docs: Adding Kotlin example. (#1454)

* Setting up Kotlin environment. Converting test to Kotlin.

* Deploying via SAM successfully.

* Added Kotlin example.

* Removing unused Gradle build file.

* Adding SAM template so can be used as an existing project and Java target compatibility

* Adding SAM template so can be used as an existing project

* Updating guidance to use SAM for build and deploy

* Restructuring separate Java and Kotlin examples.

* Updating core examples readme to represent new structure for Java and Kotlin examples.

* Refactoring application code for efficiency, updating build to cover tests too and is more idiomatic and readme to be more descriptive

* Updating to fix trailing \n

* Updating guidance to be more specific for examples

* Adopting new mechanism for specifying jvm target.

* accommodating new project structure

* Fixing link typo after refactoring

* Setting up Kotlin environment. Converting test to Kotlin.

* Deploying via SAM successfully.

* Added Kotlin example.

* Removing unused Gradle build file.

* Adding SAM template so can be used as an existing project and Java target compatibility

* Adding SAM template so can be used as an existing project

* Updating guidance to use SAM for build and deploy

* Restructuring separate Java and Kotlin examples.

* Updating core examples readme to represent new structure for Java and Kotlin examples.

* Refactoring application code for efficiency, updating build to cover tests too and is more idiomatic and readme to be more descriptive

* Updating to fix trailing \n

* Updating guidance to be more specific for examples

* Adopting new mechanism for specifying jvm target.

* accommodating new project structure

* Fixing link typo after refactoring

* Flattening structure back to original to make merging easier for v2

* Adding build for Kotlin Gradle

* Adding build for Kotlin Gradle - Restructuring Java examples to v1 approach

* Correcting paths

* Adding SNAPSHOT support and local capability for Maven. Testing using Java 1.8

* Reviewed and updated against PR comments.

* Un-commenting examples

---------

Co-authored-by: Jason Harris <harrzjas@amazon.com>
Co-authored-by: Scott Gerring <scottgerring@users.noreply.github.com>

Author: 3 people

.github/workflows/pr_build.yml

@@ -66,11 +66,15 @@ jobs:
           cache: 'maven'
       - name: Build with Maven
         run: mvn -B install --file pom.xml
-      - name: Build Gradle Example
+      - name: Build Gradle Example - Java
         if: ${{ matrix.java == '8' }} # Gradle example can only be built on Java 8
         run: |
           cd examples/powertools-examples-core/gradle
           ./gradlew build
+      - name: Build Gradle Example - Kotlin
+        run: |
+          cd examples/powertools-examples-core/kotlin
+          ./gradlew build
       - name: Setup Terraform
         if: ${{ matrix.java == '11' }}
         uses: hashicorp/setup-terraform@633666f66e0061ca3b725c73b2ec20cd13a8fdd1 #v2.0.3

examples/README.md

@@ -5,10 +5,12 @@ Each example can be copied from its subdirectory and used independently of the r
 
 ## Examples
 
-* [powertools-examples-core](powertools-examples-core) - Demonstrates the core logging, tracing, and metrics modules with different build tools 
-  * [SAM](./powertools-examples-core/sam) 
+* [powertools-examples-core](powertools-examples-core) - Demonstrates the core logging, tracing, and metrics modules with different build tools and languages 
   * [CDK](./powertools-examples-core/cdk)
+  * [Gradle](./powertools-examples-core/gradle)
+  * [SAM](./powertools-examples-core/sam) 
   * [Serverless](./powertools-examples-core/serverless)
+  * [Kotlin](./powertools-examples-core/kotlin)
 * [powertools-examples-idempotency](powertools-examples-idempotency) - An idempotent HTTP API
 * [powertools-examples-parameters](powertools-examples-parameters) - Uses the parameters module to provide runtime parameters to a function
 * [powertools-examples-serialization](powertools-examples-serialization) - Uses the serialization module to serialize and deserialize API Gateway & SQS payloads

examples/powertools-examples-core/README.md

@@ -1,12 +1,13 @@
-#  Powertools for AWS Lambda (Java) - Core Utilities Example
+# Powertools for AWS Lambda (Java) - Core Utilities Example
 
 This project demonstrates the Lambda for Powertools Java module - including 
 [logging](https://docs.powertools.aws.dev/lambda/java/core/logging/),
 [tracing](https://docs.powertools.aws.dev/lambda/java/core/tracing/), and
 [metrics](https://docs.powertools.aws.dev/lambda/java/core/metrics/).
 
-We provide examples for the following infrastructure-as-code tools:
+The example application is the same, and you can now also use Kotlin!
 
+## Java
 * [AWS SAM](sam/) 
 * [AWS CDK](cdk/)
 * [Serverless framework](serverless/)
@@ -16,11 +17,21 @@ We also provide an example showing the integration of SAM, Powertools, and Gradl
 
 * [AWS SAM with a Gradle build](gradle/)
 
-For each of the tools, the example application is the same, and consists of the following files:
+- App.java - Code for the application's Lambda function.
+- AppTests.java - Unit tests for the application code.
+- events - Invocation events that you can use to invoke the function.
 
-- [App.java](sam/src/main/java/helloworld/App.java) - Code for the application's Lambda function.
-- [AppTests.java](sam/src/test/java/helloworld/AppTest.java) - Unit tests for the application code.
-- [events](sam/events/event.json) - Invocation events that you can use to invoke the function.
+Configuration files and deployment process for each tool are described in corresponding README files.
+
+## Kotlin
+
+- [Gradle](kotlin/)
+
+Example application consists of the following files:
+
+- App.kt - Code for the application's Lambda function.
+- AppTests.kt - Unit tests for the application code.
+- events - Invocation events that you can use to invoke the function.
 
 Configuration files and deployment process for each tool are described in corresponding README files.
 
@@ -32,14 +43,13 @@ Once the app is deployed, you can invoke the endpoint like this:
  curl https://[REST-API-ID].execute-api.[REGION].amazonaws.com/Prod/hello/
 ```
 
-The response itself isn't particularly interesting - you will get back some information about your IP address.  If 
+The response itself isn't particularly interesting - you will get back some information about your IP address. If
 you go to the Lambda Console and locate the lambda you have deployed, then click the "Monitoring" tab you will
 be able to find:
 
-* **View X-Ray traces** -  Display the traces captured by the traces module. These include subsegments for the
-different function calls within the example
-* **View Cloudwatch logs** - Display the structured logging output of the example
+- **View X-Ray traces** - Display the traces captured by the traces module. These include subsegments for the
+  different function calls within the example
+- **View Cloudwatch logs** - Display the structured logging output of the example
 
-Likewise, from the CloudWatch dashboard, under **Metrics**, **all metrics**,  you will find the namespaces `Another`
-and `ServerlessAirline`. The values in each of these are published by the code in
-[App.java](sam/src/main/java/helloworld/App.java). 
+Likewise, from the CloudWatch dashboard, under **Metrics**, **all metrics**, you will find the namespaces `Another`
+and `ServerlessAirline`. The values in each of these are published by the code in the respective application's Lambda function.

examples/powertools-examples-core/cdk/README.md

@@ -6,9 +6,9 @@ For general information on the deployed example itself, you can refer to the par
 
 ## Configuration
 CDK uses the following project structure:
-- [app](./app) - stores the source code of your application, which is similar between all examples
-- [infra](./infra) - stores the definition of your infrastructure
-  - [cdk.json](./infra/cdk.json) - tells the CDK Toolkit how to execute your app
+- [app](app) - stores the source code of your application, which is similar between all examples
+- [infra](infra) - stores the definition of your infrastructure
+  - [cdk.json](infra/cdk.json) - tells the CDK Toolkit how to execute your app
   - [CdkApp](./infra/src/main/java/cdk/CdkApp.java) - bootstraps your stack, taking AWS `account` and `region` as input
   - [CdkStack](./infra/src/main/java/cdk/CdkStack.java) - defines the Lambda function to be deployed as well as API Gateway for it.
 

examples/powertools-examples-core/gradle/gradlew.bat

@@ -0,0 +1,38 @@
+#  Powertools for AWS Lambda (Kotlin) - Core Utilities Example
+
+This project demonstrates the Lambda for Powertools Kotlin module deployed using [Serverless Application Model](https://aws.amazon.com/serverless/sam/) with
+[Gradle](https://gradle.org/) running the build. This example is configured for Java 1.8 only; in order to use a newer version, check out the Gradle 
+configuration guide [in the main project README](../../../README.md).
+
+You can also use `sam init` to create a new Gradle-powered Powertools application - choose to use the **AWS Quick Start Templates**,
+and then **Hello World Example with Powertools for AWS Lambda**, **Java 17** runtime, and finally **gradle**.
+
+For general information on the deployed example itself, you can refer to the parent [README](../README.md)
+
+## Configuration
+SAM uses [template.yaml](template.yaml) to define the application's AWS resources.
+This file defines the Lambda function to be deployed as well as API Gateway for it.
+
+The build of the project is managed by Gradle, and configured in [build.gradle.kts](build.gradle.kts)
+. 
+
+## Deploy the sample application
+To get started, you can use the included template with SAM to run the build and deploy to your AWS environment:
+
+```bash
+sam build && sam deploy --guided
+```
+
+Once this is done to deploy the example, check out the instructions for getting started with SAM in 
+[the examples directory](../../README.md)
+
+## Additional notes
+
+You can watch the trace information or log information using the SAM CLI:
+```bash
+# Tail the logs
+sam logs --tail $MY_STACK
+
+# Tail the traces
+sam traces --tail
+```

examples/powertools-examples-core/kotlin/README.md

@@ -0,0 +1,39 @@
+plugins {
+    id("io.freefair.aspectj.post-compile-weaving") version "6.6.3"
+    kotlin("jvm") version "1.9.10"
+}
+
+repositories {
+    mavenLocal()
+    mavenCentral()
+}
+
+dependencies {
+    implementation("com.amazonaws:aws-lambda-java-core:1.2.2")
+    implementation("com.fasterxml.jackson.core:jackson-annotations:2.13.2")
+    implementation("com.fasterxml.jackson.core:jackson-databind:2.13.2.2")
+    implementation("com.amazonaws:aws-lambda-java-events:3.11.0")
+    implementation("com.fasterxml.jackson.datatype:jackson-datatype-jsr310:2.13.2")
+    aspect("software.amazon.lambda:powertools-tracing:1.18.0-SNAPSHOT")
+    aspect("software.amazon.lambda:powertools-logging:1.18.0-SNAPSHOT")
+    aspect("software.amazon.lambda:powertools-metrics:1.18.0-SNAPSHOT")
+    testImplementation("junit:junit:4.13.2")
+    implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
+}
+
+tasks.compileKotlin {
+    kotlinOptions {
+        jvmTarget = "1.8"
+    }
+}
+
+tasks.compileTestKotlin {
+    kotlinOptions {
+        jvmTarget = "1.8"
+    }
+}
+
+// If using JDK 11 or higher, use the following instead:
+//kotlin {
+//    jvmToolchain(11)
+//}