Skip to main content

Run Node.js Applications

This article describes how to run a Node.js installation in userspace.

The installation in userspace can be recommended for several reasons:

  1. It gives you control over which Node.js version you use.
  2. You can use different versions for different applications.
  3. It allows you to install "global" npm packages.

Using the "Node Version Manager", hereafter called nvm, you can install and manage multiple Node.js versions.

The current version of nvm can be found at github.com/creationix/nvm.

Installation of nvm​

nvm is installed via an installation script, which can be retrieved from Github with curl:

curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/master/install.sh | bash

This will install nvm directly and export it to your .bashrc. To be able to use nvm directly via the CLI, the .bashrc must be read in again:

source .bashrc

Usage of NVM​

Show available version​

nvm ls-remote

Check installed versions​

nvm ls

Installing a version​

Install the latest LTS version

nvm install 'lts/*'

Install a specific version

nvm install 5.0

Use a specific version​

nvm alias default 'lts/*'

Use an arbitrary version in the current session​

nvm use 5.0

Run a command with a specific version​

# nvm exec [<version>] [<command>]
# Run <command> on <version>. Uses .nvmrc if available and version is omitted.
nvm exec 5.0 node --version

Configure a Node.js version for a specific project​

This can be done using a .nvmrc file:

$ cat .nvmrc
lts/*

Manage Applications with Process Manager (pm2)​

pm2 is a process manager for Node.js applications with an integrated load balancer. Among other things, this enables you to run applications permanently, reload applications without downtime and simplify common administration tasks.

You can install pm2 with the following command:

npm install pm2 -g

Usage of pm2​

Start applications​

pm2 start app.js

Start multiple instances of an application in cluster mode​

pm2 start app.js -i 4

Update pm2​

pm2 update

Process Monitoring​

pm2 list            # List all processes started with PM2
pm2 monit           # Display memory and cpu usage of each app
pm2 show [app-name] # Show all information about application

Startup/Boot management​

pm2 startup   # Detect init system, generate and configure pm2 boot on startup
pm2 save      # Save current process list
pm2 resurrect # Restore previously save processes
pm2 unstartup # Disable and remove startup system

Start Application after Reboot with Systemd​

To start pm2 as a user service when the system is restarted, a systemd unit (~/.config/systemd/user/pm2.service) can be used:

[Unit]
Description=PM2 process manager
Documentation=https://pm2.keymetrics.io/

[Service]
Type=forking
LimitNOFILE=infinity
LimitNPROC=infinity
LimitCORE=infinity

Environment=NODE_ENV=production
Environment=NODE_VERSION=14
Environment=PM2_HOME=%h/.pm2

PIDFile=%h/.pm2/%p.pid

ExecStart=%h/.nvm/nvm-exec pm2 resurrect
ExecReload=%h/.nvm/nvm-exec pm2 reload all
ExecStop=%h/.nvm/nvm-exec pm2 kill

[Install]
WantedBy=default.target

More information about how to use SystemD is available in the following support article.