NIFI-9688 Improve Logback shutdown handling (#5805)

* NIFI-9688 Improved Logback shutdown handling
- Added environment variable to disable Logback shutdown on web application termination
- Added shutdown hook to Logback configuration
- Added Logback shutdown hook configuration to system tests

nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-resources/src/main/resources/bin/nifi-env.sh

@@ -50,6 +50,9 @@ export NIFI_PID_DIR
 NIFI_LOG_DIR="$(setOrDefault "$NIFI_LOG_DIR" "$NIFI_HOME/logs")"
 export NIFI_LOG_DIR
 
+# Disable automatic Logback Initializer to avoid shutdown on web application termination
+export logbackDisableServletContainerInitializer="true"
+
 # Set to false to force the use of Keytab controller service in processors
 # that use Kerberos. If true, these processors will allow configuration of keytab
 # and principal directly within the processor. If false, these processors will be

nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-resources/src/main/resources/conf/logback.xml

@@ -15,6 +15,8 @@
 -->
 
 <configuration scan="true" scanPeriod="30 seconds">
+    <shutdownHook class="ch.qos.logback.core.hook.DelayingShutdownHook" />
+
     <contextListener class="ch.qos.logback.classic.jul.LevelChangePropagator">
         <resetJUL>true</resetJUL>
     </contextListener>

nifi-nar-bundles/nifi-framework-bundle/nifi-framework/nifi-web/nifi-web-api/src/main/java/org/apache/nifi/web/contextlistener/ApplicationStartupContextListener.java

@@ -95,9 +95,9 @@ public class ApplicationStartupContextListener implements ServletContextListener
 
     @Override
     public void contextDestroyed(ServletContextEvent sce) {
-        logger.info("Initiating shutdown of flow service...");
+        logger.info("Flow Service shutdown started");
         shutdown();
-        logger.info("Flow service termination completed.");
+        logger.info("Flow Service shutdown completed");
     }
 
     private void shutdown() {

nifi-system-tests/nifi-system-test-suite/src/test/resources/conf/clustered/node1/bootstrap.conf

@@ -30,3 +30,6 @@ java.arg.14=-Djava.awt.headless=true
 #java.arg.debug=-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8002
 
 java.arg.nodeNum=-DnodeNumber=1
+
+# Disable Logback web shutdown hook using System property
+java.arg.logbackShutdown=-DlogbackDisableServletContainerInitializer=true

nifi-system-tests/nifi-system-test-suite/src/test/resources/conf/clustered/node1/logback.xml

@@ -15,6 +15,8 @@
 -->
 
 <configuration scan="true" scanPeriod="30 seconds">
+    <shutdownHook class="ch.qos.logback.core.hook.DelayingShutdownHook" />
+
     <contextListener class="ch.qos.logback.classic.jul.LevelChangePropagator">
         <resetJUL>true</resetJUL>
     </contextListener>

nifi-system-tests/nifi-system-test-suite/src/test/resources/conf/clustered/node2/bootstrap.conf

@@ -30,3 +30,6 @@ java.arg.14=-Djava.awt.headless=true
 #java.arg.debug=-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8003
 
 java.arg.nodeNum=-DnodeNumber=2
+
+# Disable Logback web shutdown hook using System property
+java.arg.logbackShutdown=-DlogbackDisableServletContainerInitializer=true

nifi-system-tests/nifi-system-test-suite/src/test/resources/conf/clustered/node2/logback.xml

@@ -15,6 +15,8 @@
 -->
 
 <configuration scan="true" scanPeriod="30 seconds">
+    <shutdownHook class="ch.qos.logback.core.hook.DelayingShutdownHook" />
+
     <contextListener class="ch.qos.logback.classic.jul.LevelChangePropagator">
         <resetJUL>true</resetJUL>
     </contextListener>

nifi-system-tests/nifi-system-test-suite/src/test/resources/conf/default/bootstrap.conf

@@ -28,3 +28,6 @@ java.arg.3=-Xmx512m
 java.arg.14=-Djava.awt.headless=true
 
 #java.arg.debug=-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=8002
+
+# Disable Logback web shutdown hook using System property
+java.arg.logbackShutdown=-DlogbackDisableServletContainerInitializer=true

nifi-system-tests/nifi-system-test-suite/src/test/resources/conf/default/logback.xml

@@ -15,6 +15,8 @@
 -->
 
 <configuration scan="true" scanPeriod="30 seconds">
+    <shutdownHook class="ch.qos.logback.core.hook.DelayingShutdownHook" />
+
     <contextListener class="ch.qos.logback.classic.jul.LevelChangePropagator">
         <resetJUL>true</resetJUL>
     </contextListener>