Quick start Spring Boot

You can use the aws-serverless-java-container library to run a Spring Boot application in AWS Lambda. You can use the library within your Lambda handler to load your Spring Boot application and proxy events to it.

In the repository we have included a sample Spring Boot application to get you started.

Import dependencies

The first step is to import the Spring implementation of the library:

<dependency>
    <groupId>com.amazonaws.serverless</groupId>
    <artifactId>aws-serverless-java-container-spring</artifactId>
    <version>[0.8,)</version>
</dependency>

This will automatically also import the aws-serverless-java-container-core and aws-lambda-java-core libraries.

Create the Lambda handler

In your application package declare a new class that implements Lambda's RequestStreamHandler interface. If you have configured API Gateway with a proxy integration, you can use the built-in POJOs AwsProxyRequest and AwsProxyResponse.

The next step is to declare the container handler object. The library exposes a utility static method that configures a SpringBootLambdaContainerHandler object for AWS proxy events. The method receives a class annotated with Spring Boot's @SpringBootApplication. The object should be declared as a class property and be static. By doing this, Lambda will re-use the instance for subsequent requests.

The handleRequest method of the class can use the handler object we declared in the previous step to send requests to the Spring application.

public class StreamLambdaHandler implements RequestStreamHandler {
    private static SpringBootLambdaContainerHandler<AwsProxyRequest, AwsProxyResponse> handler;
    static {
        try {
            handler = SpringBootLambdaContainerHandler.getAwsProxyHandler(Application.class);
        } catch (ContainerInitializationException e) {
            // if we fail here. We re-throw the exception to force another cold start
            e.printStackTrace();
            throw new RuntimeException("Could not initialize Spring Boot application", e);
        }
    }

    @Override
    public void handleRequest(InputStream inputStream, OutputStream outputStream, Context context)
            throws IOException {
        handler.proxyStream(inputStream, outputStream, context);

        // just in case it wasn't closed by the mapper
        outputStream.close();
    }
}

In our sample application The Application class contains the configuration.

@SpringBootApplication
@ComponentScan(basePackages = "com.amazonaws.serverless.sample.springboot.controller")
public class Application extends SpringBootServletInitializer {

    // silence console logging
    @Value("${logging.level.root:OFF}")
    String message = "";

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

Packaging the application

By default, Spring Boot projects include the spring-boot-maven-plugin and an embedded Tomcat application server. To package the Spring Boot application for AWS Lambda, we do not need the Spring Boot maven plugin and we can configure the shade plugin to exclude the embedded Tomcat - the serverless-java-container library takes its place.

<<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-shade-plugin</artifactId>
            <version>2.3</version>
            <configuration>
                <createDependencyReducedPom>false</createDependencyReducedPom>
            </configuration>
            <executions>
                <execution>
                    <phase>package</phase>
                    <goals>
                        <goal>shade</goal>
                    </goals>
                    <configuration>
                        <artifactSet>
                            <excludes>
                                <exclude>org.apache.tomcat.embed:*</exclude>
                            </excludes>
                        </artifactSet>
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>

Spring profiles

You can enable Spring Profiles (as defined with the @Profile annotation) by using the SpringBootLambdaContainerHandler.activateSpringProfiles(String...) method. Behind the scenes, this method flags the SpringBoot application for re-initialization ands ets the spring.profiles.active environment property. See @Profile documentation for details.

Publish your Lambda function

You can follow the instructions in AWS Lambda's documentation on how to package your function for deployment.