Introduction

This project is set up to demonstrate the concepts of unit testing, continuous integration, continuous delivery, and continuous deployment. Furthermore, the application itself demonstrates the syntax and settings of Javascript, in particular, one written using Node.js and ES6 Javascript syntax.

The following tools are used:

• Git - for version control
• Node.js - for application code
• ESLint - for Javascript syntax and style checking
• Mocha - unit testing
• Babel - transpiling of written Javascript from ES6 to ES5 syntax
• Nodemon - auto-restart the node app every time the code changes in dev mode
• PM2 - manage node processes in deployment
• Travis CI - for continuous integration (we use both Travis CI and Circle CI just to provide an example of each)
• Circle CI - for continuous integration (we use both Travis CI and Circle CI just to provide an example of each)
• GitHub webhooks - for for continuous delivery/deployment
• Digital Ocean Droplet - deployment target hosting provider

Building the application from source code

Should you desire to build this application on your own machine. Do the following:

1. Clone the source code to your local machine using git
2. Navigate to the directory where the source code now resides
3. Type npm install to install all dependencies outlined in the package.json file
4. Run the application with npm start, test it with npm test, and see code coverage analysis with npm run test-with-coverage.
5. Enjoy!

Understanding how to set up an npm / node app

Should you desire to understand how to set up the application code in this project from scratch using npm's configuration and dependency management capabilities:

• Read the project setup instructions

Set up Digital Ocean Ubuntu Droplet to run Node.js applications

The following instructions are compiled from:

• https://www.digitalocean.com/community/tutorials/initial-server-setup-with-ubuntu-18-04

Setting up a Virtual Machine deployment environment on Digital Ocean

Assuming you have instantiated a Digital Ocean Ubuntu Droplet, first log in to remote Digital Ocean Droplet via SSH, then...

UFW - ubuntu wirewall

Enable common network apps so they gets through the firewall

sudo ufw allow http
sudo ufw allow https
sudo ufw allow OpenSSH
sudo ufw allow 'NGINX HTTP
sudo ufw allow 'NGINX HTTPS

Turn on the firewall... turning it off is disable as you'd expect

sudo ufw enable

list the status of firewall

sudo ufw status

List all apps the firewall knows about

sudo ufw app list

NODE

The following instructions are compiled from:

• https://www.digitalocean.com/community/tutorials/how-to-install-node-js-on-ubuntu-18-04

General purpose Javascript programming environment for server and client-side applications.

Install nodejs and npm using the APT package manager. First, get latest package list

sudo apt-get update

Install nodejs

sudo apt-get install nodejs

Install npm

sudo apt-get install npm

Check the version of npm

npm -v

Check the version of node:

node -v

NGINX

The following instructions are compiled from:

• https://www.digitalocean.com/community/tutorials/how-to-install-nginx-on-ubuntu-18-04

Web server and reverse proxy.

Install nginx using the APT package manager. First, get the latest package list:

sudo apt update

Then install nginx

sudo apt install nginx

Check whether nginx is running

systemctl status nginx

It should be started by default, but if it's not, do the following... to stop or restart, replace start with stop or restart, respectively

sudo systemctl start nginx

Find the IP address of the local machine

ip addr show eth0 | grep inet | awk '{ print $2; }' | sed 's/\/.*$//'

Try connecting to the nginx server from a web browser using the http protocol and the IP adress resulting from the above command.

Continuous deployment for a Node.js app on Digital Ocean

Set up a deploy account

The following instructions are taken, in part, from:

• https://hackernoon.com/continuous-deployment-for-node-js-on-digitalocean-d800e8520ffe

This account will be used for deployment, and will not have admin privileges

sudo adduser deploy

give some root-level access to this account

usermod -aG sudo deploy

Set up SSH key from Droplet to GitHub

Following instructions here:

• https://www.digitalocean.com/docs/droplets/how-to/add-ssh-keys/create-with-openssh/

Set up GitHub webhook

The following instructions are taken, in part, from:

• https://www.digitalocean.com/community/tutorials/how-to-use-node-js-and-github-webhooks-to-keep-remote-projects-in-sync

In GitHub repository settings, add webhook

• set it up as JSON sent to a URL on your Droplet on port 8080, and a secret passkey

On your Droplet...

Clone the GitHub repository into a directory in the droplet account home dir

Create a new 'webhooks' directory in the Droplet also within the droplet accoun home dir (but outside the clone dir)

Put the following into a file called 'webhook.js' in this webhooks directory

var secret = "your_webhook_secret_here"; //secret from GitHub webhook
var repo = "~/your_repo_dir_name"; //path to the clone repo on the Droplet

let http = require('http');
let crypto = require('crypto');

const exec = require('child_process').exec;

http.createServer(function (req, res) {
   req.on('data', function(chunk) {
       let sig = "sha1=" + crypto.createHmac('sha1', secret).update(chunk.toString()).digest('hex');

       if (req.headers['x-hub-signature'] == sig) {
           exec('cd ' + repo + ' && git pull');
       }
   });

   res.end();
}).listen(8080);

Allow traffic on this port

sudo ufw allow 8080/tcp

Test it out

cd ~/webhooks
node webhook.js

Check out the GitHub repo's settings for this webhook

• the Recent Deliveries section should show a log of the connection

Now make your node webhook app always run as a background process.

Add a system service:

sudo emacs /etc/systemd/system/webhook.service

Enter this into that webhook.service file:

[Unit]
Description=Github webhook
After=network.target

[Service]
Environment=NODE_PORT=8080
Type=simple
User=deploy
ExecStart=/usr/bin/node /home/deploy/webhooks/webhook.js
Restart=on-failure

[Install]
WantedBy=multi-user.target

Enable the new service so it starts when the system boots:

sudo systemctl enable webhook.service

Now start the service:

sudo systemctl start webhook

Ensure the service is started:

sudo systemctl status webhook

Note that this does not yet deploy the code, but has rather delivered it.... deployment is a small extra step to restart the deployed node app from the webhook script, using npm restart or some such thing.