Eliminate hard-coded JAR path

Author: paltamadura

cdk/build.gradle

@@ -12,10 +12,11 @@ repositories {
 
 application {
     mainClassName = 'com.davidagood.cdkjava.CdkJavaApp'
+    applicationDefaultJvmArgs = ['-Dgreeting.language=en', "-DlambdaJar=${project(':lambda').name}"] //"
 }
 
 dependencies {
-    implementation project(':lambda')
+    runtimeOnly project(':lambda')
     implementation 'software.amazon.awscdk:core:1.62.0'
     implementation 'software.amazon.awscdk:dynamodb:1.62.0'
     implementation 'software.amazon.awscdk:lambda:1.62.0'
@@ -24,7 +25,7 @@ dependencies {
 
 group = 'com.davidagood'
 version = '0.1'
-sourceCompatibility = '1.8'
+sourceCompatibility = '11'
 
 tasks.withType(JavaCompile) {
     options.encoding = 'UTF-8'

cdk/src/main/java/com/davidagood/cdkjava/CdkJavaStack.java

@@ -10,6 +10,12 @@
 import software.amazon.awscdk.services.lambda.Function;
 import software.amazon.awscdk.services.lambda.Runtime;
 
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.URL;
+
+import static java.util.Objects.isNull;
+
 public class CdkJavaStack extends Stack {
     public CdkJavaStack(final Construct parent, final String id) {
         this(parent, id, null);
@@ -23,12 +29,33 @@ public CdkJavaStack(final Construct parent, final String id, final StackProps pr
                 .sortKey(Attribute.builder().name("SK").type(AttributeType.STRING).build())
                 .build();
 
-        Code codeFromLocalPath = Code.fromAsset("/Users/davidgood/dev/cdk-java-gradle-multi-module/lambda/build/libs/lambda-uber.jar");
+        URI uri;
+
+        try {
+            URL url = getClass().getResource("/liba");
+
+            if (isNull(url)) {
+                throw new RuntimeException("Executable JAR not found in classpath resources");
+            }
 
-        Function function = Function.Builder.create(this, "test-func-cdk")
-                .code(codeFromLocalPath)
+            uri = url.toURI();
+
+            System.out.println("Full URI for classpath resource \"/lib\": " + uri);
+        } catch (URISyntaxException e) {
+            throw new RuntimeException(e);
+        }
+
+        // We expect the URI to be in this format
+        // jar:file:/home/dgood/IdeaProjects/cdk-java-starter/lambda/build_lambda/lambda.jar!/lib
+        // Not sure of a better way to get the absolute path of the JAR
+        String lambdaExecutableJarPath = uri.toString().split("jar:file:")[1].split("!")[0];
+        System.out.println("Lambda executable JAR path: " + lambdaExecutableJarPath);
+
+        Function function = Function.Builder.create(this, "ExampleJavaLambda")
+                .code(Code.fromAsset(lambdaExecutableJarPath))
                 .handler("com.davidagood.cdkjava.ExampleHandler::handleRequest")
-                .runtime(Runtime.JAVA_8)
+                .runtime(Runtime.JAVA_11)
                 .build();
     }
+
 }

lambda/.gitignore

@@ -1,3 +1,5 @@
+build_lambda/
+
 # IntelliJ
 .idea/
 *.iml

lambda/build.gradle

@@ -21,20 +21,41 @@ test {
     useJUnitPlatform()
 }
 
+def buildLambdaPath = "${projectDir}/build_lambda"
+
 jar {
     manifest {
         attributes 'Main-Class': 'com.davidagood.cdkjava.ExampleHandler'
     }
+
+    destinationDir file(buildLambdaPath)
+
+    from compileJava
+    from processResources
+
+    // AWS Lambda seems to require the code to be in the lib directory
+    into('lib') {
+        from configurations.runtimeClasspath
+    }
+
 }
 
-// https://docs.gradle.org/current/userguide/working_with_files.html#sec:creating_uber_jar_example
-task uberJar(type: Jar) {
-    archiveClassifier = 'uber'
+// Based on https://github.com/xword/java-npm-gradle-integration-example
+// declare a dedicated scope for publishing the packaged JAR
+configurations {
+    lambdaResources
+}
 
-    from sourceSets.main.output
+configurations.default.extendsFrom(configurations.lambdaResources)
 
-    dependsOn configurations.runtimeClasspath
-    from {
-        configurations.runtimeClasspath.findAll { it.name.endsWith('jar') }.collect { zipTree(it) }
+// expose the artifact created by the packaging task
+artifacts {
+    lambdaResources(jar.archivePath) {
+        builtBy jar
+        type 'jar'
     }
+}
+
+clean {
+    delete buildLambdaPath
 }

lambda/src/main/java/com/davidagood/cdkjava/ExampleHandler.java

@@ -14,15 +14,12 @@ public class ExampleHandler implements RequestHandler<Map<String, String>, Strin
 
     @Override
     public String handleRequest(Map<String, String> event, Context context) {
-
         LambdaLogger logger = context.getLogger();
-        String response = new String("200 OK");
-        // log execution details
+        logger.log("Processed by CDK using a runtime module dependency");
         logger.log("ENVIRONMENT VARIABLES: " + gson.toJson(System.getenv()));
         logger.log("CONTEXT: " + gson.toJson(context));
-        // process event
         logger.log("EVENT: " + gson.toJson(event));
         logger.log("EVENT TYPE: " + event.getClass().toString());
-        return response;
+        return "200 OK";
     }
 }

settings.gradle

@@ -1,13 +1,4 @@
-/*
- * This file was generated by the Gradle 'init' task.
- *
- * The settings file is used to specify which projects to include in your build.
- *
- * Detailed information about configuring a multi-project build in Gradle can be found
- * in the user manual at https://docs.gradle.org/6.2.2/userguide/multi_project_builds.html
- */
-
 rootProject.name = 'cdk-java-gradle-multi-module'
 
-include 'lambda'
-include 'cdk'
+include 'cdk'
+include 'lambda'