Make Appender detection independent of plugin name.

Author: phipag

powertools-logging/powertools-logging-log4j/src/main/java/software/amazon/lambda/powertools/logging/log4j/internal/Log4jLoggingManager.java

@@ -14,7 +14,8 @@
 
 package software.amazon.lambda.powertools.logging.log4j.internal;
 
-import static software.amazon.lambda.powertools.logging.log4j.Log4jConstants.BUFFERING_APPENDER_PLUGIN_NAME;
+import java.util.Collection;
+import java.util.stream.Collectors;
 
 import org.apache.logging.log4j.Level;
 import org.apache.logging.log4j.LogManager;
@@ -57,24 +58,23 @@ public org.slf4j.event.Level getLogLevel(Logger logger) {
      */
     @Override
     public void flushBuffer() {
-        LoggerContext ctx = (LoggerContext) LogManager.getContext(false);
-        BufferingAppender bufferingAppender = (BufferingAppender) ctx.getConfiguration()
-                .getAppender(BUFFERING_APPENDER_PLUGIN_NAME);
-        if (bufferingAppender != null) {
-            bufferingAppender.flushBuffer();
-        }
+        getBufferingAppenders().forEach(BufferingAppender::flushBuffer);
     }
 
     /**
      * @inheritDoc
      */
     @Override
     public void clearBuffer() {
+        getBufferingAppenders().forEach(BufferingAppender::clearBuffer);
+    }
+
+    private Collection<BufferingAppender> getBufferingAppenders() {
+        // Search all buffering appenders to avoid relying on the appender name given by the user
         LoggerContext ctx = (LoggerContext) LogManager.getContext(false);
-        BufferingAppender bufferingAppender = (BufferingAppender) ctx.getConfiguration()
-                .getAppender(BUFFERING_APPENDER_PLUGIN_NAME);
-        if (bufferingAppender != null) {
-            bufferingAppender.clearBuffer();
-        }
+        return ctx.getConfiguration().getAppenders().values().stream()
+                .filter(BufferingAppender.class::isInstance)
+                .map(BufferingAppender.class::cast)
+                .collect(Collectors.toList());
     }
 }

powertools-logging/powertools-logging-log4j/src/test/java/software/amazon/lambda/powertools/logging/log4j/internal/Log4jLoggingManagerTest.java

@@ -5,6 +5,20 @@
 import static org.slf4j.event.Level.ERROR;
 import static org.slf4j.event.Level.WARN;
 
+import java.io.File;
+import java.io.IOException;
+import java.nio.channels.FileChannel;
+import java.nio.file.NoSuchFileException;
+import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.core.LoggerContext;
+import org.apache.logging.log4j.core.config.Configuration;
+import org.apache.logging.log4j.core.config.ConfigurationFactory;
+import org.apache.logging.log4j.core.config.ConfigurationSource;
+import org.apache.logging.log4j.core.config.xml.XmlConfigurationFactory;
+import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Order;
 import org.junit.jupiter.api.Test;
 import org.slf4j.Logger;
@@ -47,4 +61,45 @@ void resetLogLevel() {
         assertThat(rootLevel).isEqualTo(ERROR);
         assertThat(logLevel).isEqualTo(ERROR);
     }
+
+    @Test
+    void shouldDetectMultipleBufferingAppendersRegardlessOfName() throws IOException {
+        // Given - configuration with multiple BufferingAppenders with different names
+        try {
+            FileChannel.open(Paths.get("target/logfile.json"), StandardOpenOption.WRITE).truncate(0).close();
+        } catch (NoSuchFileException e) {
+            // may not be there in the first run
+        }
+
+        ConfigurationFactory factory = new XmlConfigurationFactory();
+        ConfigurationSource source = new ConfigurationSource(
+                getClass().getResourceAsStream("/log4j2-multiple-buffering.xml"));
+        Configuration config = factory.getConfiguration(null, source);
+
+        LoggerContext ctx = (LoggerContext) LogManager.getContext(false);
+        ctx.setConfiguration(config);
+        ctx.updateLoggers();
+
+        org.apache.logging.log4j.Logger logger = LogManager.getLogger("test.multiple.appenders");
+
+        // When - log messages and flush buffers
+        logger.debug("Test message 1");
+        logger.debug("Test message 2");
+
+        Log4jLoggingManager manager = new Log4jLoggingManager();
+        manager.flushBuffer();
+
+        // Then - both appenders should have flushed their buffers
+        File logFile = new File("target/logfile.json");
+        assertThat(logFile).exists();
+    }
+
+    @AfterEach
+    void cleanUp() throws IOException {
+        try {
+            FileChannel.open(Paths.get("target/logfile.json"), StandardOpenOption.WRITE).truncate(0).close();
+        } catch (NoSuchFileException e) {
+            // may not be there
+        }
+    }
 }

powertools-logging/powertools-logging-log4j/src/test/resources/log4j2-multiple-buffering.xml

@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Configuration>
+    <Appenders>
+        <File name="testFile" fileName="target/logfile.json">
+            <PatternLayout pattern="%msg%n" />
+        </File>
+        <BufferingAppender name="FirstBufferingAppender"
+            bufferAtVerbosity="DEBUG"
+            maxBytes="1024"
+            flushOnErrorLog="true">
+            <AppenderRef ref="testFile" />
+        </BufferingAppender>
+        <BufferingAppender name="SecondBufferingAppender"
+            bufferAtVerbosity="DEBUG"
+            maxBytes="1024"
+            flushOnErrorLog="true">
+            <AppenderRef ref="testFile" />
+        </BufferingAppender>
+    </Appenders>
+    <Loggers>
+        <Logger name="test.multiple.appenders" level="DEBUG" additivity="false">
+            <AppenderRef ref="FirstBufferingAppender" />
+            <AppenderRef ref="SecondBufferingAppender" />
+        </Logger>
+    </Loggers>
+</Configuration>