🚀 Spring Boot AWS Lambda API Gateway

A Serverless REST API built using Spring Boot 3, AWS Lambda, and API Gateway, deployed with Terraform and tested locally using LocalStack.

This project demonstrates how to deploy a Java Spring Boot application as an AWS Lambda function integrated with API Gateway.

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🧠 Overview

This demo showcases:

• ☁️ Serverless Spring Boot REST API running on AWS Lambda
• 🌐 API Gateway integration using Terraform
• 🧰 Local testing with LocalStack

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🧩 Tech Stack

Spring Boot 3.5.7 · Java 21 · Terraform · Docker/Podman · LocalStack · AWS Lambda · API Gateway · S3

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⚙️ Prerequisites

Install the following:

• Java 21
• Maven
• Terraform
• Docker or Podman
• LocalStack CLI (pip install localstack)

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🚀 Build and Deploy

1️⃣ Start LocalStack

docker-compose up -d

2️⃣ Build the Application

mvn clean package

Generates the build at:

target/springboot-aws-lambda-api-gateway-1.0-SNAPSHOT.zip

3️⃣ Deploy using Terraform

tflocal init
tflocal plan -var-file="terraform.tfvars"
tflocal apply -var-file="terraform.tfvars" -auto-approve

terraform init
terraform plan -var-file="terraform.tfvars"
terraform apply -var-file="terraform.tfvars" -auto-approve

4️⃣ Test the API

Check the output URL from Terraform and invoke:

curl http://localhost:4566/restapis/<api_id>/prod/_user_request_/health
curl https://n19xfyl2d4.execute-api.ap-south-1.amazonaws.com/prod/health

🧰 Common Commands & Descriptions

Command	Description
mvn clean package -Pshaded-jar	Builds a fat JAR (single executable JAR) using the shaded profile. This includes all dependencies in one JAR, ideal for AWS Lambda deployments.
mvn clean package -Passembly-zip	Builds a ZIP package (containing compiled classes + dependencies in /lib) using the assembly profile. Useful when Lambda expects a ZIP deployment artifact.
awslocal lambda invoke --function-name SpringBootLambdaFunction out.json	Invokes your deployed Lambda function on LocalStack and writes the response to the file out.json. Helps verify Lambda works before API Gateway setup.
awslocal logs tail /aws/lambda/SpringBootLambdaFunction --follow	Streams real-time Lambda logs from LocalStack to your terminal, similar to aws logs tail. Useful for debugging function initialization and runtime errors.
tflocal init	Initializes the Terraform environment for LocalStack, downloading necessary providers and setting up the workspace.
tflocal plan -var-file="terraform.tfvars"	Generates and displays an execution plan showing which resources Terraform will create or modify in LocalStack.
tflocal apply -var-file="terraform.tfvars" -auto-approve	Applies the Terraform configuration and deploys all defined AWS resources (Lambda, API Gateway, S3, IAM) into LocalStack automatically without confirmation prompts.
tflocal import aws_iam_role.lambda_exec_role lambda_exec_role	Imports an existing IAM role into Terraform’s state file. Useful if the role already exists (prevents “EntityAlreadyExists” errors).
**`jar tf target/springboot-aws-lambda-api-gateway-1.0-SNAPSHOT.zip	grep StreamLambdaHandler`**

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✅ Spring Boot AWS Lambda API Gateway running successfully on LocalStack and AWS!