GUACAMOLE-2086: Add Tomcat HealthCheckValve

Dockerfile

@@ -99,8 +99,11 @@ USER guacamole
 # Environment variable defaults
 ENV BAN_ENABLED=true \
     ENABLE_FILE_ENVIRONMENT_PROPERTIES=true \
-    GUACAMOLE_HOME=/etc/guacamole
+    GUACAMOLE_HOME=/etc/guacamole \
+    HEALTH_CHECK_VALVE_ENABLED=true
 
 # Start Guacamole under Tomcat, listening on 0.0.0.0:8080
 EXPOSE 8080
+HEALTHCHECK --interval=60s --timeout=10s --start-period=30s \
+    CMD ["/opt/guacamole/bin/healthcheck.sh"]
 CMD ["/opt/guacamole/bin/entrypoint.sh" ]

guacamole-docker/bin/healthcheck.sh

@@ -0,0 +1,40 @@
+#!/bin/bash -e
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+#
+
+##
+## @fn healthcheck.sh
+##
+## Performs a health check for the Guacamole container. If HEALTH_CHECK_VALVE_ENABLED
+## is set to "true", this script will check the actual health endpoint. Otherwise,
+## it will simply return success and log that health checks are disabled.
+##
+
+
+# Check if health check valve is enabled
+if [ "$HEALTH_CHECK_VALVE_ENABLED" = "true" ]; then
+    # Default health check path (/health)
+    HEALTH_CHECK_PATH="${HEALTH_CHECK_VALVE_PATH:-/health}"
+    # Perform actual health check via curl
+    curl --fail --silent --show-error "http://localhost:8080${HEALTH_CHECK_PATH}" || exit 1
+else
+    # Health check valve is disabled - just return OK
+    echo "Health check valve is disabled. Reporting healthy without actual check."
+    exit 0
+fi

guacamole-docker/environment/HEALTH_CHECK_VALVE_/configure.sh

@@ -0,0 +1,54 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+#
+
+##
+## @fn HEALTH_CHECK_VALVE_/configure.sh
+##
+## Configures Tomcat HealthCheckValve to provide a basic health check endpoint if
+## the HEALTH_CHECK_VALVE_ENABLED environment variable is set to "true".
+
+##
+## Array of all xmlstarlet command-line options necessary to add the
+## HealthCheckValve attributes that correspond to various "HEALTH_CHECK_VALVE_*"
+## environment variables.
+##
+
+declare -a VALVE_ATTRIBUTES=( --insert '/Server/Service/Engine/Host/Valve[not(@className)]' --type attr -n className -v org.apache.catalina.valves.HealthCheckValve )
+
+# Translate all properties supported by HealthCheckValve into corresponding
+# environment variables
+for ATTRIBUTE in \
+    path \
+    checkContainersAvailable; do
+
+    VAR_NAME="HEALTH_CHECK_VALVE_$(echo "$ATTRIBUTE" | sed 's/\([a-z]\)\([A-Z]\)/\1_\2/g' | tr 'a-z' 'A-Z')"
+    if [ -n "${!VAR_NAME}" ]; then
+        VALVE_ATTRIBUTES+=( --insert '/Server/Service/Engine/Host/Valve[@className="org.apache.catalina.valves.HealthCheckValve"]' --type attr -n "$ATTRIBUTE" -v "${!VAR_NAME}" )
+    else
+        echo "Using default HealthCheckValve value for \"$ATTRIBUTE\" attribute."
+    fi
+
+done
+
+# Programmatically add requested HealthCheckValve entry
+xmlstarlet edit --inplace \
+    --insert '/Server/Service/Engine/Host/*' --type elem -n Valve \
+    "${VALVE_ATTRIBUTES[@]}" \
+    "$CATALINA_BASE/conf/server.xml"
+