PM2 / systemd / Process Managers

On VMs, a process manager handles restarts, log rotation, and clustering when you are not using Docker.

4 min read Level 2/5 #fastify#pm2#systemd

What you'll learn

Install PM2 and use ecosystem.config
Write a systemd unit with Restart=always
Run as a non-root user

In containers, the orchestrator restarts crashed processes. On a plain VM you need a process manager — PM2 if you want clustering and logs out of the box, or systemd if you want zero extra dependencies.

PM2

npm i -g pm2

// ecosystem.config.cjs
module.exports = {
  apps: [
    {
      name: 'api',
      script: 'dist/index.js',
      instances: 'max',
      exec_mode: 'cluster',
      env: { NODE_ENV: 'production', PORT: 3000 },
    },
  ],
};

pm2 start ecosystem.config.cjs
pm2 startup           # generate the init script
pm2 save              # persist running list
pm2 logs api          # tail logs

instances: 'max' forks one worker per CPU and load-balances over them — Fastify on cluster mode is roughly linear with cores for stateless workloads.

systemd

If you prefer no extra runtime, a systemd unit is enough.

# /etc/systemd/system/api.service
[Unit]
Description=My Fastify API
After=network.target

[Service]
Type=simple
User=app
WorkingDirectory=/srv/api
ExecStart=/usr/bin/node dist/index.js
Restart=always
RestartSec=5
Environment=NODE_ENV=production
Environment=PORT=3000

[Install]
WantedBy=multi-user.target

sudo systemctl daemon-reload
sudo systemctl enable --now api
journalctl -u api -f

Run as a non-root user (User=app) so a code exploit can’t reach the rest of the box.

Debugging →