Keep your node server running using PM2

The open event webapp generator is a node projects (using an express server), and a copy of it runs all the time on my personal DigitalOcean box (other than our heroku instance).

On a service like Heroku, the platform manages the task of bringing your server process up. But on, say a Linux distro on the DO box, you have to manually do

 npm run server

to be able to run the server.

While that is all good, it is a foreground shell process, which means, you will lose the node server, when you log out (or your internet connection into the ssh breaks).
So we need to be able to keep the process running in the background.

The way we do it in bash on Unix, is that we can do either of the following

 npm run server&

The “&” at the end means it will make a background fork of this task. Or if you’ve already started it without it, you can also do the following.

npm run server # starts in foreground
#Press Ctrl + Z, this pauses task and frees the shell
bg 1 # sends task no 1 to background thread.

Again, both these are hacky methods, will work only on Unix OSs, and are not really recommended for production.
For production, we need a Process Manager, for Node.js the best we can get is pm2 – purpose built process manager for node.

Install pm2 first

sudo npm install -g pm2

Using pm2, we can start any process that can be started with node. We can start the app.js script like this

pm2 start src/app.js

Also, pm2 can run npm tasks too like

pm2 start npm -- start

Pm2 has a pretty status message display window. And we can start, stop, pause, kill and/or restart any process.

 

Screenshot from 2016-08-28 01-19-29