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AWS SDK for Java 2.x - AWS Lambda

When to Use

Use this skill when:

Invoking Lambda functions programmatically
Creating or updating Lambda functions
Managing Lambda function configurations
Working with Lambda environment variables
Managing Lambda layers and aliases
Implementing asynchronous Lambda invocations
Integrating Lambda with Spring Boot

Overview

AWS Lambda is a compute service that runs code without the need to manage servers. Your code runs automatically, scaling up and down with pay-per-use pricing. Use this skill to implement AWS Lambda operations using AWS SDK for Java 2.x in applications and services.

Dependencies

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

Client Setup

To use AWS Lambda, create a LambdaClient with the required region configuration:

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.lambda.LambdaClient;

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

For asynchronous operations, use LambdaAsyncClient:

import software.amazon.awssdk.services.lambda.LambdaAsyncClient;

LambdaAsyncClient asyncLambdaClient = LambdaAsyncClient.builder()
    .region(Region.US_EAST_1)
    .build();

Invoke Lambda Function

Synchronous Invocation

Invoke Lambda functions synchronously to get immediate results:

import software.amazon.awssdk.services.lambda.model.*;
import software.amazon.awssdk.core.SdkBytes;

public String invokeLambda(LambdaClient lambdaClient,
                           String functionName,
                           String payload) {
    InvokeRequest request = InvokeRequest.builder()
        .functionName(functionName)
        .payload(SdkBytes.fromUtf8String(payload))
        .build();

    InvokeResponse response = lambdaClient.invoke(request);

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

Asynchronous Invocation

Use asynchronous invocation for fire-and-forget scenarios:

public void invokeLambdaAsync(LambdaClient lambdaClient,
                              String functionName,
                              String payload) {
    InvokeRequest request = InvokeRequest.builder()
        .functionName(functionName)
        .invocationType(InvocationType.EVENT) // Asynchronous
        .payload(SdkBytes.fromUtf8String(payload))
        .build();

    InvokeResponse response = lambdaClient.invoke(request);

    System.out.println("Status: " + response.statusCode());
}

Invoke with JSON Objects

Work with JSON payloads for complex data structures:

import com.fasterxml.jackson.databind.ObjectMapper;

public <T> String invokeLambdaWithObject(LambdaClient lambdaClient,
                                         String functionName,
                                         T requestObject) throws Exception {
    ObjectMapper mapper = new ObjectMapper();
    String jsonPayload = mapper.writeValueAsString(requestObject);

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

    InvokeResponse response = lambdaClient.invoke(request);

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

Parse Typed Responses

Parse JSON responses into typed objects:

public <T> T invokeLambdaAndParse(LambdaClient lambdaClient,
                                  String functionName,
                                  Object request,
                                  Class<T> responseType) throws Exception {
    ObjectMapper mapper = new ObjectMapper();
    String jsonPayload = mapper.writeValueAsString(request);

    InvokeRequest invokeRequest = InvokeRequest.builder()
        .functionName(functionName)
        .payload(SdkBytes.fromUtf8String(jsonPayload))
        .build();

    InvokeResponse response = lambdaClient.invoke(invokeRequest);

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

    return mapper.readValue(responseJson, responseType);
}

Function Management

List Functions

List all Lambda functions for the current account:

public List<FunctionConfiguration> listFunctions(LambdaClient lambdaClient) {
    ListFunctionsResponse response = lambdaClient.listFunctions();

    return response.functions();
}

Get Function Configuration

Retrieve function configuration and metadata:

public FunctionConfiguration getFunctionConfig(LambdaClient lambdaClient,
                                                String functionName) {
    GetFunctionRequest request = GetFunctionRequest.builder()
        .functionName(functionName)
        .build();

    GetFunctionResponse response = lambdaClient.getFunction(request);

    return response.configuration();
}

Update Function Code

Update Lambda function code with new deployment package:

import java.nio.file.Files;
import java.nio.file.Paths;

public void updateFunctionCode(LambdaClient lambdaClient,
                               String functionName,
                               String zipFilePath) throws IOException {
    byte[] zipBytes = Files.readAllBytes(Paths.get(zipFilePath));

    UpdateFunctionCodeRequest request = UpdateFunctionCodeRequest.builder()
        .functionName(functionName)
        .zipFile(SdkBytes.fromByteArray(zipBytes))
        .publish(true)
        .build();

    UpdateFunctionCodeResponse response = lambdaClient.updateFunctionCode(request);

    System.out.println("Updated function version: " + response.version());
}

Update Function Configuration

Modify function settings like timeout, memory, and environment variables:

public void updateFunctionConfiguration(LambdaClient lambdaClient,
                                        String functionName,
                                        Map<String, String> environment) {
    Environment env = Environment.builder()
        .variables(environment)
        .build();

    UpdateFunctionConfigurationRequest request = UpdateFunctionConfigurationRequest.builder()
        .functionName(functionName)
        .environment(env)
        .timeout(60)
        .memorySize(512)
        .build();

    lambdaClient.updateFunctionConfiguration(request);
}

Create Function

Create new Lambda functions with code and configuration:

public void createFunction(LambdaClient lambdaClient,
                          String functionName,
                          String roleArn,
                          String handler,
                          String zipFilePath) throws IOException {
    byte[] zipBytes = Files.readAllBytes(Paths.get(zipFilePath));

    FunctionCode code = FunctionCode.builder()
        .zipFile(SdkBytes.fromByteArray(zipBytes))
        .build();

    CreateFunctionRequest request = CreateFunctionRequest.builder()
        .functionName(functionName)
        .runtime(Runtime.JAVA17)
        .role(roleArn)
        .handler(handler)
        .code(code)
        .timeout(60)
        .memorySize(512)
        .build();

    CreateFunctionResponse response = lambdaClient.createFunction(request);

    System.out.println("Function ARN: " + response.functionArn());
}

Delete Function

Remove Lambda functions when no longer needed:

public void deleteFunction(LambdaClient lambdaClient, String functionName) {
    DeleteFunctionRequest request = DeleteFunctionRequest.builder()
        .functionName(functionName)
        .build();

    lambdaClient.deleteFunction(request);
}

Spring Boot Integration

Configuration

Configure Lambda clients as Spring beans:

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class LambdaConfiguration {

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

Lambda Invoker Service

Create a service for Lambda function invocation:

import org.springframework.stereotype.Service;
import org.springframework.beans.factory.annotation.Autowired;

@Service
public class LambdaInvokerService {

    private final LambdaClient lambdaClient;
    private final ObjectMapper objectMapper;

    @Autowired
    public LambdaInvokerService(LambdaClient lambdaClient, ObjectMapper objectMapper) {
        this.lambdaClient = lambdaClient;
        this.objectMapper = objectMapper;
    }

    public <T, R> R invoke(String functionName, T request, Class<R> responseType) {
        try {
            String jsonPayload = objectMapper.writeValueAsString(request);

            InvokeRequest invokeRequest = InvokeRequest.builder()
                .functionName(functionName)
                .payload(SdkBytes.fromUtf8String(jsonPayload))
                .build();

            InvokeResponse response = lambdaClient.invoke(invokeRequest);

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

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

            return objectMapper.readValue(responseJson, responseType);

        } catch (Exception e) {
            throw new RuntimeException("Failed to invoke Lambda function", e);
        }
    }

    public void invokeAsync(String functionName, Object request) {
        try {
            String jsonPayload = objectMapper.writeValueAsString(request);

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

            lambdaClient.invoke(invokeRequest);

        } catch (Exception e) {
            throw new RuntimeException("Failed to invoke Lambda function async", e);
        }
    }
}

Typed Lambda Client

Create type-safe interfaces for Lambda services:

public interface OrderProcessor {
    OrderResponse processOrder(OrderRequest request);
}

@Service
public class LambdaOrderProcessor implements OrderProcessor {

    private final LambdaInvokerService lambdaInvoker;

    @Value("${lambda.order-processor.function-name}")
    private String functionName;

    public LambdaOrderProcessor(LambdaInvokerService lambdaInvoker) {
        this.lambdaInvoker = lambdaInvoker;
    }

    @Override
    public OrderResponse processOrder(OrderRequest request) {
        return lambdaInvoker.invoke(functionName, request, OrderResponse.class);
    }
}

Error Handling

Implement comprehensive error handling for Lambda operations:

public String invokeLambdaSafe(LambdaClient lambdaClient,
                               String functionName,
                               String payload) {
    try {
        InvokeRequest request = InvokeRequest.builder()
            .functionName(functionName)
            .payload(SdkBytes.fromUtf8String(payload))
            .build();

        InvokeResponse response = lambdaClient.invoke(request);

        // Check for function error
        if (response.functionError() != null) {
            String errorMessage = response.payload().asUtf8String();
            throw new RuntimeException("Lambda error: " + errorMessage);
        }

        // Check status code
        if (response.statusCode() != 200) {
            throw new RuntimeException("Lambda invocation failed with status: " +
                response.statusCode());
        }

        return response.payload().asUtf8String();

    } catch (LambdaException e) {
        System.err.println("Lambda error: " + e.awsErrorDetails().errorMessage());
        throw e;
    }
}

public class LambdaInvocationException extends RuntimeException {
    public LambdaInvocationException(String message) {
        super(message);
    }

    public LambdaInvocationException(String message, Throwable cause) {
        super(message, cause);
    }
}

Examples

For comprehensive code examples, see the references section:

Basic examples - Simple invocation patterns and function management
Spring Boot integration - Complete Spring Boot configuration and service patterns
Testing examples - Unit and integration test patterns
Advanced patterns - Complex scenarios and best practices

Best Practices

Reuse Lambda clients: Create once and reuse across invocations
Set appropriate timeouts: Match client timeout to Lambda function timeout
Use async invocation: For fire-and-forget scenarios
Handle errors properly: Check for function errors and status codes
Use environment variables: For function configuration
Implement retry logic: For transient failures
Monitor invocations: Use CloudWatch metrics
Version functions: Use aliases and versions for production
Use VPC: For accessing resources in private subnets
Optimize payload size: Keep payloads small for better performance

Testing

Test Lambda services using mocks and test assertions:

import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.junit.jupiter.MockitoExtension;

@ExtendWith(MockitoExtension.class)
class LambdaInvokerServiceTest {

    @Mock
    private LambdaClient lambdaClient;

    @Mock
    private ObjectMapper objectMapper;

    @InjectMocks
    private LambdaInvokerService service;

    @Test
    void shouldInvokeLambdaSuccessfully() throws Exception {
        // Test implementation
    }
}

@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

References

For detailed information and examples, see the following reference files:

Official Documentation - AWS Lambda concepts, API reference, and official guidance
Examples - Complete code examples and integration patterns

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