How to Install Docker on Your VPS

Docker lets you run applications in isolated containers, making deployment consistent and reproducible. This guide covers installation on Ubuntu/Debian.

Remove Old Docker Versions

sudo apt remove docker docker-engine docker.io containerd runc 2>/dev/null

Install Docker Engine

Add the Docker Repository

sudo apt update
sudo apt install ca-certificates curl gnupg -y
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
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

Verify Installation

sudo docker run hello-world

Run Docker Without Sudo

sudo usermod -aG docker $USER
newgrp docker
docker run hello-world

Log out and back in for the group change to take full effect.

Essential Docker Commands

| Command | Description | |---|---| | docker pull nginx | Download an image | | docker run -d -p 80:80 nginx | Run a container in the background | | docker ps | List running containers | | docker ps -a | List all containers | | docker stop CONTAINER_ID | Stop a container | | docker rm CONTAINER_ID | Remove a container | | docker logs CONTAINER_ID | View container logs | | docker exec -it CONTAINER_ID bash | Open a shell inside a container | | docker images | List downloaded images | | docker system prune -a | Remove all unused data |

Docker Compose

Docker Compose lets you define multi-container applications in a YAML file.

Nginx Example

Create a project directory and a docker-compose.yml:

mkdir ~/nginx-app && cd ~/nginx-app
nano docker-compose.yml

services:
  web:
    image: nginx:latest
    ports:
      - "80:80"
    volumes:
      - ./html:/usr/share/nginx/html
    restart: unless-stopped

mkdir html
echo "<h1>Hello from Docker!</h1>" > html/index.html
docker compose up -d

WordPress with MySQL Example

services:
  db:
    image: mysql:8.0
    volumes:
      - db_data:/var/lib/mysql
    environment:
      MYSQL_ROOT_PASSWORD: rootpassword
      MYSQL_DATABASE: wordpress
      MYSQL_USER: wpuser
      MYSQL_PASSWORD: wppassword
    restart: unless-stopped

  wordpress:
    image: wordpress:latest
    depends_on:
      - db
    ports:
      - "80:80"
    environment:
      WORDPRESS_DB_HOST: db:3306
      WORDPRESS_DB_NAME: wordpress
      WORDPRESS_DB_USER: wpuser
      WORDPRESS_DB_PASSWORD: wppassword
    volumes:
      - wp_data:/var/www/html
    restart: unless-stopped

volumes:
  db_data:
  wp_data:

Start with docker compose up -d and visit your VPS IP in a browser.

Docker Security Best Practices

Run as non-root inside containers — use USER directive in Dockerfiles

Set resource limits to prevent containers from consuming all resources:

deploy:
  resources:
    limits:
      cpus: "1.0"
      memory: 512M

Use read-only filesystems where possible: read_only: true
Create custom networks instead of using the default bridge:
```
networks:
  frontend:
  backend:
```
Enable Docker Content Trust: export DOCKER_CONTENT_TRUST=1
Keep images updated: docker compose pull && docker compose up -d

Logging Configuration

Prevent logs from filling your disk by adding to /etc/docker/daemon.json:

{
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "10m",
    "max-file": "3"
  }
}

Restart Docker:

sudo systemctl restart docker

Useful Compose Commands

| Command | Description | |---|---| | docker compose up -d | Start all services in background | | docker compose down | Stop and remove all services | | docker compose logs -f | Follow logs for all services | | docker compose pull | Pull latest images | | docker compose restart | Restart all services |