Add requiresLocation function for FailoverAppender (#3257)

Author: eldwrjwt

log4j-core-test/src/test/java/org/apache/logging/log4j/core/appender/FailoverAppenderTest.java

@@ -18,6 +18,7 @@
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.util.List;
 import org.apache.logging.log4j.Logger;
@@ -27,33 +28,14 @@
 import org.apache.logging.log4j.core.test.appender.ListAppender;
 import org.apache.logging.log4j.core.test.junit.LoggerContextSource;
 import org.apache.logging.log4j.core.test.junit.Named;
-import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Test;
 
-@LoggerContextSource("log4j-failover.xml")
 public class FailoverAppenderTest {
-    private final ListAppender app;
-    private final FailOnceAppender foApp;
-    private final Logger logger;
-    private final Logger onceLogger;
-
-    public FailoverAppenderTest(
-            final LoggerContext context,
-            @Named("List") final ListAppender app,
-            @Named("Once") final FailOnceAppender foApp) {
-        this.app = app;
-        this.foApp = foApp;
-        logger = context.getLogger("LoggerTest");
-        onceLogger = context.getLogger("Once");
-    }
-
-    @AfterEach
-    public void tearDown() throws Exception {
-        app.clear();
-    }
 
     @Test
-    public void testFailover() {
+    @LoggerContextSource("log4j-failover.xml")
+    public void testFailover(final LoggerContext context, @Named("List") final ListAppender app) {
+        final Logger logger = context.getLogger("LoggerTest");
         logger.error("This is a test");
         List<LogEvent> events = app.getEvents();
         assertNotNull(events);
@@ -66,7 +48,13 @@ public void testFailover() {
     }
 
     @Test
-    public void testRecovery() throws Exception {
+    @LoggerContextSource("log4j-failover.xml")
+    public void testRecovery(
+            final LoggerContext context,
+            @Named("List") final ListAppender app,
+            @Named("Once") final FailOnceAppender foApp)
+            throws Exception {
+        final Logger onceLogger = context.getLogger("Once");
         onceLogger.error("Fail once");
         onceLogger.error("Fail again");
         List<LogEvent> events = app.getEvents();
@@ -81,4 +69,11 @@ public void testRecovery() throws Exception {
         events = foApp.drainEvents();
         assertEquals(events.size(), 2, "Incorrect number of events in primary appender");
     }
+
+    @Test
+    @LoggerContextSource("log4j-failover-location.xml")
+    public void testRequiresLocation(final LoggerContext context) {
+        final FailoverAppender appender = context.getConfiguration().getAppender("Failover");
+        assertTrue(appender.requiresLocation());
+    }
 }

log4j-core-test/src/test/resources/log4j-failover-location.xml

@@ -0,0 +1,40 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ 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.
+  -->
+<Configuration status="OFF" name="RoutingTest">
+
+    <Appenders>
+        <Console name="CONSOLE">
+            <PatternLayout pattern="%m%L%n"/>
+        </Console>
+        <Console name="CONSOLE2">
+            <PatternLayout pattern="%m%L%n"/>
+        </Console>
+        <Failover name="Failover" primary="CONSOLE">
+            <Failovers>
+                <AppenderRef ref="CONSOLE2"/>
+            </Failovers>
+        </Failover>
+    </Appenders>
+
+    <Loggers>
+        <Root level="debug" includeLocation="true">
+            <AppenderRef ref="Failover"/>
+        </Root>
+    </Loggers>
+
+</Configuration>

log4j-core/src/main/java/org/apache/logging/log4j/core/appender/FailoverAppender.java

@@ -34,6 +34,7 @@
 import org.apache.logging.log4j.core.config.plugins.PluginConfiguration;
 import org.apache.logging.log4j.core.config.plugins.PluginElement;
 import org.apache.logging.log4j.core.config.plugins.PluginFactory;
+import org.apache.logging.log4j.core.impl.LocationAware;
 import org.apache.logging.log4j.core.util.Booleans;
 import org.apache.logging.log4j.core.util.Constants;
 
@@ -223,4 +224,20 @@ public static FailoverAppender createAppender(
         return new FailoverAppender(
                 name, filter, primary, failovers, retryIntervalMillis, config, ignoreExceptions, null);
     }
+
+    @Override
+    public boolean requiresLocation() {
+        if (primary != null
+                && primary.getAppender() instanceof LocationAware
+                && ((LocationAware) primary.getAppender()).requiresLocation()) {
+            return true;
+        }
+        for (final AppenderControl control : failoverAppenders) {
+            final Appender appender = control.getAppender();
+            if (appender instanceof LocationAware && ((LocationAware) appender).requiresLocation()) {
+                return true;
+            }
+        }
+        return false;
+    }
 }

src/changelog/.2.x.x/3257_fix_FailoverAppender_requiresLocation.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<entry xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+       xmlns="https://logging.apache.org/xml/ns"
+       xsi:schemaLocation="https://logging.apache.org/xml/ns https://logging.apache.org/xml/ns/log4j-changelog-0.xsd"
+       type="fixed">
+    <issue id="3257" link="https://github.com/apache/logging-log4j2/issues/3257"/>
+    <description format="asciidoc">Fix detection of location requirements in `FailoverAppender`.</description>
+</entry>