Docker on Hetzner: A Complete Beginner's Guide

Why Docker on a VPS?

Docker lets you package applications with all their dependencies into portable containers. On a VPS, this means:

• Consistent environments — no "works on my machine" problems
• Easy deployments — docker compose up and you're live
• Isolation — each app runs in its own container, can't interfere with others
• Reproducibility — your entire stack is defined in code

Installing Docker on Ubuntu 24.04

The official Docker installation for Ubuntu:

# Remove old versions
sudo apt remove docker docker-engine docker.io containerd runc

# Add Docker's official GPG key
sudo apt update
sudo apt install ca-certificates curl
sudo install -m 0755 -d /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg
sudo chmod a+r /etc/apt/keyrings/docker.gpg

# Add the repository
echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu \
  $(. /etc/os-release && echo "$VERSION_CODENAME") stable" | \
  sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

# Install Docker
sudo apt update
sudo apt install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin -y

Post-Installation

Add your user to the docker group so you don't need sudo:

sudo usermod -aG docker $USER
newgrp docker

Verify:

docker run hello-world

Essential Docker Commands

# List running containers
docker ps

# List all containers (including stopped)
docker ps -a

# View container logs
docker logs <container_name>

# Execute a command in a running container
docker exec -it <container_name> bash

# Stop/start/restart a container
docker stop <name>
docker start <name>
docker restart <name>

# Remove unused images/containers/volumes
docker system prune -a

Docker Compose: The Real Power

For anything beyond a single container, Docker Compose is how you define multi-service applications.

Example docker-compose.yml for a Next.js app with PostgreSQL:

version: "3.8"
services:
  app:
    build: .
    ports:
      - "3000:3000"
    environment:
      DATABASE_URL: postgres://user:pass@db:5432/myapp
    depends_on:
      - db

  db:
    image: postgres:16
    volumes:
      - pgdata:/var/lib/postgresql/data
    environment:
      POSTGRES_USER: user
      POSTGRES_PASSWORD: pass
      POSTGRES_DB: myapp

volumes:
  pgdata:

Deploy with:

docker compose up -d

Resource Management on Hetzner

On a CPX42 (8 vCPU, 16GB RAM), you can comfortably run:

• 5-10 web applications
• 2-3 databases
• Coolify management platform
• Mailcow email stack (if configured correctly)

Monitor resource usage:

docker stats

Best Practices

1. Always use named volumes for persistent data

2. Never store secrets in Dockerfiles — use environment variables or Docker secrets

3. Pin image versions — use postgres:16 not postgres:latest

4. Use multi-stage builds to keep images small

5. Set resource limits with deploy.resources.limits

Next Steps

Docker is the foundation for everything else — Coolify uses it, Mailcow uses it, and most modern applications ship with Dockerfiles.

Our complete VPS guide covers Docker in the context of a full production stack, including networking, volume management, and integration with Coolify and Mailcow.