What is Process Manager?

Process Manager is a special program design to effectively manage server process and take benefit of server resources. It's useful to keep application online and restart on failure.

Process Manager is also useful for clustering, logging and monitoring the application. Process Managers make it possible to demonize the application so it will be running in background as a service.

Prerequisites:

In this tutorial we assume that you have following setup:

• Ubuntu server and a user with root / sudo privileges
• All the necessary package installed to run simple NodeJS App

Which Process Manager?

There are multiple Process Manager available, as listed below but in this tutorial we will be focusing on PM2.

• PM2
• StrongLoop PM
• Forever

Why PM2?

Following are the complete features set of PM2

Install Process Manager:

Use npm to install the pm2 globally so it will available system-wide for use

$ sudo npm i pm2 -g

Now let start our NodeJS app using pm2 start command

First change the directory to our node application directory

$ cd /opt/hello-pm2/
$ pm2 start app.js --name Hello -i 2 --watch

It will also register our app in the process list of PM2, which you can see in the output of the above command

PM2 as a service:

PM2 will take care of all the application running under it and will restart automatically if the application killed or crash, but what if the system boot or reboot? PM2 has answer for this, PM2 provide an easy way to start PM2 as a system service in systemd.

The startup command generate and configure a PM2 startup script.

$ pm2 startup

Now to setup the startup script copy/paste the last line from the output or earlier command,

[PM2] Init System found: systemd
meswapnilwagh
[PM2] To setup the Startup Script, copy/paste the following command:
sudo env PATH=$PATH:/usr/bin /usr/lib/node_modules/pm2/bin/pm2 startup systemd -u meswapnilwagh --hp /home/meswapnilwagh

Run the command to setup PM2 to start on boot/reboot

sudo env PATH=$PATH:/usr/bin /usr/lib/node_modules/pm2/bin/pm2 startup systemd -u meswapnilwagh --hp /home/meswapnilwagh

Basic PM2 Commands:

Just like all other command line utility, PM2 also comes with bundle of subcommands which are helpful to manage application running under PM2

Start Application in cluster

To start application in cluster mode you can use -i flag and specify the number of instances you want to run you can also use --name flag to name your process.

sudo pm2 start /opt/hello-pm2/app.js --name Hello -i 4

Stop Application

sudo pm2 stop Hello

Restart Application

sudo pm2 restart Hello

List Applications

sudo pm2 list

Monitor Application Process

sudo pm2 monit

For more usage of PM2 please refer PM2 quick start.

NGINX As Reverse Proxy :

Till now we configure PM2 and running our node app in cluster seems all good, but are you still ready for production? How can you get rid of that port in your URL? Answer to all your question is Nginx (Engine-X).

What is NGINX?

Officially, Nginx is a web server which can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.

Best practice to deploy NodeJS application in production, is by using Nginx as reverse proxy to route the web client's requests to appropriate node process.

Install NGINX

Use following command to install Nginx on Ubuntu

$ sudo apt-get update
$ sudo apt-get install nginx

Configure NGINX

Open the nginx default site config file:

$ sudo nano /etc/nginx/sites-available/default

Now add below configuration in the file (You can take backup of original file for safer side)

server {
  listen       80;
  server_name  mycooldomain.com;

  location / {
    proxy_pass http://localhost:4000;
    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection 'upgrade';
    proxy_set_header Host $host;
    proxy_cache_bypass $http_upgrade;
  }
}

As you can see the nginx listening on http://mycooldomain.com and the location / block take care of the incoming request and forwarding to NodeJS application.

Save the file and restart nginx,

$ sudo service nginx restart

Now open your browser and navigate to http://mycooldomain.com, you can see how node app is being served without using any port in URL.

Congratulations!! You had successfully deployed NodeJS app on production using PM2 and Ngnix.

Hope you find this tutorial helpful. Don't forget to share if its really help you. For any query please DM at Swapnil Wagh