[alc] Log4j2 support (#37) (#454)

* [alc] Log4j2 support

* [log4j2] bump aws-lambda-java-core deps to 1.2.3

* [log4j2] version bump and doc updates

---------

Co-authored-by: Daniel Torok <torokd@amazon.com>

Author: dtorok

README.md

@@ -21,7 +21,7 @@ Example request handler
 public class Handler implements RequestHandler<Map<String, String>, String>{
  @Override
  public String handleRequest(Map<String, String> event, Context context) {
- 
+
  }
 }
 ```
@@ -32,7 +32,7 @@ Example request stream handler
 public class HandlerStream implements RequestStreamHandler {
   @Override
   public void handleRequest(InputStream inputStream, OutputStream outputStream, Context context) throws IOException {
-    
+
   }
 }
 ```
@@ -101,7 +101,7 @@ public void testInjectSQSEvent(SQSEvent event) {
 ## aws-lambda-java-events-sdk-transformer
 
 This package provides helper classes/methods to use alongside `aws-lambda-java-events` in order to transform
-Lambda input event model objects into SDK-compatible output model objects.  
+Lambda input event model objects into SDK-compatible output model objects.
 See the [documentation](aws-lambda-java-events-sdk-transformer/README.md) for more information.
 
 - [Release Notes](aws-lambda-java-events-sdk-transformer/RELEASE.CHANGELOG.md)
@@ -125,7 +125,7 @@ See the [README](aws-lambda-java-log4j2/README.md) or the [official documentatio
 <dependency>
  <groupId>com.amazonaws</groupId>
  <artifactId>aws-lambda-java-log4j2</artifactId>
- <version>1.5.1</version>
+ <version>1.6.0</version>
 </dependency>
 ```
 

aws-lambda-java-log4j2/README.md

@@ -10,7 +10,7 @@ Example for Maven pom.xml
   <dependency>
     <groupId>com.amazonaws</groupId>
     <artifactId>aws-lambda-java-log4j2</artifactId>
-    <version>1.5.1</version>
+    <version>1.6.0</version>
   </dependency>
   <dependency>
     <groupId>org.apache.logging.log4j</groupId>
@@ -65,10 +65,10 @@ If using maven shade plugin, set the plugin configuration as follows
 If you are using the [John Rengelman](https://github.com/johnrengelman/shadow) Gradle shadow plugin, then the plugin configuration is as follows:
 
 ```groovy
- 
+
 dependencies{
   ...
-    implementation group: 'com.amazonaws', name: 'aws-lambda-java-log4j2', version: '1.5.1'
+    implementation group: 'com.amazonaws', name: 'aws-lambda-java-log4j2', version: '1.6.0'
     implementation group: 'org.apache.logging.log4j', name: 'log4j-core', version: log4jVersion
     implementation group: 'org.apache.logging.log4j', name: 'log4j-api', version: log4jVersion
 }
@@ -83,8 +83,8 @@ shadowJar {
 build.dependsOn(shadowJar)
 
 ```
- 
-If you are using the `sam build` and `sam deploy` commands to deploy your lambda function, then you don't 
+
+If you are using the `sam build` and `sam deploy` commands to deploy your lambda function, then you don't
 need to use the shadow jar plugin. The `sam` cli-tool merges itself the `Log4j2Plugins.dat`
 files.
 
@@ -94,12 +94,17 @@ Add the following file `<project-dir>/src/main/resources/log4j2.xml`
 
 ```xml
 <?xml version="1.0" encoding="UTF-8"?>
-<Configuration packages="com.amazonaws.services.lambda.runtime.log4j2">
+<Configuration>
   <Appenders>
-    <Lambda name="Lambda">
-      <PatternLayout>
+    <Lambda name="Lambda" format="${env:AWS_LAMBDA_LOG_FORMAT:-TEXT}">
+      <LambdaTextFormat>
+        <PatternLayout>
           <pattern>%d{yyyy-MM-dd HH:mm:ss} %X{AWSRequestId} %-5p %c{1}:%L - %m%n</pattern>
-      </PatternLayout>
+        </PatternLayout>
+      </LambdaTextFormat>
+      <LambdaJSONFormat>
+        <JsonTemplateLayout eventTemplateUri="classpath:LambdaLayout.json" />
+      </LambdaJSONFormat>
     </Lambda>
   </Appenders>
   <Loggers>
@@ -110,6 +115,8 @@ Add the following file `<project-dir>/src/main/resources/log4j2.xml`
 </Configuration>
 ```
 
+If the `AWS_LAMBDA_LOG_FORMAT` is set to `JSON`, the `LambdaJSONFormat` formatter will be applied, otherwise the `LambdaTextFormat`.
+
 ### 3. Example code
 
 ```java

aws-lambda-java-log4j2/RELEASE.CHANGELOG.md

@@ -1,3 +1,7 @@
+### October 24, 2023
+`1.6.0`:
+- Log level and log format support
+
 ### January 04, 2022
 `1.5.1`:
 - Updated `log4j-core` and `log4j-api` dependencies to `2.17.1`

aws-lambda-java-log4j2/pom.xml

@@ -5,7 +5,7 @@
 
     <groupId>com.amazonaws</groupId>
     <artifactId>aws-lambda-java-log4j2</artifactId>
-    <version>1.5.1</version>
+    <version>1.6.0</version>
     <packaging>jar</packaging>
 
     <name>AWS Lambda Java Log4j 2.x Libraries</name>
@@ -48,7 +48,7 @@
         <dependency>
             <groupId>com.amazonaws</groupId>
             <artifactId>aws-lambda-java-core</artifactId>
-            <version>1.2.2</version>
+            <version>1.2.3</version>
         </dependency>
         <dependency>
             <groupId>org.apache.logging.log4j</groupId>

aws-lambda-java-log4j2/src/main/java/com/amazonaws/services/lambda/runtime/log4j2/LambdaAppender.java

@@ -2,16 +2,24 @@
 
 import com.amazonaws.services.lambda.runtime.LambdaRuntime;
 import com.amazonaws.services.lambda.runtime.LambdaRuntimeInternal;
+
 import com.amazonaws.services.lambda.runtime.LambdaLogger;
+import com.amazonaws.services.lambda.runtime.logging.LogFormat;
+import com.amazonaws.services.lambda.runtime.logging.LogLevel;
 
+import org.apache.logging.log4j.Level;
 import org.apache.logging.log4j.core.Filter;
 import org.apache.logging.log4j.core.Layout;
 import org.apache.logging.log4j.core.LogEvent;
 import org.apache.logging.log4j.core.appender.AbstractAppender;
 import org.apache.logging.log4j.core.config.plugins.Plugin;
+import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
 import org.apache.logging.log4j.core.config.plugins.PluginBuilderFactory;
+import org.apache.logging.log4j.core.config.plugins.PluginElement;
 
 import java.io.Serializable;
+import java.util.HashMap;
+import java.util.Map;
 
 /**
  * Class to append log4j2 logs from AWS Lambda function to CloudWatch
@@ -20,27 +28,53 @@
 @Plugin(name = LambdaAppender.PLUGIN_NAME, category = LambdaAppender.PLUGIN_CATEGORY,
         elementType = LambdaAppender.PLUGIN_TYPE, printObject = true)
 public class LambdaAppender extends AbstractAppender {
+    static {
+        LambdaRuntimeInternal.setUseLog4jAppender(true);
+    }
 
     public static final String PLUGIN_NAME = "Lambda";
     public static final String PLUGIN_CATEGORY = "Core";
     public static final String PLUGIN_TYPE = "appender";
 
     private LambdaLogger logger = LambdaRuntime.getLogger();
 
+    private static LogFormat logFormat = LogFormat.TEXT;
+
+    private static final Map<Level, LogLevel> logLevelMapper = new HashMap<Level, LogLevel>() {{
+        put(Level.TRACE, LogLevel.TRACE);
+        put(Level.DEBUG, LogLevel.DEBUG);
+        put(Level.INFO, LogLevel.INFO);
+        put(Level.WARN, LogLevel.WARN);
+        put(Level.ERROR, LogLevel.ERROR);
+        put(Level.FATAL, LogLevel.FATAL);
+    }};
+
     /**
      * Builder class that follows log4j2 plugin convention
      * @param <B> Generic Builder class
      */
     public static class Builder<B extends Builder<B>> extends AbstractAppender.Builder<B>
             implements org.apache.logging.log4j.core.util.Builder<LambdaAppender> {
 
+        @PluginAttribute(value = "format", defaultString = "TEXT")
+        LogFormat logFormat;
+        @PluginElement("LambdaTextFormat")
+        private LambdaTextFormat lambdaTextFormat;
+        @PluginElement("LambdaJsonFormat")
+        private LambdaJsonFormat lambdaJsonFormat;
+
         /**
          * creates a new LambdaAppender
          * @return a new LambdaAppender
          */
         public LambdaAppender build() {
-            return new LambdaAppender(super.getName(), super.getFilter(), super.getOrCreateLayout(),
-                    super.isIgnoreExceptions());
+            Layout<?> layout;
+            if (logFormat == LogFormat.TEXT) {
+                layout = lambdaTextFormat != null ? lambdaTextFormat.getLayout() : super.getOrCreateLayout();
+            } else {
+                layout = lambdaJsonFormat != null ? lambdaJsonFormat.getLayout() : super.getOrCreateLayout();
+            }
+            return new LambdaAppender(super.getName(), super.getFilter(), layout, super.isIgnoreExceptions());
         }
     }
 
@@ -63,14 +97,22 @@ public static <B extends Builder<B>> B newBuilder() {
      */
     private LambdaAppender(String name, Filter filter, Layout<? extends Serializable> layout, boolean ignoreExceptions) {
         super(name, filter, layout, ignoreExceptions);
-        LambdaRuntimeInternal.setUseLog4jAppender(true);
+    }
+
+    /**
+     * Converts log4j Level into Lambda LogLevel
+     * @param level the log4j log level
+     * @return Lambda log leve
+     */
+    private LogLevel toLambdaLogLevel(Level level) {
+        return logLevelMapper.getOrDefault(level, LogLevel.UNDEFINED);
     }
 
     /**
      * Append log event to System.out
      * @param event log4j event
      */
     public void append(LogEvent event) {
-        logger.log(super.getLayout().toByteArray(event));
+        logger.log(getLayout().toByteArray(event), toLambdaLogLevel(event.getLevel()));
     }
 }

aws-lambda-java-log4j2/src/main/java/com/amazonaws/services/lambda/runtime/log4j2/LambdaJsonFormat.java

@@ -0,0 +1,29 @@
+/* Copyright 2023 Amazon.com, Inc. or its affiliates. All Rights Reserved. */
+
+package com.amazonaws.services.lambda.runtime.log4j2;
+
+import org.apache.logging.log4j.core.Layout;
+import org.apache.logging.log4j.core.config.plugins.Plugin;
+import org.apache.logging.log4j.core.config.plugins.PluginElement;
+import org.apache.logging.log4j.core.config.plugins.PluginFactory;
+
+import java.io.Serializable;
+
+@Plugin(name = "LambdaJsonFormat", category = "core", printObject = true)
+public class LambdaJsonFormat {
+
+    private Layout layout;
+
+    @PluginFactory
+    public static LambdaJsonFormat createNode(@PluginElement("Layout") Layout<? extends Serializable> layout) {
+        return new LambdaJsonFormat(layout);
+    }
+
+    private LambdaJsonFormat(Layout layout) {
+        this.layout = layout;
+    }
+
+    public Layout getLayout() {
+        return layout;
+    }
+}

aws-lambda-java-log4j2/src/main/java/com/amazonaws/services/lambda/runtime/log4j2/LambdaTextFormat.java

@@ -0,0 +1,29 @@
+/* Copyright 2023 Amazon.com, Inc. or its affiliates. All Rights Reserved. */
+
+package com.amazonaws.services.lambda.runtime.log4j2;
+
+import org.apache.logging.log4j.core.Layout;
+import org.apache.logging.log4j.core.config.plugins.Plugin;
+import org.apache.logging.log4j.core.config.plugins.PluginElement;
+import org.apache.logging.log4j.core.config.plugins.PluginFactory;
+
+import java.io.Serializable;
+
+@Plugin(name = "LambdaTextFormat", category = "core", printObject = true)
+public class LambdaTextFormat {
+
+    private Layout layout;
+
+    @PluginFactory
+    public static LambdaTextFormat createNode(@PluginElement("Layout") Layout<? extends Serializable> layout) {
+        return new LambdaTextFormat(layout);
+    }
+
+    private LambdaTextFormat(Layout layout) {
+        this.layout = layout;
+    }
+
+    public Layout getLayout() {
+        return layout;
+    }
+}

aws-lambda-java-log4j2/src/main/resources/LambdaLayout.json

@@ -0,0 +1,39 @@
+{
+  "timestamp": {
+    "$resolver": "timestamp",
+    "pattern": {
+      "format": "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'",
+      "timeZone": "UTC"
+    }
+  },
+  "level": {
+    "$resolver": "level",
+    "field": "name"
+  },
+  "message": {
+    "$resolver": "message"
+  },
+  "logger": {
+    "$resolver": "logger",
+    "field": "name"
+  },
+
+  "errorType": {
+    "$resolver": "exception",
+    "field": "className"
+  },
+  "errorMessage": {
+    "$resolver": "exception",
+    "field": "message"
+  },
+  "stackTrace": {
+    "$resolver": "exception",
+    "field": "stackTrace"
+  },
+
+  "labels": {
+    "$resolver": "mdc",
+    "flatten": true,
+    "stringified": true
+  }
+}