A Simple Node App on AWS Lambda

Introduction

This is a small tutorial on how to build a simple node app from scratch and to put that up on AWS-Lambda.

Contents

I. Make a Simple Node App
II. Host the app as a function in AWS-Lambda.

A Simple Node App

1. Install Node( for Mac)

   brew install nodejs

   Install node with binary located at
   /usr/local/opt/node

2. Create Container
   Create the package folder and get inside it. Say the name is 'puppdf.'

   mkdir puppdf
cd puppdf

3. Initialise the project

   Intialization is the creation of 'package.json', a configuration (json) file for our app.

   a. Using Terminal Prompt
   Run the following and enter appropriate info on prompt

   `npm init`
   

   b. Manually Create
   Create a package.json file and enter the fields and keys. For template one can pick from below
   

{
  "name": "puppdf",
  "version": "1.0.0",
  "description": "convert html to pdf using puppeteer",
  "main": "src/pdf.js",
  "directories": {
    "src": "src"
  },
  "files": [
    "src"
  ],
  "scripts": {
    "start:dev": "node src/pdf.js",
    "start:build": "npm install && npm run-script build",
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "repository": {
    "type": "git",
    "url": "git+https://github.com/nilinswap/puppdf.git"
  },
  "engines": {
    "node": ">=10.16.3"
  },
  "keywords": [
    "pdf",
    "node",
    "puppeteer"
  ],
  "author": "Swapnil Sharma <[e-mail]>",
  "license": "ISC",
  "bugs": {
    "url": "https://github.com/nilinswap/puppdf/issues"
  },
  "homepage": "https://github.com/nilinswap/puppdf#readme",
  "dependencies": {
    "puppeteer": "^1.20.0"
  }
}

1. create a folder src and add a file named pdf.rs in it. This file takes an url and converts related html to pdf

//pdf.rs

const puppeteer = require('puppeteer');
(async () => {
    const browser = await puppeteer.launch()
    const page = await browser.newPage()
    await page.goto('https://www.medium.com')
    await page.pdf({path: 'medium.pdf', format: 'A4'})
    await browser.close()
})()

At this point, The app is in running state. Let's try to put it up in AWS-Lambda.

Put it up on Lambda

1. Install serverless framework

   npm install -g serverless

2. Create an AWS Account.

3. Add a user with programmatic access permission.
   follow this tutorial for it.

using serverless

1. Configure serverless CLI with your AWS credentials. This is necessary for deployment.

   serverless config credentials --provider aws --key xxxxxxxxxxxxxx --secret xxxxxxxxxxxxxx

2. create essentials for serverless serverless.yml and handler.js
   If there is absence of a template file, run serverless create --template aws-nodejs --path test
   to generate default files.

3. After reviewing serverless.yml, run serverless deploy. Before running this make sure that node_modules/ folder is part of the package.
   If the package is too big one might need to use S3 for loading zip.

using AWS Console

1. create index.js and write handler functions there.
   add package.json (like mentioned above) and have 'node_modules/' prepared (by running npm install)
   and zip up the index.js and node_modules using
   
   zip -r index.zip index.js node_modules
   

   and upload this zip in AWS-lambda create function set.
   

   exports.helloWorld = function (event, context, callback) {
   let requestBody = JSON.parse(event.body);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);};
   

   index.js

2. Register a Test Event in Test action and test.

3. Create a Trigger(I used api-endpoint for trigger.) and use your lambda function in production.

This is mostly written for me to refer it in future.