How to Install Docker on Ubuntu, Debian, and CentOS

Quick Answer: Ubuntu/Debian: curl -fsSL https://get.docker.com | sh && sudo usermod -aG docker $USER. Log out and back in. Verify: docker run hello-world. That's it.

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What Is Docker?

Docker runs applications in containers — lightweight, isolated environments that include everything the app needs (code, libraries, dependencies). Instead of installing software directly on your server (and dealing with version conflicts), you run each app in its own container.

Think of it like this:

• Without Docker: Install Nginx, then install Node.js, then install PostgreSQL — all on the same OS. They share libraries and can conflict.
• With Docker: Each runs in its own container with its own libraries. They can't interfere with each other.

┌─────────────┐ ┌─────────────┐ ┌─────────────┐
│   Nginx     │ │   Node.js   │ │  PostgreSQL  │
│  Container  │ │  Container  │ │  Container   │
└─────────────┘ └─────────────┘ └─────────────┘
              Docker Engine
─────────────────────────────────────────────────
              Linux (Ubuntu/Debian/etc.)

Method 1: Convenience Script (Fastest)

The official Docker convenience script works on all supported Linux distros:

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

This detects your distro, adds the Docker repository, and installs Docker Engine + Docker Compose.

Post-Install: Run Docker Without sudo

By default, Docker requires sudo. Add your user to the docker group:

sudo usermod -aG docker $USER

Log out and log back in (or run newgrp docker) for the group change to take effect.

Verify Installation

docker --version
# Docker version 27.x.x, build ...

docker compose version
# Docker Compose version v2.x.x

docker run hello-world
# Should print "Hello from Docker!"

If docker run hello-world works, Docker is installed and running correctly.

Method 2: Official Repository (Ubuntu/Debian)

For more control over the installation:

Remove Old Versions

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

Add Docker's Official Repository

# Install prerequisites
sudo apt update
sudo apt install ca-certificates curl gnupg -y

# Add Docker's GPG key
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

For Debian, replace ubuntu with debian in the two URLs above.

Install

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

Post-Install

sudo usermod -aG docker $USER
# Log out and back in

# Enable Docker to start on boot
sudo systemctl enable docker

# Verify
docker run hello-world

Method 3: CentOS/RHEL/Fedora

Remove Old Versions

sudo dnf remove docker docker-client docker-client-latest docker-common docker-latest docker-latest-logrotate docker-logrotate docker-engine 2>/dev/null

Add Docker Repository

sudo dnf install dnf-plugins-core -y
sudo dnf config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo

For Fedora, replace centos with fedora in the URL.

Install

sudo dnf install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin -y

Start and Enable

sudo systemctl start docker
sudo systemctl enable docker
sudo usermod -aG docker $USER
# Log out and back in

docker run hello-world

Docker Compose

Docker Compose comes bundled with Docker Engine (as docker compose, no hyphen). No separate installation needed.

# Verify
docker compose version

# Basic usage
docker compose up -d        # Start services in background
docker compose down          # Stop and remove
docker compose logs -f       # Follow logs
docker compose pull          # Update images
docker compose ps            # Show running containers

Your First Compose File

Create compose.yml:

services:
  web:
    image: nginx:alpine
    ports:
      - "8080:80"
    restart: unless-stopped

docker compose up -d
# Visit http://your-server:8080 — you'll see the Nginx welcome page

Full reference: Docker Compose Examples

Essential Docker Commands

# Run a container
docker run -d --name myapp -p 8080:80 nginx

# List running containers
docker ps

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

# Stop a container
docker stop myapp

# Start a stopped container
docker start myapp

# Remove a container
docker rm myapp

# View logs
docker logs myapp
docker logs -f myapp        # Follow (tail)

# Shell into a running container
docker exec -it myapp /bin/sh

# List images
docker images

# Remove an image
docker rmi nginx

# Clean up unused resources
docker system prune          # Remove stopped containers, unused networks
docker system prune -a       # Also remove unused images (re-downloads needed)

Full reference: Docker Cheat Sheet

Configure Docker

Log Rotation (Important!)

Docker logs can fill your disk. Set up automatic rotation:

sudo nano /etc/docker/daemon.json

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

sudo systemctl restart docker

This limits each container's log to 10MB with 3 rotated files (30MB max per container).

Change Docker Storage Location

By default Docker stores data in /var/lib/docker. To move it (e.g., to a larger disk):

sudo systemctl stop docker
sudo nano /etc/docker/daemon.json

{
  "data-root": "/mnt/docker-data"
}

sudo rsync -a /var/lib/docker/ /mnt/docker-data/
sudo systemctl start docker

Uninstall Docker

# Ubuntu/Debian
sudo apt purge docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin -y
sudo rm -rf /var/lib/docker /var/lib/containerd

# CentOS/Fedora
sudo dnf remove docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin -y
sudo rm -rf /var/lib/docker /var/lib/containerd

Troubleshooting

# Check if Docker is running
sudo systemctl status docker

# Start Docker if it's stopped
sudo systemctl start docker

# Check Docker info
docker info

# Test network connectivity inside a container
docker run --rm alpine ping -c 3 google.com

What's Next?

Now that Docker is installed:

• Docker Cheat Sheet — every command you need
• Docker Compose Examples — ready-to-use service templates
• Complete Docker Guide — deep dive
• Complete Self-Hosting Guide — deploy full server
• Nginx Reverse Proxy — put services behind HTTPS
• Server Hardening — secure your server