spring-batch-lambda

Spring Batch On Lambda with Sample Usage of SAM and Local Docker Run

#Lambda Local Testing Using Docker

Build and run

mvn clean package -DskipTests docker build -t batch-lambda-demo . docker run -d -p 9000:8080 batch-lambda-demo

Test with curl

curl -XPOST "http://localhost:9000/2015-03-31/functions/function/invocations" -d '{"key1":"value1","key2":"value2"}'

#Lambda Local Testing using SAM

Direct function invocation

sam local invoke BatchLambdaDemo -e event.json

Start local API Gateway (if you added the API event)

sam local start-api

Test via HTTP

curl -X POST http://localhost:3000/batch -d '{"key1":"value1"}'

Problem Recap Initial Issue: Spring Boot + AWS Lambda project couldn't run locally with SAM due to multiple build and packaging problems:

1. Maven Shade Plugin Configuration Error:
   • Error: 
Cannot find 'resource' in class ManifestResourceTransformer
   • Cause: Incorrect transformer configuration syntax
2. JAR Structure Incompatibility:
   • Error: 
ClassNotFoundException: com.example.batch_lambda_demo.BatchLambdaHandler
   • Cause: Spring Boot creates fat JARs with classes in 
BOOT-INF/classes/, but Lambda expects classes at root level
3. Missing Database Dependency:
   • Error: 
Failed to determine a suitable driver class
   • Cause: Spring Batch requires a database but none was configured Resolution Steps
4. Fixed Maven Build Configuration Before (broken):

org.apache.maven.plugins maven-shade-plugin ...

xml After (working): org.apache.maven.plugins maven-shade-plugin 3.4.1 false

xml 2. Added Missing Database Dependency com.h2database h2 runtime

xml 3. Proper JAR Structure

• Before: Classes in 
BOOT-INF/classes/com/example/...
• After: Classes at root level 
com/example/...
• Solution: Maven Shade plugin creates Lambda-compatible flat JAR structure Final Working Commands

Build

mvn clean package -DskipTests

Test locally

sam local invoke BatchLambdaDemo -e event.json

Result: "Batch completed with exit code: 0"

bash Key Insight: Spring Boot's default packaging isn't Lambda-compatible. Maven Shade plugin creates the correct flat JAR structure that AWS Lambda runtime can load.