Docker on a VPS: installation and the first container

Docker runs applications in containers: no manual installation of dependencies and easy updates. Here is the installation on Debian or Ubuntu and an example with Docker Compose.

Installation

Docker's official script installs Docker together with Docker Compose:

curl -fsSL https://get.docker.com | sh

Check that it works:

docker run hello-world

Your first application with Docker Compose

An example: Uptime Kuma, a monitoring tool that tells you when your website or server stops working.

mkdir -p /opt/uptime-kuma && cd /opt/uptime-kuma
nano compose.yaml

Paste into the file:

services:
  uptime-kuma:
    image: louislam/uptime-kuma:1
    restart: unless-stopped
    ports:
      - "3001:3001"
    volumes:
      - ./data:/app/data

Start it:

docker compose up -d

The application is at http://IP_ADDRESS:3001. If you restrict traffic in the Firewall tab, open port 3001 there.

Useful commands

• docker ps: running containers.
• docker compose logs -f: the application's logs live.
• docker compose pull && docker compose up -d: update to a new version.
• docker system df and docker system prune: how much space images take and cleaning up unused ones.

Docker and the system firewall

Docker opens published ports past the ufw rules in the system. The rules in the panel's Firewall tab work in front of the server, so they protect Docker's ports too.

Keep application data in volumes (like ./data in the example) and make backups before updates.