix web interface 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix web interface 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix web interface 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/web-nginx-mysql/alpine/docker-entrypoint.sh b/web-nginx-mysql/alpine/docker-entrypoint.sh
index 7465a5c27..40aeef4a0 100755
--- a/web-nginx-mysql/alpine/docker-entrypoint.sh
+++ b/web-nginx-mysql/alpine/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -66,17 +66,17 @@ check_variables() {
     file_env MYSQL_USER
     file_env MYSQL_PASSWORD
 
-    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD}" == "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD,,}" == "true" ]; then
         echo "**** Impossible to use MySQL server because of unknown Zabbix user and random 'root' password"
         exit 1
     fi
 
-    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" != "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" != "true" ]; then
         echo "*** Impossible to use MySQL server because 'root' password is not defined and it is not empty"
         exit 1
     fi
 
-    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
+    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
         USE_DB_ROOT_USER=true
         DB_SERVER_ROOT_USER="root"
         DB_SERVER_ROOT_PASS=${MYSQL_ROOT_PASSWORD:-""}
@@ -86,7 +86,7 @@ check_variables() {
 
     # If root password is not specified use provided credentials
     : ${DB_SERVER_ROOT_USER:=${MYSQL_USER}}
-    [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
+    [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
     DB_SERVER_ZBX_USER=${MYSQL_USER:-"zabbix"}
     DB_SERVER_ZBX_PASS=${MYSQL_PASSWORD:-"zabbix"}
 
@@ -96,7 +96,7 @@ check_variables() {
 db_tls_params() {
     local result=""
 
-    if [ "${ZBX_DB_ENCRYPTION}" == "true" ]; then
+    if [ "${ZBX_DB_ENCRYPTION,,}" == "true" ]; then
         result="--ssl"
 
         if [ -n "${ZBX_DB_CA_FILE}" ]; then
@@ -120,7 +120,7 @@ check_db_connect() {
     echo "* DB_SERVER_HOST: ${DB_SERVER_HOST}"
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -180,7 +180,8 @@ prepare_zbx_web_config() {
         echo "listen.group = nginx" >> "$PHP_CONFIG_FILE"
     fi
 
-    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS,,}
     export ZBX_GUI_ACCESS_IP_RANGE=${ZBX_GUI_ACCESS_IP_RANGE:-"['127.0.0.1']"}
     export ZBX_GUI_WARNING_MSG=${ZBX_GUI_WARNING_MSG:-"Zabbix is under maintenance."}
 
@@ -202,13 +203,16 @@ prepare_zbx_web_config() {
     export ZBX_SERVER_PORT=${ZBX_SERVER_PORT:-"10051"}
     export ZBX_SERVER_NAME=${ZBX_SERVER_NAME}
 
-    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION,,}
     export ZBX_DB_KEY_FILE=${ZBX_DB_KEY_FILE}
     export ZBX_DB_CERT_FILE=${ZBX_DB_CERT_FILE}
     export ZBX_DB_CA_FILE=${ZBX_DB_CA_FILE}
-    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST-"false"}
+    ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST:-"false"}
+    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST,,}
 
-    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754,,}
 
     export ZBX_HISTORYSTORAGEURL=${ZBX_HISTORYSTORAGEURL}
     export ZBX_HISTORYSTORAGETYPES=${ZBX_HISTORYSTORAGETYPES:-"[]"}
@@ -232,7 +236,9 @@ prepare_zbx_web_config() {
         "$ZABBIX_ETC_DIR/nginx_ssl.conf"
     fi
 
-    if [ "${ENABLE_WEB_ACCESS_LOG:-"true"}" == "false" ]; then
+    ENABLE_WEB_ACCESS_LOG=${ENABLE_WEB_ACCESS_LOG:-"true"}
+
+    if [ "${ENABLE_WEB_ACCESS_LOG,,}" == "false" ]; then
         sed -ri \
             -e 's!^(\s*access_log).+\;!\1 off\;!g' \
             "/etc/nginx/nginx.conf"
diff --git a/web-nginx-mysql/centos/README.md b/web-nginx-mysql/centos/README.md
index 76571af93..89d375a05 100644
--- a/web-nginx-mysql/centos/README.md
+++ b/web-nginx-mysql/centos/README.md
@@ -14,10 +14,10 @@ Zabbix web interface is a part of Zabbix software. It is used to manage resource
 
 # Zabbix web interface images
 
-These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix web interface are:
+These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix web interface are:
 
-    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix web interface 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix web interface 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix web interface 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/web-nginx-mysql/centos/docker-entrypoint.sh b/web-nginx-mysql/centos/docker-entrypoint.sh
index 964f41825..1e827d21c 100755
--- a/web-nginx-mysql/centos/docker-entrypoint.sh
+++ b/web-nginx-mysql/centos/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -66,17 +66,17 @@ check_variables() {
     file_env MYSQL_USER
     file_env MYSQL_PASSWORD
 
-    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD}" == "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD,,}" == "true" ]; then
         echo "**** Impossible to use MySQL server because of unknown Zabbix user and random 'root' password"
         exit 1
     fi
 
-    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" != "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" != "true" ]; then
         echo "*** Impossible to use MySQL server because 'root' password is not defined and it is not empty"
         exit 1
     fi
 
-    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
+    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
         USE_DB_ROOT_USER=true
         DB_SERVER_ROOT_USER="root"
         DB_SERVER_ROOT_PASS=${MYSQL_ROOT_PASSWORD:-""}
@@ -86,7 +86,7 @@ check_variables() {
 
     # If root password is not specified use provided credentials
     : ${DB_SERVER_ROOT_USER:=${MYSQL_USER}}
-    [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
+    [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
     DB_SERVER_ZBX_USER=${MYSQL_USER:-"zabbix"}
     DB_SERVER_ZBX_PASS=${MYSQL_PASSWORD:-"zabbix"}
 
@@ -96,7 +96,7 @@ check_variables() {
 db_tls_params() {
     local result=""
 
-    if [ "${ZBX_DB_ENCRYPTION}" == "true" ]; then
+    if [ "${ZBX_DB_ENCRYPTION,,}" == "true" ]; then
         result="--ssl-mode=required"
 
         if [ -n "${ZBX_DB_CA_FILE}" ]; then
@@ -120,7 +120,7 @@ check_db_connect() {
     echo "* DB_SERVER_HOST: ${DB_SERVER_HOST}"
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -180,7 +180,8 @@ prepare_zbx_web_config() {
         echo "listen.group = nginx" >> "$PHP_CONFIG_FILE"
     fi
 
-    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS,,}
     export ZBX_GUI_ACCESS_IP_RANGE=${ZBX_GUI_ACCESS_IP_RANGE:-"['127.0.0.1']"}
     export ZBX_GUI_WARNING_MSG=${ZBX_GUI_WARNING_MSG:-"Zabbix is under maintenance."}
 
@@ -202,13 +203,16 @@ prepare_zbx_web_config() {
     export ZBX_SERVER_PORT=${ZBX_SERVER_PORT:-"10051"}
     export ZBX_SERVER_NAME=${ZBX_SERVER_NAME}
 
-    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION,,}
     export ZBX_DB_KEY_FILE=${ZBX_DB_KEY_FILE}
     export ZBX_DB_CERT_FILE=${ZBX_DB_CERT_FILE}
     export ZBX_DB_CA_FILE=${ZBX_DB_CA_FILE}
-    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST-"false"}
+    ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST:-"false"}
+    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST,,}
 
-    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754,,}
 
     export ZBX_HISTORYSTORAGEURL=${ZBX_HISTORYSTORAGEURL}
     export ZBX_HISTORYSTORAGETYPES=${ZBX_HISTORYSTORAGETYPES:-"[]"}
@@ -232,7 +236,9 @@ prepare_zbx_web_config() {
         "$ZABBIX_ETC_DIR/nginx_ssl.conf"
     fi
 
-    if [ "${ENABLE_WEB_ACCESS_LOG:-"true"}" == "false" ]; then
+    ENABLE_WEB_ACCESS_LOG=${ENABLE_WEB_ACCESS_LOG:-"true"}
+
+    if [ "${ENABLE_WEB_ACCESS_LOG,,}" == "false" ]; then
         sed -ri \
             -e 's!^(\s*access_log).+\;!\1 off\;!g' \
             "/etc/nginx/nginx.conf"
diff --git a/web-nginx-mysql/rhel/README.md b/web-nginx-mysql/rhel/README.md
index 0fe77290f..89d375a05 100644
--- a/web-nginx-mysql/rhel/README.md
+++ b/web-nginx-mysql/rhel/README.md
@@ -14,23 +14,25 @@ Zabbix web interface is a part of Zabbix software. It is used to manage resource
 
 # Zabbix web interface images
 
-These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix web interface are:
+These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix web interface are:
 
-    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
-    Zabbix web interface 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2.*) (unsupported)
+    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
+    Zabbix web interface 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix web interface 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
-    Zabbix web interface 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4.*) (unsupported)
+    Zabbix web interface 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
     Zabbix web interface 3.4.* (tags: alpine-3.4.*, ubuntu-3.4.*, centos-3.4.*) (unsupported)
     Zabbix web interface 4.0 (tags: alpine-4.0-latest, ubuntu-4.0-latest, centos-4.0-latest)
     Zabbix web interface 4.0.* (tags: alpine-4.0.*, ubuntu-4.0.*, centos-4.0.*)
-    Zabbix web interface 4.2 (tags: alpine-4.2-latest, ubuntu-4.2-latest, centos-4.2.*) (unsupported)
+    Zabbix web interface 4.2 (tags: alpine-4.2-latest, ubuntu-4.2-latest, centos-4.2-latest) (unsupported)
     Zabbix web interface 4.2.* (tags: alpine-4.2.*, ubuntu-4.2.*, centos-4.2.*) (unsupported)
     Zabbix web interface 4.4 (tags: alpine-4.4-latest, ubuntu-4.4-latest, centos-4.4-latest) (unsupported)
     Zabbix web interface 4.4.* (tags: alpine-4.4.*, ubuntu-4.4.*, centos-4.4.*) (unsupported)
-    Zabbix web interface 5.0 (tags: alpine-5.0-latest, ubuntu-5.0-latest, centos-5.0-latest, alpine-latest, ubuntu-latest, centos-latest, latest)
+    Zabbix web interface 5.0 (tags: alpine-5.0-latest, ubuntu-5.0-latest, centos-5.0-latest)
     Zabbix web interface 5.0.* (tags: alpine-5.0.*, ubuntu-5.0.*, centos-5.0.*)
-    Zabbix web interface 5.2 (tags: alpine-trunk, ubuntu-trunk, centos-trunk)
+    Zabbix web interface 5.2 (tags: alpine-5.2-latest, ubuntu-5.2-latest, centos-5.2-latest, alpine-latest, ubuntu-latest, centos-latest, latest)
+    Zabbix web interface 5.2.* (tags: alpine-5.2.*, ubuntu-5.2.*, centos-5.2.*)
+    Zabbix web interface 5.4 (tags: alpine-trunk, ubuntu-trunk, centos-trunk)
 
 Images are updated when new releases are published. The image with ``latest`` tag is based on Alpine Linux.
 
@@ -128,7 +130,7 @@ Array of value types to be sent to the history storage. An example: ['uint', 'db
 
 ### `PHP_TZ`
 
-The variable is timezone in PHP format. Full list of supported timezones are available on [`php.net`](http://php.net/manual/en/timezones.php). By default, value is 'Europe/Riga'.
+The variable is timezone in PHP format. Full list of supported timezones are available on [`php.net`](http://php.net/manual/en/timezones.php). By default, value is 'Europe/Riga' and system timezone since Zabbix 5.2.0.
 
 ### `ZBX_SERVER_NAME`
 
diff --git a/web-nginx-mysql/rhel/docker-entrypoint.sh b/web-nginx-mysql/rhel/docker-entrypoint.sh
index 964f41825..1e827d21c 100755
--- a/web-nginx-mysql/rhel/docker-entrypoint.sh
+++ b/web-nginx-mysql/rhel/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -66,17 +66,17 @@ check_variables() {
     file_env MYSQL_USER
     file_env MYSQL_PASSWORD
 
-    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD}" == "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD,,}" == "true" ]; then
         echo "**** Impossible to use MySQL server because of unknown Zabbix user and random 'root' password"
         exit 1
     fi
 
-    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" != "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" != "true" ]; then
         echo "*** Impossible to use MySQL server because 'root' password is not defined and it is not empty"
         exit 1
     fi
 
-    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
+    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
         USE_DB_ROOT_USER=true
         DB_SERVER_ROOT_USER="root"
         DB_SERVER_ROOT_PASS=${MYSQL_ROOT_PASSWORD:-""}
@@ -86,7 +86,7 @@ check_variables() {
 
     # If root password is not specified use provided credentials
     : ${DB_SERVER_ROOT_USER:=${MYSQL_USER}}
-    [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
+    [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
     DB_SERVER_ZBX_USER=${MYSQL_USER:-"zabbix"}
     DB_SERVER_ZBX_PASS=${MYSQL_PASSWORD:-"zabbix"}
 
@@ -96,7 +96,7 @@ check_variables() {
 db_tls_params() {
     local result=""
 
-    if [ "${ZBX_DB_ENCRYPTION}" == "true" ]; then
+    if [ "${ZBX_DB_ENCRYPTION,,}" == "true" ]; then
         result="--ssl-mode=required"
 
         if [ -n "${ZBX_DB_CA_FILE}" ]; then
@@ -120,7 +120,7 @@ check_db_connect() {
     echo "* DB_SERVER_HOST: ${DB_SERVER_HOST}"
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -180,7 +180,8 @@ prepare_zbx_web_config() {
         echo "listen.group = nginx" >> "$PHP_CONFIG_FILE"
     fi
 
-    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS,,}
     export ZBX_GUI_ACCESS_IP_RANGE=${ZBX_GUI_ACCESS_IP_RANGE:-"['127.0.0.1']"}
     export ZBX_GUI_WARNING_MSG=${ZBX_GUI_WARNING_MSG:-"Zabbix is under maintenance."}
 
@@ -202,13 +203,16 @@ prepare_zbx_web_config() {
     export ZBX_SERVER_PORT=${ZBX_SERVER_PORT:-"10051"}
     export ZBX_SERVER_NAME=${ZBX_SERVER_NAME}
 
-    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION,,}
     export ZBX_DB_KEY_FILE=${ZBX_DB_KEY_FILE}
     export ZBX_DB_CERT_FILE=${ZBX_DB_CERT_FILE}
     export ZBX_DB_CA_FILE=${ZBX_DB_CA_FILE}
-    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST-"false"}
+    ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST:-"false"}
+    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST,,}
 
-    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754,,}
 
     export ZBX_HISTORYSTORAGEURL=${ZBX_HISTORYSTORAGEURL}
     export ZBX_HISTORYSTORAGETYPES=${ZBX_HISTORYSTORAGETYPES:-"[]"}
@@ -232,7 +236,9 @@ prepare_zbx_web_config() {
         "$ZABBIX_ETC_DIR/nginx_ssl.conf"
     fi
 
-    if [ "${ENABLE_WEB_ACCESS_LOG:-"true"}" == "false" ]; then
+    ENABLE_WEB_ACCESS_LOG=${ENABLE_WEB_ACCESS_LOG:-"true"}
+
+    if [ "${ENABLE_WEB_ACCESS_LOG,,}" == "false" ]; then
         sed -ri \
             -e 's!^(\s*access_log).+\;!\1 off\;!g' \
             "/etc/nginx/nginx.conf"
diff --git a/web-nginx-mysql/ubuntu/README.md b/web-nginx-mysql/ubuntu/README.md
index 76571af93..89d375a05 100644
--- a/web-nginx-mysql/ubuntu/README.md
+++ b/web-nginx-mysql/ubuntu/README.md
@@ -14,10 +14,10 @@ Zabbix web interface is a part of Zabbix software. It is used to manage resource
 
 # Zabbix web interface images
 
-These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix web interface are:
+These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix web interface are:
 
-    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix web interface 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix web interface 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix web interface 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/web-nginx-mysql/ubuntu/docker-entrypoint.sh b/web-nginx-mysql/ubuntu/docker-entrypoint.sh
index 97a5f8fa8..c9f96dd80 100755
--- a/web-nginx-mysql/ubuntu/docker-entrypoint.sh
+++ b/web-nginx-mysql/ubuntu/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -66,17 +66,17 @@ check_variables() {
     file_env MYSQL_USER
     file_env MYSQL_PASSWORD
 
-    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD}" == "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD,,}" == "true" ]; then
         echo "**** Impossible to use MySQL server because of unknown Zabbix user and random 'root' password"
         exit 1
     fi
 
-    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" != "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" != "true" ]; then
         echo "*** Impossible to use MySQL server because 'root' password is not defined and it is not empty"
         exit 1
     fi
 
-    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
+    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
         USE_DB_ROOT_USER=true
         DB_SERVER_ROOT_USER="root"
         DB_SERVER_ROOT_PASS=${MYSQL_ROOT_PASSWORD:-""}
@@ -86,7 +86,7 @@ check_variables() {
 
     # If root password is not specified use provided credentials
     : ${DB_SERVER_ROOT_USER:=${MYSQL_USER}}
-    [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
+    [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
     DB_SERVER_ZBX_USER=${MYSQL_USER:-"zabbix"}
     DB_SERVER_ZBX_PASS=${MYSQL_PASSWORD:-"zabbix"}
 
@@ -96,7 +96,7 @@ check_variables() {
 db_tls_params() {
     local result=""
 
-    if [ "${ZBX_DB_ENCRYPTION}" == "true" ]; then
+    if [ "${ZBX_DB_ENCRYPTION,,}" == "true" ]; then
         result="--ssl-mode=required"
 
         if [ -n "${ZBX_DB_CA_FILE}" ]; then
@@ -120,7 +120,7 @@ check_db_connect() {
     echo "* DB_SERVER_HOST: ${DB_SERVER_HOST}"
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -180,7 +180,8 @@ prepare_zbx_web_config() {
         echo "listen.group = nginx" >> "$PHP_CONFIG_FILE"
     fi
 
-    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS,,}
     export ZBX_GUI_ACCESS_IP_RANGE=${ZBX_GUI_ACCESS_IP_RANGE:-"['127.0.0.1']"}
     export ZBX_GUI_WARNING_MSG=${ZBX_GUI_WARNING_MSG:-"Zabbix is under maintenance."}
 
@@ -202,13 +203,16 @@ prepare_zbx_web_config() {
     export ZBX_SERVER_PORT=${ZBX_SERVER_PORT:-"10051"}
     export ZBX_SERVER_NAME=${ZBX_SERVER_NAME}
 
-    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION,,}
     export ZBX_DB_KEY_FILE=${ZBX_DB_KEY_FILE}
     export ZBX_DB_CERT_FILE=${ZBX_DB_CERT_FILE}
     export ZBX_DB_CA_FILE=${ZBX_DB_CA_FILE}
-    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST-"false"}
+    ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST:-"false"}
+    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST,,}
 
-    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754,,}
 
     export ZBX_HISTORYSTORAGEURL=${ZBX_HISTORYSTORAGEURL}
     export ZBX_HISTORYSTORAGETYPES=${ZBX_HISTORYSTORAGETYPES:-"[]"}
@@ -232,7 +236,9 @@ prepare_zbx_web_config() {
         "$ZABBIX_ETC_DIR/nginx_ssl.conf"
     fi
 
-    if [ "${ENABLE_WEB_ACCESS_LOG:-"true"}" == "false" ]; then
+    ENABLE_WEB_ACCESS_LOG=${ENABLE_WEB_ACCESS_LOG:-"true"}
+
+    if [ "${ENABLE_WEB_ACCESS_LOG,,}" == "false" ]; then
         sed -ri \
             -e 's!^(\s*access_log).+\;!\1 off\;!g' \
             "/etc/nginx/nginx.conf"
diff --git a/web-nginx-pgsql/alpine/README.md b/web-nginx-pgsql/alpine/README.md
index 034679d25..603a90639 100644
--- a/web-nginx-pgsql/alpine/README.md
+++ b/web-nginx-pgsql/alpine/README.md
@@ -14,10 +14,10 @@ Zabbix web interface is a part of Zabbix software. It is used to manage resource
 
 # Zabbix web interface images
 
-These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix web interface are:
+These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix web interface are:
 
-    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix web interface 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix web interface 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix web interface 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/web-nginx-pgsql/alpine/docker-entrypoint.sh b/web-nginx-pgsql/alpine/docker-entrypoint.sh
index b392b254d..7743fb050 100755
--- a/web-nginx-pgsql/alpine/docker-entrypoint.sh
+++ b/web-nginx-pgsql/alpine/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -86,7 +86,7 @@ check_db_connect() {
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
     echo "* DB_SERVER_SCHEMA: ${DB_SERVER_SCHEMA}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -167,7 +167,8 @@ prepare_zbx_web_config() {
         echo "listen.group = nginx" >> "$PHP_CONFIG_FILE"
     fi
 
-    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS,,}
     export ZBX_GUI_ACCESS_IP_RANGE=${ZBX_GUI_ACCESS_IP_RANGE:-"['127.0.0.1']"}
     export ZBX_GUI_WARNING_MSG=${ZBX_GUI_WARNING_MSG:-"Zabbix is under maintenance."}
 
@@ -189,13 +190,16 @@ prepare_zbx_web_config() {
     export ZBX_SERVER_PORT=${ZBX_SERVER_PORT:-"10051"}
     export ZBX_SERVER_NAME=${ZBX_SERVER_NAME}
 
-    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION,,}
     export ZBX_DB_KEY_FILE=${ZBX_DB_KEY_FILE}
     export ZBX_DB_CERT_FILE=${ZBX_DB_CERT_FILE}
     export ZBX_DB_CA_FILE=${ZBX_DB_CA_FILE}
-    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST-"false"}
+    ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST:-"false"}
+    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST,,}
 
-    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754,,}
 
     export ZBX_HISTORYSTORAGEURL=${ZBX_HISTORYSTORAGEURL}
     export ZBX_HISTORYSTORAGETYPES=${ZBX_HISTORYSTORAGETYPES:-"[]"}
@@ -217,7 +221,9 @@ prepare_zbx_web_config() {
         "$ZABBIX_ETC_DIR/nginx_ssl.conf"
     fi
 
-    if [ "${ENABLE_WEB_ACCESS_LOG:-"true"}" == "false" ]; then
+    ENABLE_WEB_ACCESS_LOG=${ENABLE_WEB_ACCESS_LOG:-"true"}
+
+    if [ "${ENABLE_WEB_ACCESS_LOG,,}" == "false" ]; then
         sed -ri \
             -e 's!^(\s*access_log).+\;!\1 off\;!g' \
             "/etc/nginx/nginx.conf"
diff --git a/web-nginx-pgsql/centos/README.md b/web-nginx-pgsql/centos/README.md
index 034679d25..603a90639 100644
--- a/web-nginx-pgsql/centos/README.md
+++ b/web-nginx-pgsql/centos/README.md
@@ -14,10 +14,10 @@ Zabbix web interface is a part of Zabbix software. It is used to manage resource
 
 # Zabbix web interface images
 
-These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix web interface are:
+These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix web interface are:
 
-    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix web interface 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix web interface 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix web interface 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/web-nginx-pgsql/centos/docker-entrypoint.sh b/web-nginx-pgsql/centos/docker-entrypoint.sh
index f5acee22c..2a75059e1 100755
--- a/web-nginx-pgsql/centos/docker-entrypoint.sh
+++ b/web-nginx-pgsql/centos/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -86,7 +86,7 @@ check_db_connect() {
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
     echo "* DB_SERVER_SCHEMA: ${DB_SERVER_SCHEMA}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -167,7 +167,8 @@ prepare_zbx_web_config() {
         echo "listen.group = nginx" >> "$PHP_CONFIG_FILE"
     fi
 
-    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS,,}
     export ZBX_GUI_ACCESS_IP_RANGE=${ZBX_GUI_ACCESS_IP_RANGE:-"['127.0.0.1']"}
     export ZBX_GUI_WARNING_MSG=${ZBX_GUI_WARNING_MSG:-"Zabbix is under maintenance."}
 
@@ -189,13 +190,16 @@ prepare_zbx_web_config() {
     export ZBX_SERVER_PORT=${ZBX_SERVER_PORT:-"10051"}
     export ZBX_SERVER_NAME=${ZBX_SERVER_NAME}
 
-    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION,,}
     export ZBX_DB_KEY_FILE=${ZBX_DB_KEY_FILE}
     export ZBX_DB_CERT_FILE=${ZBX_DB_CERT_FILE}
     export ZBX_DB_CA_FILE=${ZBX_DB_CA_FILE}
-    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST-"false"}
+    ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST:-"false"}
+    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST,,}
 
-    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754,,}
 
     export ZBX_HISTORYSTORAGEURL=${ZBX_HISTORYSTORAGEURL}
     export ZBX_HISTORYSTORAGETYPES=${ZBX_HISTORYSTORAGETYPES:-"[]"}
@@ -217,7 +221,9 @@ prepare_zbx_web_config() {
         "$ZABBIX_ETC_DIR/nginx_ssl.conf"
     fi
 
-    if [ "${ENABLE_WEB_ACCESS_LOG:-"true"}" == "false" ]; then
+    ENABLE_WEB_ACCESS_LOG=${ENABLE_WEB_ACCESS_LOG:-"true"}
+
+    if [ "${ENABLE_WEB_ACCESS_LOG,,}" == "false" ]; then
         sed -ri \
             -e 's!^(\s*access_log).+\;!\1 off\;!g' \
             "/etc/nginx/nginx.conf"
diff --git a/web-nginx-pgsql/ubuntu/README.md b/web-nginx-pgsql/ubuntu/README.md
index 034679d25..603a90639 100644
--- a/web-nginx-pgsql/ubuntu/README.md
+++ b/web-nginx-pgsql/ubuntu/README.md
@@ -14,10 +14,10 @@ Zabbix web interface is a part of Zabbix software. It is used to manage resource
 
 # Zabbix web interface images
 
-These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.11, Ubuntu 18.04 (bionic) and CentOS 7 images. The available versions of Zabbix web interface are:
+These are the only official Zabbix web interface Docker images. They are based on Alpine Linux v3.12, Ubuntu 20.04 (focal) and CentOS 8 images. The available versions of Zabbix web interface are:
 
-    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest)
-    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*)
+    Zabbix web interface 3.0 (tags: alpine-3.0-latest, ubuntu-3.0-latest, centos-3.0-latest) (unsupported)
+    Zabbix web interface 3.0.* (tags: alpine-3.0.*, ubuntu-3.0.*, centos-3.0.*) (unsupported)
     Zabbix web interface 3.2 (tags: alpine-3.2-latest, ubuntu-3.2-latest, centos-3.2-latest) (unsupported)
     Zabbix web interface 3.2.* (tags: alpine-3.2.*, ubuntu-3.2.*, centos-3.2.*) (unsupported)
     Zabbix web interface 3.4 (tags: alpine-3.4-latest, ubuntu-3.4-latest, centos-3.4-latest) (unsupported)
diff --git a/web-nginx-pgsql/ubuntu/docker-entrypoint.sh b/web-nginx-pgsql/ubuntu/docker-entrypoint.sh
index 67f6180ed..fef64a9ec 100755
--- a/web-nginx-pgsql/ubuntu/docker-entrypoint.sh
+++ b/web-nginx-pgsql/ubuntu/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -86,7 +86,7 @@ check_db_connect() {
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
     echo "* DB_SERVER_SCHEMA: ${DB_SERVER_SCHEMA}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -167,7 +167,8 @@ prepare_zbx_web_config() {
         echo "listen.group = nginx" >> "$PHP_CONFIG_FILE"
     fi
 
-    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS,,}
     export ZBX_GUI_ACCESS_IP_RANGE=${ZBX_GUI_ACCESS_IP_RANGE:-"['127.0.0.1']"}
     export ZBX_GUI_WARNING_MSG=${ZBX_GUI_WARNING_MSG:-"Zabbix is under maintenance."}
 
@@ -189,13 +190,16 @@ prepare_zbx_web_config() {
     export ZBX_SERVER_PORT=${ZBX_SERVER_PORT:-"10051"}
     export ZBX_SERVER_NAME=${ZBX_SERVER_NAME}
 
-    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION,,}
     export ZBX_DB_KEY_FILE=${ZBX_DB_KEY_FILE}
     export ZBX_DB_CERT_FILE=${ZBX_DB_CERT_FILE}
     export ZBX_DB_CA_FILE=${ZBX_DB_CA_FILE}
-    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST-"false"}
+    ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST:-"false"}
+    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST,,}
 
-    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754,,}
 
     export ZBX_HISTORYSTORAGEURL=${ZBX_HISTORYSTORAGEURL}
     export ZBX_HISTORYSTORAGETYPES=${ZBX_HISTORYSTORAGETYPES:-"[]"}
@@ -217,7 +221,9 @@ prepare_zbx_web_config() {
         "$ZABBIX_ETC_DIR/nginx_ssl.conf"
     fi
 
-    if [ "${ENABLE_WEB_ACCESS_LOG:-"true"}" == "false" ]; then
+    ENABLE_WEB_ACCESS_LOG=${ENABLE_WEB_ACCESS_LOG:-"true"}
+
+    if [ "${ENABLE_WEB_ACCESS_LOG,,}" == "false" ]; then
         sed -ri \
             -e 's!^(\s*access_log).+\;!\1 off\;!g' \
             "/etc/nginx/nginx.conf"
diff --git a/zabbix-appliance/rhel/docker-entrypoint.sh b/zabbix-appliance/rhel/docker-entrypoint.sh
index d574d98ee..cca41a39b 100755
--- a/zabbix-appliance/rhel/docker-entrypoint.sh
+++ b/zabbix-appliance/rhel/docker-entrypoint.sh
@@ -5,7 +5,7 @@ set -o pipefail
 set +e
 
 # Script trace mode
-if [ "${DEBUG_MODE}" == "true" ]; then
+if [ "${DEBUG_MODE,,}" == "true" ]; then
     set -o xtrace
 fi
 
@@ -202,17 +202,17 @@ check_variables_mysql() {
 
     file_env MYSQL_ROOT_PASSWORD
 
-    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD}" == "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ "${MYSQL_RANDOM_ROOT_PASSWORD,,}" == "true" ]; then
         echo "**** Impossible to use MySQL server because of unknown Zabbix user and random 'root' password"
         exit 1
     fi
 
-    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" != "true" ]; then
+    if [ ! -n "${MYSQL_USER}" ] && [ ! -n "${MYSQL_ROOT_PASSWORD}" ] && [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" != "true" ]; then
         echo "*** Impossible to use MySQL server because 'root' password is not defined and it is not empty"
         exit 1
     fi
 
-    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
+    if [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || [ -n "${MYSQL_ROOT_PASSWORD}" ]; then
         USE_DB_ROOT_USER=true
         DB_SERVER_ROOT_USER="root"
         DB_SERVER_ROOT_PASS=${MYSQL_ROOT_PASSWORD:-""}
@@ -222,7 +222,7 @@ check_variables_mysql() {
 
     # If root password is not specified use provided credentials
     : ${DB_SERVER_ROOT_USER:=${MYSQL_USER}}
-    [ "${MYSQL_ALLOW_EMPTY_PASSWORD}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
+    [ "${MYSQL_ALLOW_EMPTY_PASSWORD,,}" == "true" ] || DB_SERVER_ROOT_PASS=${DB_SERVER_ROOT_PASS:-${MYSQL_PASSWORD}}
     DB_SERVER_ZBX_USER=${MYSQL_USER:-"zabbix"}
     DB_SERVER_ZBX_PASS=${MYSQL_PASSWORD:-"zabbix"}
 
@@ -260,7 +260,7 @@ check_db_connect() {
     echo "* DB_SERVER_HOST: ${DB_SERVER_HOST}"
     echo "* DB_SERVER_PORT: ${DB_SERVER_PORT}"
     echo "* DB_SERVER_DBNAME: ${DB_SERVER_DBNAME}"
-    if [ "${DEBUG_MODE}" == "true" ]; then
+    if [ "${DEBUG_MODE,,}" == "true" ]; then
         if [ "${USE_DB_ROOT_USER}" == "true" ]; then
             echo "* DB_SERVER_ROOT_USER: ${DB_SERVER_ROOT_USER}"
             echo "* DB_SERVER_ROOT_PASS: ${DB_SERVER_ROOT_PASS}"
@@ -450,7 +450,7 @@ update_zbx_config() {
     update_config_var $ZBX_CONFIG "VMwareTimeout" "${ZBX_VMWARETIMEOUT}"
 
     : ${ZBX_ENABLE_SNMP_TRAPS:="false"}
-    if [ "${ZBX_ENABLE_SNMP_TRAPS}" == "true" ]; then
+    if [ "${ZBX_ENABLE_SNMP_TRAPS,,}" == "true" ]; then
         update_config_var $ZBX_CONFIG "SNMPTrapperFile" "${ZABBIX_USER_HOME_DIR}/snmptraps/snmptraps.log"
         update_config_var $ZBX_CONFIG "StartSNMPTrapper" "1"
     else
@@ -538,6 +538,11 @@ prepare_zbx_web_config() {
         echo "listen.group = nginx" >> "$PHP_CONFIG_FILE"
     fi
 
+    ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS:-"false"}
+    export ZBX_DENY_GUI_ACCESS=${ZBX_DENY_GUI_ACCESS,,}
+    export ZBX_GUI_ACCESS_IP_RANGE=${ZBX_GUI_ACCESS_IP_RANGE:-"['127.0.0.1']"}
+    export ZBX_GUI_WARNING_MSG=${ZBX_GUI_WARNING_MSG:-"Zabbix is under maintenance."}
+
     export ZBX_MAXEXECUTIONTIME=${ZBX_MAXEXECUTIONTIME:-"600"}
     export ZBX_MEMORYLIMIT=${ZBX_MEMORYLIMIT:-"128M"}
     export ZBX_POSTMAXSIZE=${ZBX_POSTMAXSIZE:-"16M"}
@@ -556,13 +561,16 @@ prepare_zbx_web_config() {
     export ZBX_SERVER_PORT="10051"
     export ZBX_SERVER_NAME=${ZBX_SERVER_NAME}
 
-    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION:-"false"}
+    export ZBX_DB_ENCRYPTION=${ZBX_DB_ENCRYPTION,,}
     export ZBX_DB_KEY_FILE=${ZBX_DB_KEY_FILE}
     export ZBX_DB_CERT_FILE=${ZBX_DB_CERT_FILE}
     export ZBX_DB_CA_FILE=${ZBX_DB_CA_FILE}
-    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST-"false"}
+    ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST:-"false"}
+    export ZBX_DB_VERIFY_HOST=${ZBX_DB_VERIFY_HOST,,}
 
-    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754:-"true"}
+    export DB_DOUBLE_IEEE754=${DB_DOUBLE_IEEE754,,}
 
     export ZBX_HISTORYSTORAGEURL=${ZBX_HISTORYSTORAGEURL}
     export ZBX_HISTORYSTORAGETYPES=${ZBX_HISTORYSTORAGETYPES:-"[]"}
@@ -586,7 +594,9 @@ prepare_zbx_web_config() {
         "$ZABBIX_ETC_DIR/nginx_ssl.conf"
     fi
 
-    if [ "${ENABLE_WEB_ACCESS_LOG:-"true"}" == "false" ]; then
+    ENABLE_WEB_ACCESS_LOG=${ENABLE_WEB_ACCESS_LOG:-"true"}
+
+    if [ "${ENABLE_WEB_ACCESS_LOG,,}" == "false" ]; then
         sed -ri \
             -e 's!^(\s*access_log).+\;!\1 off\;!g' \
             "/etc/nginx/nginx.conf"