Using linger with Node.js

This article explains how to use linger with a Node.js application. This combination allows your app to run persistent processes and your services to restart if your app crashes or the server reboots.

To install linger under your user, log in to your server via SSH and run the following command:

[server]$ loginctl enable-linger

This step configures Node to work with systemd user units on the server.

1. Create the following directories:

   [server]$ mkdir -p ~/.config/systemd/user/

2. Create a myapp.service file in the .config/systemd/user directory:

   [server]$ nano ~/.config/systemd/user/myapp.service

3. Add the following code to this file:

   [Unit]
   Description=Systemd instance to serve Node application
   After=network.target
   
   [Service]
   WorkingDirectory=/path/to/your/app
   ExecStart=/usr/bin/node /path/to/your/app/app.js
   Environment="PATH=/usr/bin:/usr/local/bin"
   Environment=NODE_ENV=production
   ExecReload=/bin/kill -s HUP $MAINPID
   KillMode=mixed
   TimeoutStopSec=5
   PrivateTmp=true
   Restart=on-failure
   
   [Install]
   WantedBy=default.target

4. Edit the highlighted lines above as follows:
   • WorkingDirectory: The path to your website application.
   • ExecStart: The path to your node installation.
5. Enable the user unit for your Node app:

   [server]$ systemctl --user enable myapp

6. Start the user unit for your Node app:

   [server]$ systemctl --user start myapp

7. Confirm it is running:

   [server]$ systemctl --user status myapp

Your app's services will now automatically restart when the server reboots or if the application crashes.