AWS Lambda Function URL Guide (#1365)

* AWS Lambda Function URL Guide

./gradlew mnServerlessFunctionAwsLambdaFunctionUrlBuild

* twitter card

* Remove unused imports, semicolons and non-groovy/kotlin isms

---------

Co-authored-by: Tim Yates <tim.yates@gmail.com>

guides/mn-serverless-function-aws-lambda-function-url/groovy/src/main/groovy/example/micronaut/FunctionRequestHandler.groovy

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+package example.micronaut
+
+import io.micronaut.function.aws.MicronautRequestHandler
+import io.micronaut.json.JsonMapper
+import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyRequestEvent
+import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyResponseEvent
+import jakarta.inject.Inject
+
+class FunctionRequestHandler extends MicronautRequestHandler<APIGatewayProxyRequestEvent, APIGatewayProxyResponseEvent> {
+
+    @Inject
+    JsonMapper objectMapper
+
+    @Override
+    APIGatewayProxyResponseEvent execute(APIGatewayProxyRequestEvent input) {
+        APIGatewayProxyResponseEvent response = new APIGatewayProxyResponseEvent()
+        try {
+            String json = new String(objectMapper.writeValueAsBytes([message: "Hello World"]))
+            response.statusCode = 200
+            response.body = json
+        } catch (IOException e) {
+            response.statusCode = 500
+        }
+        response
+    }
+}

guides/mn-serverless-function-aws-lambda-function-url/groovy/src/test/groovy/example/micronaut/FunctionRequestHandlerSpec.groovy

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+package example.micronaut
+
+import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyRequestEvent
+import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyResponseEvent
+import spock.lang.AutoCleanup
+import spock.lang.Shared
+import spock.lang.Specification
+
+class FunctionRequestHandlerSpec extends Specification {
+
+    @AutoCleanup
+    @Shared
+    FunctionRequestHandler handler = new FunctionRequestHandler()
+
+    void "test Handler"() {
+        given:
+        APIGatewayProxyRequestEvent request = new APIGatewayProxyRequestEvent()
+        request.httpMethod = "GET"
+        request.path = "/"
+
+        when:
+        APIGatewayProxyResponseEvent response = handler.execute(request)
+
+        then:
+        response.getStatusCode().intValue() == 200
+        response.body == '{"message":"Hello World"}'
+    }
+}

guides/mn-serverless-function-aws-lambda-function-url/java/src/main/java/example/micronaut/FunctionRequestHandler.java

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+package example.micronaut;
+
+import io.micronaut.function.aws.MicronautRequestHandler;
+import java.io.IOException;
+import io.micronaut.json.JsonMapper;
+import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyRequestEvent;
+import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyResponseEvent;
+import jakarta.inject.Inject;
+import java.util.Collections;
+
+public class FunctionRequestHandler extends MicronautRequestHandler<APIGatewayProxyRequestEvent, APIGatewayProxyResponseEvent> {
+
+    @Inject
+    JsonMapper objectMapper;
+
+    @Override
+    public APIGatewayProxyResponseEvent execute(APIGatewayProxyRequestEvent input) {
+        APIGatewayProxyResponseEvent response = new APIGatewayProxyResponseEvent();
+        try {
+            String json = new String(objectMapper.writeValueAsBytes(Collections.singletonMap("message", "Hello World")));
+            response.setStatusCode(200);
+            response.setBody(json);
+        } catch (IOException e) {
+            response.setStatusCode(500);
+        }
+        return response;
+    }
+}

guides/mn-serverless-function-aws-lambda-function-url/java/src/test/java/example/micronaut/FunctionRequestHandlerTest.java

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+package example.micronaut;
+
+import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyRequestEvent;
+import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyResponseEvent;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class FunctionRequestHandlerTest {
+
+    private static FunctionRequestHandler handler;
+
+    @BeforeAll
+    public static void setupServer() {
+        handler = new FunctionRequestHandler();
+    }
+
+    @AfterAll
+    public static void stopServer() {
+        if (handler != null) {
+            handler.getApplicationContext().close();
+        }
+    }
+
+    @Test
+    void testHandler() {
+        APIGatewayProxyRequestEvent request = new APIGatewayProxyRequestEvent();
+        request.setHttpMethod("GET");
+        request.setPath("/");
+        APIGatewayProxyResponseEvent response = handler.execute(request);
+        assertEquals(200, response.getStatusCode().intValue());
+        assertEquals("{\"message\":\"Hello World\"}", response.getBody());
+    }
+}

guides/mn-serverless-function-aws-lambda-function-url/kotlin/src/main/kotlin/example/micronaut/FunctionRequestHandler.kt

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+package example.micronaut
+
+import io.micronaut.function.aws.MicronautRequestHandler
+import java.io.IOException
+import io.micronaut.json.JsonMapper
+import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyRequestEvent
+import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyResponseEvent
+import jakarta.inject.Inject
+
+class FunctionRequestHandler : MicronautRequestHandler<APIGatewayProxyRequestEvent, APIGatewayProxyResponseEvent>() {
+
+    @Inject
+    lateinit var objectMapper: JsonMapper
+
+    override fun execute(input: APIGatewayProxyRequestEvent): APIGatewayProxyResponseEvent =
+        APIGatewayProxyResponseEvent().apply {
+            try {
+                val json = String(objectMapper.writeValueAsBytes(mapOf("message" to "Hello World")))
+                statusCode = 200
+                body = json
+            } catch (e: IOException) {
+                statusCode = 500
+            }
+        }
+}

guides/mn-serverless-function-aws-lambda-function-url/kotlin/src/test/kotlin/example/micronaut/FunctionRequestHandlerTest.kt

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+package example.micronaut
+
+import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyRequestEvent
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
+
+class FunctionRequestHandlerTest {
+
+    @Test
+    fun testHandler() {
+        val handler = FunctionRequestHandler()
+        val request = APIGatewayProxyRequestEvent()
+        request.httpMethod = "GET"
+        request.path = "/"
+        val response = handler.execute(request)
+        assertEquals(200, response.statusCode.toInt())
+        assertEquals("{\"message\":\"Hello World\"}", response.body)
+        handler.close()
+    }
+}

guides/mn-serverless-function-aws-lambda-function-url/metadata.json

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+{
+  "title": "AWS Lambda Function URL and a Micronaut function",
+  "intro": "Deploy a Micronaut function to AWS Lambda Java 21 runtime and invoke it with a Lambda function URL.",
+  "authors": ["Sergio del Amo"],
+  "tags": ["aws-lambda-function-url"],
+  "categories": ["AWS Lambda"],
+  "publicationDate": "2023-10-16",
+  "apps": [
+    {
+      "applicationType": "function",
+      "name": "default",
+      "features": ["aws-lambda"]
+    }
+  ]
+}

guides/mn-serverless-function-aws-lambda-function-url/mn-serverless-function-aws-lambda-function-url.adoc

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+common:header-top.adoc[]
+
+In this guide, **we will deploy a Micronaut serverless function to AWS Lambda Java 17 runtime and invoke it with a https://docs.aws.amazon.com/lambda/latest/dg/lambda-urls.html[Lambda function URL]**.
+
+common:gettingStarted.adoc[]
+
+common:requirements.adoc[]
+
+common:completesolution.adoc[]
+
+== Writing the Application
+
+common:cli-or-launch.adoc[]
+
+[source,bash]
+----
+mn create-function-app example.micronaut.micronautguide --features=@features@ --build=@build@ --lang=@lang@
+----
+
+common:build-lang-arguments.adoc[]
+
+If you use https://launch.micronaut.io[Micronaut Launch], select _serverless function_ as application type and add the `aws-lambda` and `aws-lambda-function-url` features.
+
+common:default-package.adoc[]
+
+https://guides.micronaut.io/latest/micronaut-intellij-idea-ide-setup.html[Setup IntelliJ IDEA to develop Micronaut Applications].
+
+== Handler
+
+Create  a class extending https://micronaut-projects.github.io/micronaut-aws/latest/api/io/micronaut/function/aws/MicronautRequestHandler.html[MicronautRequestHandler] and define input and output types.
+
+source:FunctionRequestHandler[]
+
+== Handler Test
+
+Write a test which verifies the function behaviour:
+
+test:FunctionRequestHandlerTest[]
+
+* When you instantiate the Handler, the application context starts.
+* Remember to close your application context when you end your test. You can use your handler to obtain it.
+* Invoke the `execute` method of the handler.
+
+common:testApp.adoc[]
+
+== Lambda
+
+Create a Lambda Function. As a runtime, select Java 17 (Correto).
+
+image::create-function.png[]
+
+Enable **function URLs** and set `Auth Type` as `NONE`.
+
+image::enable-function-url.png[]
+
+=== Upload Code
+
+common:executable-jar.adoc[]
+
+Upload it:
+
+image::upload-function-code.png[]
+
+=== Handler
+
+As Handler, set:
+
+`example.micronaut.FunctionRequestHandler`
+
+image::handler-2.png[]
+
+=== Obtain the Function URL
+
+You can obtain the Function URL in the AWS Console:
+
+image:aws-lambda-function-url.png[]
+
+Invoke it, via a cURL command:
+
+[source, bash]
+----
+% curl -i https://xxxxxxxx.lambda-url.xxxx.on.aws/
+{"message":"Hello World"}
+----
+
+common:next.adoc[]
+
+Read more about:
+
+* https://micronaut-projects.github.io/micronaut-aws/latest/guide/#lambda[Micronaut AWS Lambda Support]
+
+* https://aws.amazon.com/lambda/[AWS Lambda]
+
+common:helpWithMicronaut.adoc[]