Lambda-Local

Lambda-Local 可以讓 Java 開發者：

• 使用同一套程式碼，可以方便的在自己的電腦開發 AWS Lambda function，不用每次都 Deploy 到 AWS 測試
• 可以透過如 Spring MVC 的方式開發 Rest Service，如：

@LambdaLocal("/lleHelloRestService")
public class HelloRestService extends AbstractLambdaRestService {
    @RestMethod(httpMethod = HttpMethod.GET, path = "/{firstName}/{lastName}")
    public String hello(@RestPath("firstName") String firstName,
                               @RestPath("lastName") String lastName) {
        return String.format("Hello %s, %s!", firstName, lastName);
    }
}

Download

• Using Gradle:

repositories {
    maven { url "https://jitpack.io" }
}

compile 'com.zaoo.lambda-local:lambda-local:{version}'

• Using other build system: https://jitpack.io/#com.zaoo.lambda-local/lambda-local

Requirements

Lambda-Local requires at minimum Java 8.

Usage

A Simple Hello Rest Service

1. Install Lambda-Local in your build file. Ex: Using Gradle:

   repositories {
       maven { url "https://jitpack.io" }
   }
   
   compile 'com.zaoo.lambda-local:lambda-local:{version}'

2. Add a WEB-INF/web.xml.

   <?xml version="1.0" encoding="UTF-8"?>
   <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
            version="3.1">
       <servlet>
           <servlet-name>dispatcher</servlet-name>
           <servlet-class>com.zaoo.lambda.LambdaLocalServlet</servlet-class>
           <load-on-startup>1</load-on-startup>
           <init-param>
               <param-name>packages</param-name>
               <param-value>com.zaoo.lambda.example</param-value>
           </init-param>
       </servlet>
       <servlet-mapping>
           <servlet-name>dispatcher</servlet-name>
           <url-pattern>/</url-pattern>
       </servlet-mapping>
   </web-app>

   Provide your package name as the init-param, and Lambda-Local will scan that package and its sub-package for all classes annotated with '@LambdaLocal'.

3. Create your first AWS Lambda Function Handler.

   1. If you're building JSON REST services, you can extend AbstractLambdaRestService and use annotations to define your REST services by method (Like Spring MVC). Ex:

      @LambdaLocal("/lleHelloRestService")
      public class HelloRestService extends AbstractLambdaRestService {
          @RestMethod(httpMethod = HttpMethod.GET, path = "/{firstName}/{lastName}")
          public String hello(@RestPath("firstName") String firstName,
                              @RestPath("lastName") String lastName) {
              return String.format("Hello %s, %s!", firstName, lastName);
          }
      }

      Please note that:

      • @LambdaLocal.value must be the same as your Lambda Function name.
      • Annotations:
      • @RestPath: The parameter is bound to a URI template variable.
      • Lambda-Local using Jackson to convert Object <-> JSON.

   2. If you have setup AWS Lambda using proxy request, you can extend AbstractLambdaLocalRequestHandler to process the pre-defined proxy request and response.

      @LambdaLocal("/lleHelloLambdaProxy")
      public class HelloLambdaProxy extends AbstractLambdaLocalRequestHandler {
          @Override
          public LambdaProxyResponse handleRequest(LambdaProxyRequest input, Context context) {
              String firstName = input.getQueryStringParameters().get("firstName");
              String lastName = input.getQueryStringParameters().get("lastName");
              return new LambdaProxyResponse(String.format("Hello! %s,%s", firstName, lastName));
          }
      }

   3. You can also use Lambda-Local directly without AbstractLambdaRestService or AbstractLambdaLocalRequestHandler (But with more configurations to do). Please take a look at our sample webapp.

Testing & Running the web app

1. Testing on your local machine. Ex: Using Gradle and Gretty plugin.
   1. In build.gradle, put:

      apply from: 'https://raw.github.com/akhikhl/gretty/master/pluginScripts/gretty.plugin'
      
      gretty {
          servletContainer = 'jetty9'
          contextPath = ''
      }
      

   2. Run the web app on your local machine.

      > ./gradlew appRun
      

   3. Open http://localhost:8080/lleHelloRestService or http://localhost:8080/lleHelloLambdaProxy in your browser. (The path depends on your '@LambdaLocal.value')
2. Running on AWS Lambda and API Gateway
   1. Create a new AWS Lambda Function with default AWS API Gateway settings.
   2. Add {proxy+} to all the subpath of the Lambda Function in API Gateway.

Working example

Please take a look at our sample webapp.