Rest API using AWS Lamda, Serverless and Nodejs

Prerequisite

1) AWS Lamda - If you are not aware of lamda function, please visit the following link.

http://www.fullstacktechnos.com/2017/11/what-is-aws-lamda.html

2) Serverless Framework - I am using serverless to deploy my aws infrastructure. Please visit the following article to setup the serverless in your local box.
You don't need to create any project though.

http://www.fullstacktechnos.com/2017/11/create-your-first-nodejs-lamda-function.html

Setup

If you have configured serverless for aws successfully then verify the installations by typing the command in the terminal. Your version number may not match mine.

$node -v
v6.11.3
$sls -v
1.18.1
$aws --version
aws-cli/1.11.127 Python/3.6.2 Darwin/17.2.0 botocore/1.5.90
$cat ~/.aws/credentials 
[default]
aws_access_key_id=*******************
aws_secret_access_key=*****************


I have already created the sample nodejs lamda project with serverless. Please find the following  github link.


https://github.com/fullstacktechnos/serverless-lamda-test


Checkout the code.


git clone https://github.com/fullstacktechnos/serverless-lamda-test.git


handler.js : (lamda code goes here)

'use strict';

module.exports.helloWorld = (event, context, callback) => {
  const response = {
    statusCode: 200,
    headers: {
      'Access-Control-Allow-Origin': '*', // Required for CORS support to work
    },
    body: JSON.stringify({
      message: 'Go Serverless v1.0! Your function executed successfully!',
      input: event,
    }),
  };

  callback(null, response);
};


serverless.yml:


# Welcome to serverless. Read the docs
# https://serverless.com/framework/docs/

# Serverless.yml is the configuration the CLI
# uses to deploy your code to your provider of choice

# The `service` block is the name of the service
service: serverless-hello-world

# The `provider` block defines where your service will be deployed
provider:
  name: aws
  runtime: nodejs6.10

# The `functions` block defines what code to deploy
functions:
  helloWorld:
    handler: handler.helloWorld
    # The `events` block defines how to trigger the handler.helloWorld code
    events:
      - http:
          path: hello-world
          method: get
          cors: true

To define a rest endpoint we have to mention the method (get or post) and path inside events -> http.
cors: true will enable the cross.

To know more about it please visit the serverless.com (https://serverless.com/framework/docs/providers/aws/guide/events/)


If you want to push the same code to your aws environment then run the following command.


$sls deploy

Serverless: Packaging service...
Serverless: Excluding development dependencies...
Serverless: Uploading CloudFormation file to S3...
Serverless: Uploading artifacts...
Serverless: Uploading service .zip file to S3 (967 B)...
Serverless: Validating template...
Serverless: Updating Stack...
Serverless: Checking Stack update progress...
..............
Serverless: Stack update finished...
Service Information
service: serverless-hello-world
stage: dev
region: us-east-1
api keys:
  None
endpoints:
  GET - https://l2krwp3ete.execute-api.us-east-1.amazonaws.com/dev/hello-world
functions:
  helloWorld: serverless-hello-world-dev-helloWorld


- Go to the browser and enter the GET endpoint URL. Your's will be different than mine. Mine is for testing purpose. It wont be available for you.

- You can see the event object that lamda return as a response in the browser.


* For more information please visit the following link.
https://aws.amazon.com/lambda/details/
https://serverless.com/framework/docs/providers/aws/guide/quick-start/