Provides AWS Lambda integration patterns for Java with cold start optimization. Use when deploying Java functions to AWS Lambda, choosing between Micronaut and Raw Java approaches, optimizing cold starts below 1 second, configuring API Gateway or ALB integration, or implementing serverless Java appl

AWS Lambda Java Integration Patterns for creating high performance AWS Lambda functions in Java with optimized cold starts. Overview This skill provides complete patterns for AWS Lambda Java development, covering two main approaches: 1. Micronaut Framework Full featured framework with AOT compilation, dependency injection, and cold start < 1s 2. Raw Java Minimal overhead approach with cold start < 500ms Both approaches support API Gateway and ALB integration with production ready configurations. When to Use Deploying Java functions to AWS Lambda Optimizing cold starts below 1 second Choosing between Micronaut and Raw Java approaches Configuring API Gateway or ALB integration Setting up CI/CD pipelines for Java Lambda Instructions 1. Choose Your Approach Approach Cold Start Best For Complexity Micronaut < 1s Complex apps, DI needed, enterprise Medium Raw Java < 500ms Simple handlers, minimal overhead Low Validate : Confirm the approach fits your use case before proceeding. 2. Project Structure Validate : Verify project structure matches the template. 3. Implementation Examples Micronaut Handler Raw Java Handler Validate : Run sam local invoke to verify handler works before deployment. Core Patterns Connection Management Error Handling Best Practices Configuration Memory : Start with 512MB, adjust based on profiling Timeout : Micronaut 10 30s, Raw Java 5 10s Runtime : Java 17 or 21 for best performance Packaging Use Gradle Shadow Plugin or Maven Shade Plugin Exclude unnecessary dependencies Monitoring Enable X Ray tracing for performance analysis Use CloudWatch Insights to track cold vs warm starts Deployment Options Serverless Framework Validate : Run serverless deploy with stage dev first. AWS SAM Validate : Run sam validate before deploying. Constraints and Warnings Java Specific Constraints Reflection : Minimize use; prefer AOT compilation (Micronaut) Classpath scanning : Slows cold start; use explicit configuration Large frameworks : Spring Boot adds significant cold start overhead Common Pitfalls 1. Initialization in handler Causes repeated work on warm invocations 2. Oversized JARs Include only required dependencies 3. Insufficient memory Java needs more memory than Node.js/Python 4. No timeout handling Always set appropriate timeouts References For detailed guidance on specific topics: [Micronaut Lambda](references/micronaut lambda.md) Complete Micronaut setup, AOT configuration, DI optimization [Raw Java Lambda](references/raw java lambda.md) Minimal handler patterns, singleton caching, JAR packaging [Serverless Deployment](references/serverless deployment.md) Serverless Framework, SAM, CI/CD pipelines, provisioned concurrency [Testing Lambda](references/testing lambda.md) JUnit 5, SAM Local, integration testing, performance measurement Examples Example 1: Create a Micronaut Lambda Function Input: Process: 1. Configure Gradle project with Micronaut plugin 2. Create Handler class extending MicronautRequestHandler 3. Implement methods for GET/POST/PUT/DELETE 4. Configure application.yml with AOT optimizations 5. Set up packaging with Shadow plugin 6. Validate : Test locally with SAM CLI before deploying Output: Complete project structure Handler with dependency injection serverless.yml deployment configuration Example 2: Optimize Cold Start for Raw Java Input: Process: 1. Analyze initialization code 2. Move AWS client creation to static fields 3. Reduce dependencies in build.gradle 4. Configure optimized JVM options 5. Consider provisioned concurrency 6. Validate : Measure cold start with CloudWatch metrics after changes Output: Refactored code with singleton pattern Minimized JAR Cold start < 500ms Example 3: Deploy with GitHub Actions Input: Process: 1. Create GitHub Actions workflow 2. Configure Gradle build with Shadow 3. Set up SAM build and deploy 4. Add test stage before deployment 5. Configure environment protection for prod Output: Complete .github/workflows/deploy.yml Multi stage pipeline (dev/staging/prod) Integrated test automation Version Version: 1.0.0

aws-lambda-java-integration