https://github.com/adambien/aws-lambda-cdk-plain

Simplest Possible AWS Lambda Function with Cloud Development Kit (CDK) Boilerplate
https://github.com/adambien/aws-lambda-cdk-plain

aws aws-lambda corretto devops iac infrastructure-as-code java lambda lambda-functions serverless

Last synced: 2 months ago
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Simplest Possible AWS Lambda Function with Cloud Development Kit (CDK) Boilerplate

• Host: GitHub
• URL: https://github.com/adambien/aws-lambda-cdk-plain
• Owner: AdamBien
• License: mit
• Created: 2021-09-30T07:28:13.000Z (over 3 years ago)
• Default Branch: main
• Last Pushed: 2024-05-08T12:45:02.000Z (9 months ago)
• Last Synced: 2024-05-08T13:42:52.482Z (9 months ago)
• Topics: aws, aws-lambda, corretto, devops, iac, infrastructure-as-code, java, lambda, lambda-functions, serverless
• Language: Java
• Homepage:
• Size: 44.9 KB
• Stars: 20
• Watchers: 4
• Forks: 9
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# Simplest Possible AWS Lambda Function with Cloud Development Kit (CDK) Boilerplate

A lean starting point for building, testing and deploying AWS Lambdas with Java.

# TL;DR

A simple Java AWS Lambda without any AWS dependencies:

```java

public class Greetings{

    public String onEvent(Map input) {

        System.out.println("received: " + input);

        return input

        .entrySet()

        .stream()

        .map(e -> e.getKey() + "->" + e.getValue())

        .collect(Collectors.joining(","));

    }

    

}

```

...deployed with AWS Cloud Development Kit:

```java

import software.amazon.awscdk.services.lambda.Code;

import software.amazon.awscdk.services.lambda.Function;

import software.amazon.awscdk.services.lambda.Runtime;

//...

Function createUserListenerFunction(String functionName,String functionHandler, int memory, int timeout) {

    return Function.Builder.create(this, id(functionName))

            .runtime(Runtime.JAVA_11) //https://aws.amazon.com/corretto

            .code(Code.fromAsset("../target/function.jar"))

            .handler(functionHandler)

            .memorySize(memory)

            .functionName(functionName)

            .timeout(Duration.seconds(timeout))

            .build();

}

```

...provisioned with maven and cdk:

```

mvn clean package

cd cdk && mvn clean package && cdk deploy

```

...and (blackbox) tested with [AWS SDK for Java 2.x](https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide):

```java

@BeforeEach

public void initClient() {

    var credentials = DefaultCredentialsProvider

    .builder()

    .profileName("airhacks.live")

    .build();

    this.client = LambdaClient.builder()

                   .credentialsProvider(credentials)

                   .build();

}

@Test

public void invokeLambdaAsynchronously() {

        String json = "{\"user \":\"duke\"}";

        SdkBytes payload = SdkBytes.fromUtf8String(json);

        InvokeRequest request = InvokeRequest.builder()

                .functionName("airhacks_lambda_greetings_boundary_Greetings")

                .payload(payload)

                .invocationType(InvocationType.REQUEST_RESPONSE)

                .build();

        var response = this.client.invoke(request);

        var error = response.functionError();

        assertNull(error);

        var value = response.payload().asUtf8String();

        System.out.println("Function executed. Response: " + value);

}    

```

## In Action

[![Plain Java POJOs as AWS Lambdas](https://i.ytimg.com/vi/rHq514-1aHM/mqdefault.jpg)](https://www.youtube.com/embed/rHq514-1aHM?rel=0)

## Java "vs." JavaScript

Cold and "warm" starts of JavaScript and Java Lambdas:

[![Java vs. JavaScript comparison](https://i.ytimg.com/vi/28Da0l0MFms/mqdefault.jpg)](https://www.youtube.com/embed/28Da0l0MFms?rel=0)

## AWS Lambda on Java: How Good / Bad Is The Cold Start?

[![Coldstart with Java](https://i.ytimg.com/vi/EXSZ5TFgUKU/mqdefault.jpg)](https://www.youtube.com/embed/EXSZ5TFgUKU?rel=0)

## Lambda Configuration

[![AWS Lambda Configuration with Java CDK](https://i.ytimg.com/vi/Z3Ir-AQEsKk/mqdefault.jpg)](https://www.youtube.com/embed/Z3Ir-AQEsKk?rel=0)

## References

The deployment is borrowed from: ["Slightly Streamlined AWS Cloud Development Kit (CDK) Boilerplate"](https://github.com/AdamBien/aws-cdk-plain)