api-gateway-test

This is a sample template for api-gateway-test - Below is a brief explanation of what we have generated for you:

.
├── README.MD                   <-- This instructions file
├── src                         <-- Source code for a lambda function
│   └── app.js                  <-- Lambda function code
│   └── package.json            <-- NodeJS dependencies and scripts
│   └── tests                   <-- Unit tests
│       └── unit
│           └── test-handler.js
├── template.yaml               <-- SAM template
├── swagger.yaml                <-- Swagger definition
├── buildspec.yml               <-- Build file processed by pipeline

Requirements

• AWS CLI already configured with Administrator permission
• NodeJS 10.10+ installed
• Docker installed

Setup process

Local development

Invoking function locally using a local sample payload

sam local invoke GetUsersFunction --no-event

Local invoke parameters

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/users

SAM CLI is used to emulate both Lambda and API Gateway locally and uses our template.yaml to understand how to bootstrap this environment (runtime, where the source code is, etc.) - The following excerpt is what the CLI will read in order to initialize an API generate resources/methods from the swagger file.

...
  ServerlessRestAPI:
    Type: AWS::Serverless::Api
    Properties:
      StageName: dev
      EndpointConfiguration: REGIONAL
      DefinitionBody:
        'Fn::Transform':
          Name: 'AWS::Include'
          Parameters:
            Location: './swagger.yaml'

The swagger file also contains where Lambda invocations will be called on each method/resource (GetUsersFunction maps to the function created in our template):

...
paths:
  /users:
    get:
      description: Gets full list of users
      produces:
        - application/json
      responses:
        '200':
          description: The request was successful.
          schema:
            type: array
            items:
              $ref: '#/definitions/User'
      x-amazon-apigateway-integration:
        uri: 
            Fn::Sub: arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${GetUsersFunction.Arn}/invocations
        passthroughBehavior: when_no_match
        httpMethod: POST
        type: aws_proxy
        ...

Packaging and deployment

AWS Lambda NodeJS runtime requires a flat folder with all dependencies including the application. SAM will use CodeUri property to know where to look up for both application and dependencies:

...
    GetUsersFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: src/
      ...

Firstly, we need a S3 bucket where we can upload our Lambda functions packaged as ZIP before we deploy anything - If you don't have a S3 bucket to store code artifacts then this is a good time to create one:

aws s3 mb s3://BUCKET_NAME

As long as the pipeline has been built correctly using the Terraform a simple git commit and push to the correct repo/branch should trigger the code being built/deployed to the API Gateway.

See Serverless Application Model (SAM) HOWTO Guide for more details in how to get started.

You can find more information and examples about filtering Lambda function logs in the SAM CLI Documentation.

Testing

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 src
npm install
npm run test

Cleanup

In order to delete our Serverless Application recently deployed you just need to delete the stack from cloud formation.

Step-through debugging

• Enable step-through debugging docs for supported runtimes

Next, you can use AWS Serverless Application Repository to deploy ready to use Apps that go beyond hello world samples and learn how authors developed their applications: AWS Serverless Application Repository main page

Appendix

Building the project

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

If your dependencies contain native modules that need to be compiled specifically for the operating system running on AWS Lambda, use this command to build inside a Lambda-like Docker container instead:

sam build --use-container

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