AWS SDK for Java 2.x - AWS Lambda

Overview

AWS Lambda is a compute service that runs code without managing servers. Use this skill to implement AWS Lambda operations using AWS SDK for Java 2.x in applications and services.

When to Use

• Invoking Lambda functions from Java applications
• Deploying and updating Lambda functions via SDK
• Managing function configurations and layers
• Integrating Lambda with Spring Boot applications

Quick Reference

| Operation | SDK Method | Use Case | |-----------|------------|----------| | Invoke | invoke() | Synchronous/async function invocation | | List Functions | listFunctions() | Get all Lambda functions | | Get Config | getFunction() | Retrieve function configuration | | Create Function | createFunction() | Create new Lambda function | | Update Code | updateFunctionCode() | Deploy new function code | | Update Config | updateFunctionConfiguration() | Modify settings (timeout, memory, env vars) | | Delete Function | deleteFunction() | Remove Lambda function |

Instructions

1. Add Dependencies

Include Lambda SDK dependency in pom.xml:

xml
<dependency>
    <groupId>software.amazon.awssdk</groupId>
    <artifactId>lambda</artifactId>
</dependency>

See client-setup.md for complete setup.

2. Create Client

Instantiate LambdaClient with proper configuration:

java
LambdaClient lambdaClient = LambdaClient.builder()
    .region(Region.US_EAST_1)
    .build();

For async operations, use LambdaAsyncClient.

3. Invoke Lambda Function

Synchronous invocation:

java
InvokeRequest request = InvokeRequest.builder()
    .functionName("my-function")
    .payload(SdkBytes.fromUtf8String(payload))
    .build();

InvokeResponse response = lambdaClient.invoke(request);

return response.payload().asUtf8String();

See invocation-patterns.md for patterns.

4. Handle Responses

Parse response payloads and check for errors:

java
if (response.functionError() != null) {
    throw new LambdaInvocationException("Lambda error: " + response.functionError());
}

String result = response.payload().asUtf8String();

5. Manage Functions

Create, update, or delete Lambda functions:

java
// Create
CreateFunctionRequest createRequest = CreateFunctionRequest.builder()
    .functionName("my-function")
    .runtime(Runtime.JAVA17)
    .role(roleArn)
    .code(code)
    .build();

lambdaClient.createFunction(createRequest);

// Verify function is active before proceeding
GetFunctionRequest getRequest = GetFunctionRequest.builder()
    .functionName("my-function")
    .build();
GetFunctionResponse getResponse = lambdaClient.getFunction(getRequest);
if (!"Active".equals(getResponse.configuration().state())) {
    throw new IllegalStateException("Function not active: " + getResponse.configuration().stateReason());
}

// Update code
UpdateFunctionCodeRequest updateCodeRequest = UpdateFunctionCodeRequest.builder()
    .functionName("my-function")
    .zipFile(SdkBytes.fromByteArray(zipBytes))
    .build();

lambdaClient.updateFunctionCode(updateCodeRequest);

// Wait for deployment to complete
Waiter<GetFunctionConfigurationRequest> waiter = lambdaClient.waiter();
waiter.waitUntilFunctionUpdatedActive(GetFunctionConfigurationRequest.builder()
    .functionName("my-function")
    .build());

See function-management.md for complete patterns.

6. Configure Environment

Set environment variables and concurrency limits:

java
Environment env = Environment.builder()
    .variables(Map.of(
        "DB_URL", "jdbc:postgresql://db",
        "LOG_LEVEL", "INFO"
    ))
    .build();

UpdateFunctionConfigurationRequest configRequest = UpdateFunctionConfigurationRequest.builder()
    .functionName("my-function")
    .environment(env)
    .timeout(60)
    .memorySize(512)
    .build();

lambdaClient.updateFunctionConfiguration(configRequest);

7. Integrate with Spring Boot

Configure Lambda beans and services:

java
@Configuration
public class LambdaConfiguration {
    @Bean
    public LambdaClient lambdaClient() {
        return LambdaClient.builder()
            .region(Region.US_EAST_1)
            .build();
    }
}

@Service
public class LambdaInvokerService {
    public <T, R> R invoke(String functionName, T request, Class<R> responseType) {
        // Implementation
    }
}

See spring-boot-integration.md for complete integration.

8. Test Locally

Use mocks or LocalStack for development testing.

See testing.md for testing patterns.

Examples

Basic Invocation

java
public String invokeFunction(LambdaClient client, String functionName, String payload) {
    InvokeRequest request = InvokeRequest.builder()
        .functionName(functionName)
        .payload(SdkBytes.fromUtf8String(payload))
        .build();

    InvokeResponse response = client.invoke(request);

    if (response.functionError() != null) {
        throw new RuntimeException("Lambda error: " + response.functionError());
    }

    return response.payload().asUtf8String();
}

Async Invocation

java
public void invokeAsync(LambdaClient client, String functionName, Map<String, Object> event) {
    String jsonPayload = new ObjectMapper().writeValueAsString(event);

    InvokeRequest request = InvokeRequest.builder()
        .functionName(functionName)
        .invocationType(InvocationType.EVENT)
        .payload(SdkBytes.fromUtf8String(jsonPayload))
        .build();

    client.invoke(request);
}

Spring Boot Service

java
@Service
public class LambdaService {
    private final LambdaClient lambdaClient;

    public UserResponse processUser(UserRequest request) {
        String payload = objectMapper.writeValueAsString(request);

        InvokeResponse response = lambdaClient.invoke(
            InvokeRequest.builder()
                .functionName("user-processor")
                .payload(SdkBytes.fromUtf8String(payload))
                .build()
        );

        return objectMapper.readValue(
            response.payload().asUtf8String(),
            UserResponse.class
        );
    }
}

See examples.md for more examples.

Best Practices

• Reuse clients: Create LambdaClient/LambdaAsyncClient once; they are thread-safe
• Use async client: For fire-and-forget invocations, use LambdaAsyncClient with CompletableFuture
• Verify deployments: Always wait for function state to be Active after create/update operations
• Limit payload size: Keep request/response payloads under 256KB for async, 6MB for sync invocations
• Configure timeouts: Set client read timeout slightly higher than Lambda function timeout
• Use latest runtime: Specify Runtime.JAVA17 or newer for improved cold start performance

Constraints and Warnings

• Payload Limit: 6MB (sync), 256KB (async invocation)
• Timeout: Max 900 seconds (15 minutes) per invocation
• Cold Starts: JVM-based functions have longer cold starts; use GraalVM Native Image for improvement
• Deployment Size: Function code + layers must not exceed 50MB (zipped) or 250MB (unzipped)
• Concurrency: Default 1000 per region; use reserved concurrency to guarantee capacity
• Cost: Monitor with CloudWatch metrics; set billing alerts to prevent runaway costs

References

• client-setup.md — Client configuration and setup
• invocation-patterns.md — Synchronous and async invocation patterns
• function-management.md — Create, update, delete functions
• spring-boot-integration.md — Spring Boot configuration and services
• testing.md — Unit and integration testing patterns
• examples.md — Complete code examples and integration patterns
• official-documentation.md — AWS Lambda concepts and API reference

Related Skills

• aws-sdk-java-v2-core — Core AWS SDK patterns and client configuration
• spring-boot-dependency-injection — Spring dependency injection best practices
• unit-test-service-layer — Service testing patterns with Mockito
• spring-boot-actuator — Production monitoring and health checks

External Resources

• Lambda Examples on GitHub
• Lambda API Reference
• AWS Lambda Developer Guide