Getting Started With Serverless Framework

A serverless framework is an open-source tool used for developing and deploying serverless applications. It is a vendor-neutral framework as it can be used with AWS, Azure, or GCP. It provides a fully serverless application lifecycle management.

Install the serverless CLI

Install the Serverless CLI using npm as shown below. This will install serverless CLI globally.

npm install -g serverless

Configure AWS credentials

Configure the serverless with AWS credentials using the below command. The provider is AWS and we need to set the access key and secret key.

serverless config credential --provider aws --key fakeaccesskey --secret fakesecretkey

Install serverless-localstack plugin

This plugin is required to run serverless to support running against the local stack. This plugin allows Serverless applications to be deployed and tested on your local machine. Any requests to AWS to be redirected to a running LocalStack instance.

npm install --save-dev serverless-localstack

Create a new serverless project

Serverless provides various templates which we can use to get a headstart. To see a list of available templates run the below command.

npm serverless create --help

Let us select the aws-nodejs as shown below

serverless create --template aws-nodejs

Once the project is created successfully, you will see the below code.

1. handler.js

"use strict";

module.exports.hello = async (event) => {
  return {
    statusCode: 200,
    body: JSON.stringify(
      {
        message: "Go Serverless v1.0! Your function executed successfully!",
        input: event,
      },
      null,
      2
    ),
  };

  // Use this code if you don't use the http event with the LAMBDA-PROXY integration
  // return { message: 'Go Serverless v1.0! Your function executed successfully!', event };
};

1. serverless.yml

service: localstack-serverless
frameworkVersion: "2"

provider:
  name: aws
  runtime: nodejs12.x
  lambdaHashingVersion: 20201221

functions:
  hello:
    handler: handler.hello

Let us now update the serverless.yml file to include the LocalStack plugin as shown below.

service: localstack-serverless
plugins:
  - serverless-localstack

custom:
  localstack:
    debug: true
    stages:
      - local
      - development
    endpointFile: endpoints.json
frameworkVersion: "2"

provider:
  name: aws
  runtime: nodejs14.x
  lambdaHashingVersion: 20201221

functions:
  hello:
    handler: handler.hello

We have added the development and local stage and also we are pointing to endpoints.json which is defined as below.

endpoint.json

{
  "CloudFormation": "http://localhost:4566",
  "CloudWatch": "http://localhost:4566",
  "Lambda": "http://localhost:4566",
  "S3": "http://localhost:4566",
  "APIGateway": "http://localhost:4566",
  "Route53": "http://localhost:4566"
}

We can add the gateway events in the serverless.yml file as shown below. It has an GET endpoint with the path as hello

functions:
  hello:
    handler: handler.hello
    events:
      - http:
          path: hello
          method: get

Now let us deploy using the below command.

serverless deploy --stage local

You can see in the above screenshot, you will see we have deployed the serverless function to LocalStack which returns the endpoints as shown below

endpoints:
  http://localhost:4566/restapis/7133myfcjr/local/_user_request_

To invoke the hello function use the following URL in the Browser

http://localhost:4566/restapis/7133myfcjr/local/_user_request_/hello