What is Docker Compose on VPS?
Run Multi-Container Apps with Ease

What is Docker Compose?

Docker Compose is a tool for defining and running multi-container Docker applications. Instead of typing multiple lengthy docker run commands for each container, you write a single docker-compose.yml file and start everything with one command: docker compose up.

For example, a typical web application consists of three parts: a web server, an application server, and a database. Docker Compose lets all three services work together without manually configuring the network for each one.

Docker vs Docker Compose

Beginners often confuse the two. Here's a clear comparison:

Installing Docker + Compose on Ubuntu VPS

For VPS running Ubuntu 22.04 or 24.04, follow these steps:

Step 1: Update packages and install dependencies

sudo apt update && sudo apt upgrade -y
sudo apt install -y ca-certificates curl gnupg lsb-release

Step 2: Add Docker GPG key and repository

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

Step 3: Install Docker Engine + Compose plugin

sudo apt update
sudo apt install -y docker-ce docker-ce-cli containerd.io \
  docker-buildx-plugin docker-compose-plugin

Step 4: Add user to docker group

sudo usermod -aG docker $USER
newgrp docker

Verify installation

docker --version
docker compose version

docker-compose.yml File Structure

The docker-compose.yml file uses YAML format with three main sections:

services:          # Define each container
  web:
    image: nginx:alpine
    ports:
      - "80:80"
    volumes:
      - ./html:/usr/share/nginx/html
    depends_on:
      - app

  app:
    build: .
    environment:
      - DB_HOST=db
    networks:
      - backend

  db:
    image: mysql:8
    environment:
      MYSQL_ROOT_PASSWORD: secret
    volumes:
      - db_data:/var/lib/mysql
    networks:
      - backend

volumes:           # Define named volumes
  db_data:

networks:          # Define custom networks
  backend:

Example: WordPress + MySQL on VPS

This is one of the most common Docker Compose use cases — running WordPress with a MySQL database:

version: '3.9'

services:
  wordpress:
    image: wordpress:latest
    ports:
      - "8080:80"
    restart: always
    environment:
      WORDPRESS_DB_HOST: db
      WORDPRESS_DB_USER: wpuser
      WORDPRESS_DB_PASSWORD: ${DB_PASSWORD}
      WORDPRESS_DB_NAME: wordpress
    volumes:
      - wp_data:/var/www/html
    depends_on:
      - db

  db:
    image: mysql:8.0
    restart: always
    environment:
      MYSQL_ROOT_PASSWORD: ${MYSQL_ROOT_PASSWORD}
      MYSQL_DATABASE: wordpress
      MYSQL_USER: wpuser
      MYSQL_PASSWORD: ${DB_PASSWORD}
    volumes:
      - db_data:/var/lib/mysql

volumes:
  wp_data:
  db_data:

Save as docker-compose.yml and run:

docker compose up -d
docker compose ps   # Check status

Common Commands

Networking and Volumes

Networking

When you run docker compose up, Docker automatically creates a default network named <foldername>_default. Every service can communicate with others using their service name as the hostname — so a service named db is reachable at hostname db from any other container in the same stack.

Volume Types

Managing Environment Variables with .env

Sensitive values like passwords should be stored in a separate .env file:

# .env
DB_PASSWORD=myS3cur3P@ss
MYSQL_ROOT_PASSWORD=r00tS3cr3t

Docker Compose automatically loads .env when it's in the same directory, and ${DB_PASSWORD} in the YAML is replaced with the actual value.

Production Tips for VPS

• Add restart: always to critical services so containers automatically restart after a VPS reboot.
• Limit resources with deploy.resources.limits to prevent any container from consuming excessive CPU or RAM.
• Use Nginx as a reverse proxy in front for SSL termination and routing.
• Add health checks with healthcheck: so Compose waits for a service to be truly ready before starting dependents.
• Back up volumes regularly — named volume data lives at /var/lib/docker/volumes/.
• Use override files — docker-compose.override.yml for dev-specific settings, keeping the base file clean for production.

Frequently Asked Questions