Running your Node.js application by hand is, well, not the way we roll. Imagine restarting the app every time something happens, or god forbid application crashes in the middle of the night and you find about it only in the morning - ah the horror. PM2 solves this by:
- allowing you to keep applications alive forever
- reloading applications without downtime
- facilitating common system admin tasks
To install PM2, run the following command:
sudo npm install pm2 -g
To start your process with PM2, run the following command (once in the root of your application):
pm2 start server.js
As you can see from the output shown on the image below, PM2 automatically assigns an App name (based on the filename, without the .js extension) and a PM2 id. PM2 also maintains other information, such as the PID of the process, its current status, and memory usage.
As I mentioned before, the application running under PM2 will be restarted automatically if the application crashes or is killed, but an additional step needs to be taken to get the application to launch on system startup (boot or reboot). The command to do that is the following:
pm2 startup ubuntu
The output of this command will instruct you to execute an additional command which will enable the actual startup on boot or reboot. In my case the note for the additional command was:
sudo env PATH=$PATH:/usr/local/bin pm2 startup ubuntu -u nikola
If you want to learn more about the additional PM2 options you can take a look at this post.