Migrating existing REST API Server to Serverless with AWS Lambda, MongoDB and Serverless Framework

$ npm install -g serverless

$ cd your-project-directory
$ npm install --save serverless

$ sls create --template aws-nodejs --name <custom-unique-name>

.
├── .npmignore
├── handler.js
└── serverless.yml

'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 };
};

provider:
  name: aws
  runtime: nodejs12.x
  lambdaHashingVersion: 20201221
  stage: dev
  region: us-west-1
  ...

functions:
hello:
  handler: handler.hello
  ...

resources:
Resources:
  NewResource:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: my-new-bucket
Outputs:
   NewOutput:
     Description: "Description for the output"
     Value: "Some output value"

service: <autogenerated> # Service name (must be unique for your account, no two services can share the same name)

frameworkVersion: "2" # Recommended to pin it to a working version so updates won't break your application

provider:
  name: aws # Name of the cloud provider
  runtime: nodejs14.x # node runtime that the deploy will work on, this is different from the nodejs version required for sls to run
  lambdaHashingVersion: 20201221 # Recommended (honestly, no idea why. Lemme know in the comments what it means)
  memorySize: 130 # Memory size required for lambda functions to run
  timeout: 10 # 10s timeout for a request to be cancelled
  stage: {opt:stage, 'dev'} # Stage to run the functions, it is used for development process to specify which ENV to run
  region: eu-west-1 # Optional override, it will be automatically set from AWS

functions:
  api: # can be any name, this will be mapped to the functions on lambda. It has to be unique
    handler: handler.api # The file.exportedFunction that the functions will be use when the event is created
    events:
      - http: ANY / # RegExps all the HTTP Routes GET|POST|PUT|PATCH|DELETE|OPTIONS, etc.
      - http: ANY /{proxy+} # If your routes use queries and parameters

npm install aws-lambda-fastify

const awsLambdaFastify = require('aws-lambda-fastify');
const app = require('./app');

const proxy = awsLambdaFastify(app);

exports.api = (event, context) => proxy(event, context);

const fastify = require('fastify');
const cors = require('fastify-cors');

const mongoose = require('mongoose');
require('dotenv').config();

const controllers = require('./controllers');

const MONGO_URI = process.env.MONGO_URI || 'mongodb://localhost:27017/movie';
const PORT = process.env.PORT || 3000;

// Connect to the db
mongoose
  .connect(MONGO_URI, {
    useCreateIndex: true,
    useFindAndModify: false,
    useNewUrlParser: true,
    useUnifiedTopology: true,
  })
  .then((connection) => {
    console.log(`Database connected ::: ${connection.connection.host}`);
  })
  .catch((err) => {
    console.error(`Error ::: ${err.message}`);
    process.exit();
  });

// Initialize app
const app = fastify();

// CORS
app.register(cors, {
  origin: '*',
});

// Routes
app.get('/', controllers.getAll);
app.post('/create', controllers.create);
app.get('/:id', controllers.getOne);
app.put('/:id/update', controllers.updateOne);
app.delete('/:id/delete', controllers.deleteOne);

// Run as backend server if the file is called directly
if (require.main === module) {
  app.listen(PORT, (err) => {
    if (err) console.error(err);
    console.log(`server running on ${PORT}`);
  });
} else {
  // Execute as aws lambda function when required as a module
  module.exports = app;
}

// Run as backend server if the file is called directly
if (require.main === module) {
  app.listen(PORT, (err) => {
    if (err) console.error(err);
    console.log(`server running on ${PORT}`);
  });
} else {
  // Execute as aws lambda function when required as a module
  module.exports = app;
}

// const create = async (req,res) {
const create = async (event) => {
  try {
    const newMovie = await Movie.create(event.body); // Events are sent in JSON format
    return {
      statuCode: 201,
      body: JSON.stringify(
        {
          message: 'new movie created',
          newMovie,
        },
        null,
        2
      ),
    };
  } catch (err) {
    return {
      statuCode: err.code || 500,
      message: JSON.stringify(err),
    };
  }
};
...

npm install --save-dev serverless-offline

...
plugins:
  - serverless-offline

sls offline start

sls deploy