How to Deploy Docker Containers on a VPS: A Beginner-Friendly Guide

# Remove old Docker versions if any
$ apt remove docker docker-engine docker.io containerd runc -y

# Install dependencies
$ apt update
$ apt install ca-certificates curl gnupg -y

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

# Add Docker 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" \
  | tee /etc/apt/sources.list.d/docker.list > /dev/null

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

$ docker --version
# Docker version 26.x.x

# Run the hello-world test container
$ docker run hello-world

# Add your user to the docker group (no sudo needed)
$ usermod -aG docker $USER
$ newgrp docker

# Verify — should run without sudo
$ docker ps

# Pull the official Nginx image from Docker Hub
$ docker pull nginx

# Run it — map port 8080 on the host to port 80 inside the container
$ docker run -d \
  --name my-nginx \
  -p 8080:80 \
  nginx

# Check it's running
$ docker ps

$ docker stop my-nginx      # Stop the container
$ docker start my-nginx     # Start it again
$ docker restart my-nginx   # Restart
$ docker rm my-nginx        # Remove container (must be stopped)
$ docker logs my-nginx      # View container logs
$ docker exec -it my-nginx bash  # Open a shell inside the container

# -p HOST_PORT:CONTAINER_PORT
$ docker run -p 3000:3000 my-node-app

# Bind to a specific IP (more secure — only localhost can reach it)
$ docker run -p 127.0.0.1:3000:3000 my-node-app

# Mount a host directory into the container
# -v /host/path:/container/path
$ docker run -v /var/www/html:/usr/share/nginx/html nginx

# Named volume (Docker manages the storage location)
$ docker run -v my-db-data:/var/lib/mysql mysql

# Pass configuration to containers without hardcoding secrets
$ docker run -d \
  -e DB_HOST=localhost \
  -e DB_PASSWORD=secret123 \
  -e NODE_ENV=production \
  my-app

# Docker Compose V2 is included with the Docker installation
# If you installed Docker via the official repo, it's already there:
$ docker compose version
# Docker Compose version v2.x.x

# If not installed, add the plugin manually:
$ apt install docker-compose-plugin -y

services:

  app:
    image: node:20-alpine
    container_name: my-app
    working_dir: /app
    volumes:
      - ./app:/app          # Mount local code into container
    ports:
      - "127.0.0.1:3000:3000"  # Expose only to localhost
    environment:
      - NODE_ENV=production
      - DB_HOST=postgres      # Service name = hostname
      - DB_PASSWORD=${DB_PASSWORD}  # Read from .env file
      - REDIS_HOST=redis
    command: node server.js
    depends_on:
      - postgres
      - redis
    restart: unless-stopped
    networks:
      - app-network

  postgres:
    image: postgres:16-alpine
    container_name: my-postgres
    environment:
      - POSTGRES_DB=myapp
      - POSTGRES_PASSWORD=${DB_PASSWORD}
    volumes:
      - postgres-data:/var/lib/postgresql/data  # Persist DB data
    restart: unless-stopped
    networks:
      - app-network

  redis:
    image: redis:7-alpine
    container_name: my-redis
    restart: unless-stopped
    networks:
      - app-network

volumes:
  postgres-data:   # Named volume — data survives container restarts

networks:
  app-network:
    driver: bridge

DB_PASSWORD=your-super-secret-password

# Start all services in the background
$ docker compose up -d

# View running services
$ docker compose ps

# View logs (all services, or one)
$ docker compose logs -f
$ docker compose logs -f app

# Stop all services
$ docker compose down

# Stop and remove volumes (⚠️ deletes DB data)
$ docker compose down -v

# Enable Docker daemon to start on system boot
$ systemctl enable docker

# Verify
$ systemctl is-enabled docker
# enabled