Complete Docker Installation on Ubuntu Server

# Complete Docker Installation on Ubuntu Server

Introduction

Docker is a containerization platform that enables developers to package applications with their dependencies into standardized units. This tutorial covers Docker installation on Ubuntu Server, post-installation configuration, and verification.

Learning Objectives

By the end of this tutorial, you will be able to:

• Install Docker Engine on Ubuntu Server
• Configure Docker post-installation
• Manage Docker as a non-root user
• Verify Docker installation
• Install Docker Compose
• Uninstall Docker if needed

Technical Background

Docker Architecture

Client --> Docker Daemon --> Containers
    |           |
    |           Images Registry
    |
    CLI/REST API

Docker Components

| Component | Description | |-----------|-------------| | Docker Daemon | Background service managing containers | | Docker CLI | Command-line interface | | Docker Image | Read-only template for containers | | Docker Container | Runnable instance of an image | | Docker Registry | Storage for images (Docker Hub, ECR, etc.) | | Docker Compose | Multi-container application tool |

Prerequisites

• Ubuntu Server 22.04 LTS
• Root or sudo access
• 64-bit architecture
• Internet access

Hardware and Software Requirements

| Component | Requirement | |-----------|-------------| | OS | Ubuntu 22.04 LTS | | RAM | 2 GB minimum | | Disk | 20 GB minimum | | CPU | 1 vCPU minimum |

Step-by-Step Implementation

Phase 1: Install Docker Using Repository

# Update package index
sudo apt-get update

# Install prerequisites
sudo apt-get install -y \
    ca-certificates \
    curl \
    gnupg \
    lsb-release

# Add Docker's official GPG key
sudo mkdir -p /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg

# Set up repository
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

# Install Docker Engine
sudo apt-get update
sudo apt-get install -y docker-ce docker-ce-cli containerd.io docker-compose-plugin docker-ce-rootless-extras

# Verify installation
sudo docker --version

Phase 2: Post-Installation Configuration

#### Manage Docker as Non-Root User

# Create docker group
sudo groupadd docker

# Add current user to docker group
sudo usermod -aG docker $USER

# Apply group changes
newgrp docker

# Verify (no sudo needed)
docker run hello-world

#### Configure Docker to Start on Boot

sudo systemctl enable docker.service
sudo systemctl enable containerd.service

#### Configure Docker Daemon

# Create daemon configuration
sudo tee /etc/docker/daemon.json << 'EOF'
{
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "10m",
    "max-file": "3"
  },
  "storage-driver": "overlay2"
}
EOF

# Restart Docker
sudo systemctl restart docker

Phase 3: Verify Installation

# Run hello-world container
docker run hello-world

# Check Docker info
docker info

# Check Docker version
docker version

# List running containers
docker ps

# List all containers
docker ps -a

# List images
docker images

Phase 4: Install Docker Compose (Standalone)

# Download Docker Compose
sudo curl -L "https://github.com/docker/compose/releases/download/v2.24.0/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose

# Make executable
sudo chmod +x /usr/local/bin/docker-compose

# Create symlink
sudo ln -s /usr/local/bin/docker-compose /usr/bin/docker-compose

# Verify
docker compose version

Phase 5: Basic Docker Operations

#### Run a Container

# Run Nginx container
docker run -d -p 80:80 --name my-nginx nginx:latest

# View running container
docker ps

# Stop container
docker stop my-nginx

# Remove container
docker rm my-nginx

#### Build a Custom Image

# Dockerfile
FROM nginx:alpine
COPY index.html /usr/share/nginx/html/index.html
EXPOSE 80
CMD ["nginx", "-g", "daemon off;"]

# Build image
docker build -t my-nginx:latest .

# Run image
docker run -d -p 8080:80 --name my-nginx-custom my-nginx:latest

#### Manage Images

# List images
docker images

# Remove image
docker rmi my-nginx:latest

# Pull image
docker pull nginx:latest

# Tag image
docker tag my-nginx:latest myregistry.com/my-nginx:latest

# Push image
docker push myregistry.com/my-nginx:latest

Phase 6: Docker Networking

# List networks
docker network ls

# Create custom network
docker network create my-network

# Run container on network
docker run -d --name my-container --network my-network nginx:latest

# Connect running container to network
docker network connect my-network my-container

Phase 7: Docker Volumes

# Create volume
docker volume create my-data

# Run container with volume
docker run -d -v my-data:/app/data --name my-app nginx:latest

# List volumes
docker volume ls

# Inspect volume
docker volume inspect my-data

# Remove volume
docker volume rm my-data

Phase 7: Docker Compose Example

# docker-compose.yml
version: '3.8'
services:
  web:
    image: nginx:latest
    ports:
      - "80:80"
    volumes:
      - ./html:/usr/share/nginx/html
    networks:
      - app-network
  db:
    image: postgres:15
    environment:
      POSTGRES_PASSWORD: example
    volumes:
      - db-data:/var/lib/postgresql/data
    networks:
      - app-network
networks:
  app-network:
volumes:
  db-data:

# Start services
docker compose up -d

# Stop services
docker compose down

# View logs
docker compose logs -f

# Scale service
docker compose up -d --scale web=3

Phase 8: Uninstall Docker

# Remove packages
sudo apt-get purge -y docker-ce docker-ce-cli containerd.io docker-compose-plugin

# Remove dependencies
sudo apt-get autoremove -y

# Remove images and data
sudo rm -rf /var/lib/docker
sudo rm -rf /var/lib/containerd

Expected Output

• Docker Engine installed and running
• Docker Compose installed
• Non-root user can run Docker commands
• Containers and images manageable
• Docker networks and volumes functional

Verification Procedures

| Check | Command | Expected Result | |-------|---------|-----------------| | Docker version | `docker --version` | Version displayed | | Docker info | `docker info` | Server details shown | | Hello world | `docker run hello-world` | Success message | | Docker Compose | `docker compose version` | Version displayed |

Troubleshooting Scenarios

| Issue | Diagnosis | Resolution | |-------|-----------|------------| | Permission denied | User not in docker group | Add user to docker group; newgrp | | Docker daemon not running | Service not started | `sudo systemctl start docker` | | Cannot pull image | Network or auth issue | Check network; login to registry | | Container exits immediately | Application error | Check container logs |

Best Practices

• **Use official images:** Start from verified base images
• **Pin image versions:** Use specific tags, not `latest`
• **Multi-stage builds:** Reduce image size
• **Non-root user:** Run containers as non-root
• **Resource limits:** Set memory and CPU limits
• **Health checks:** Add HEALTHCHECK to Dockerfile
• **Use volumes:** Don't store data in container layers

Security Considerations

• **Run as non-root:** Avoid root user in containers
• **Image scanning:** Scan images for vulnerabilities
• **Content trust:** Enable Docker Content Trust
• **Secrets management:** Use Docker Secrets or external secret manager
• **Network isolation:** Use custom networks to isolate containers
• **Read-only root filesystem:** Where possible

Conclusion

Docker installation on Ubuntu Server is straightforward using the official repository. With proper post-installation configuration, Docker Compose, and security best practices, you can run containerized applications reliably and securely.

References

• Docker Documentation: https://docs.docker.com/
• Docker Engine Install: https://docs.docker.com/engine/install/ubuntu/
• Docker Compose: https://docs.docker.com/compose/
• Docker Security: https://docs.docker.com/engine/security/