This is a very simple demonstration of the code required to deploy a Java AWS Lambda Function and expose the function with AWS API Gateway. The infrastructure configuration and deployment is executed using HashiCorp's Terraform programmable infrastructure tool.

To get started simply create a terraform.tfvars file in terraform directory with your AWS account/IAM User details. Your IAM User must have permissions for AWS Lambda and AWS API Gateway.

The contents should follow the template below (with you replacing the info between << >>):

aws_access_key = "<< your IAM user AWS access key >>"
aws_secret_key = "<< your IAM user AWS secret key >>"
region = "<< your chosen region >>"
account_id = "<<your AWS account id>>"

From the root of the project run the build_and_deploy.sh script. This compiles the Java application into the helloworld/target directory and runs Terraform to upload and configure the Lambda function and API Gateway.

$ ./build_and_deploy.sh

After a successful run, something similar to the output below should be visible:

Outputs:

curl = curl -H 'Content-Type: application/json' -X POST -d '{"name": "Daniel"}' https://XXXXXXXXXX.execute-api.eu-west-1.amazonaws.com/beta/helloworld

To test your Lambda deployed behind the API Gateway all you need to do is copy/paste the curl command (minus the curl = part) e.g.

curl -H 'Content-Type: application/json' -X POST -d '{"name": "Daniel"}' https://XXXXXXXXXX.execute-api.eu-west-1.amazonaws.com/beta/helloworld

You can make changes to the Java application and run the build_and_deploy.sh script repeatedly to update the Lambda Function deployed into AWS.

When you are finished, don't forget to shut your infrastructure down:

$ ./destroy.sh

Please note: I'm not responsible for any costs incurred within your AWS account :-)