Systemd

The (generally) best way to run your apps 24/7 in the background on nest is through the use of systemd. It runs as PID 1 and is the first thing that starts in any nest container. For more information check out https://wiki.archlinux.org/title/Systemd (one of the best systemd docs in my opinion).

Tutorial

We are going to run your project as a systemd service, which are usually located in /etc/systemd/system/<name>.service. To create/edit this, file you can either use nano /etc/systemd/system/<name>.service or systemctl edit --full --force <name>.service. For this guide we will use the latter. If you use nano, you will also need to run systemctl daemon-reload after.

1. Find out how you are running your project exactly. If you are running with node, run which node and note down the full path you get (for example /usr/local/bin/node). For anything else it's the same, just run which python/bun/etc.
2. Create a new systemctl service with systemctl edit --full --force <name>.service, make sure name is unique and represents your project (for example: "cool-slack-bot" is good, python is bad). Example: systemctl edit --full --force cool-slack-bot.service
3. Paste this file, and edit it to match your project:

[Unit]
Description=Cool Slack Bot
Wants=network-online.target
After=network-online.target

[Service]
# If you are not using node, replace /usr/local/bin/node
# Also make sure to replace <project>, and index.js if necessary
ExecStart=/usr/local/bin/node /root/<project>/index.js
# Make sure to replace <project>
WorkingDirectory=/root/<project>
Restart=always
RestartSec=5
# Uncomment this if you have a .env file, change the path if needed:
# EnvironmentFile=/root/<project>/.env

[Install]
WantedBy=multi-user.target

1. Enable and start your project using systemctl enable <name>.service --now, then check if it's running with systemctl status <name>.service.
2. If you need to view the latest logs for the service, use journalctl -eu <name>.