Here's a basic breakdown of the folder structure for this repo:

.
├── README.md                   <-- This instructions file
├── podbooster                  <-- Source code for a lambda function
│   ├── index.js                <-- Lambda function code
│   ├── package.json            <-- NodeJS dependencies
│   └── tests                   <-- Unit tests
│       └── unit
│           └── test_handler.js
└── template.yaml               <-- SAM template

• AWS CLI already configured with Administrator permission
• NodeJS 8.10+ installed
• Docker installed

AWS Lambda requires a flat folder with the application as well as its dependencies in a node_modules folder. When you make changes to your source code or dependency manifest, run the following command to build your project local testing and deployment:

sam build --use-container

By default, this command writes built artifacts to .aws-sam/build folder.

Invoking function locally through local API Gateway

sam local start-api

If the previous command ran successfully you should now be able to hit the following local endpoint to invoke your function http://localhost:3000/podbooster

We use mocha for testing our code and it is already added in package.json under scripts, so that we can simply run the following command to run our tests:

cd podbooster
npm install
npm run test

Because differences in machine architecture, the files to be uploaded to lambda (like node_modules) must all be built in an Amazon Linux 2 Docker container so that the Lame bindings work in lambda.

1. build the docker image locally: docker build -f Dockerfile . -t scprdev/lambda-podbooster
2. run the image: docker run -v path/to/this/repo/podbooster:/working -it scprdev/lambda-podbooster:latest
3. note in the previous step that the path is to the podbooster directory in this current repo, not the repo root. We're mapping that to the '/working` directory in the docker container.
4. the previous docker run command should have created a new lambda.zip file in the repo root (check the timestamp to verify)
5. run ./publish.sh to publish that lambda.zip to AWS lambda