Installing and Configuring Docker on Linux

Restart Docker to apply the configuration:

sudo systemctl restart docker

First test with Docker

Basic test

Test your installation with the hello-world image:

docker run hello-world

Running an interactive container

Launch an interactive Ubuntu container:

docker run -it ubuntu:latest bash

Managing Docker images

Searching for images

# Search for an image on Docker Hub
docker search nginx

# Download an image
docker pull nginx:latest

# List local images
docker images

Removing images

# Remove a specific image
docker rmi nginx:latest

# Remove unused images
docker image prune

# Remove all unused images
docker image prune -a

Managing containers

Basic commands

# Run a container in the background
docker run -d --name my-nginx nginx

# List active containers
docker ps

# List all containers
docker ps -a

# Stop a container
docker stop my-nginx

# Restart a container
docker start my-nginx

# Remove a container
docker rm my-nginx

Practical example: Nginx web server

# Run Nginx with port mapping
docker run -d \
    --name web-server \
    -p 8080:80 \
    -v $(pwd)/html:/usr/share/nginx/html:ro \
    nginx:latest

# Check that the server is working
curl http://localhost:8080

Building custom images

Basic Dockerfile

Create a Dockerfile to build your own image:

# Use a base image
FROM ubuntu:20.04

# Set the maintainer
LABEL maintainer="[email protected]"

# Update and install packages
RUN apt-get update && apt-get install -y \
    nginx \
    curl \
    && rm -rf /var/lib/apt/lists/*

# Copy configuration files
COPY nginx.conf /etc/nginx/nginx.conf
COPY index.html /var/www/html/

# Expose the port
EXPOSE 80

# Set the default command
CMD ["nginx", "-g", "daemon off;"]

Building the image

# Build the image
docker build -t my-server:1.0 .

# Run a container from your image
docker run -d -p 8080:80 --name my-app my-server:1.0

Docker Compose

Installing Docker Compose

Docker Compose is now included as a plugin. Verify the installation:

docker compose version

Example docker-compose.yml

version: "3.8"

services:
  web:
    image: nginx:latest
    ports:
      - "8080:80"
    volumes:
      - ./html:/usr/share/nginx/html:ro
    restart: unless-stopped

  database:
    image: mysql:8.0
    environment:
      MYSQL_ROOT_PASSWORD: secure_password
      MYSQL_DATABASE: app_db
    volumes:
      - db_data:/var/lib/mysql
    restart: unless-stopped

volumes:
  db_data:

Using Docker Compose

# Start the services
docker compose up -d

# View the logs
docker compose logs

# Stop the services
docker compose down

# Stop and remove the volumes
docker compose down -v

Security best practices

Securing the Docker daemon

• Non-root users: Avoid running processes as root inside containers
• Official images: Favor official and verified images
• Updates: Keep Docker and your images up to date
• Limited resources: Limit container memory and CPU

Example of a secured container

docker run -d \
    --name secured-app \
    --user 1000:1000 \
    --memory="512m" \
    --cpus="0.5" \
    --read-only \
    --tmpfs /tmp \
    nginx:latest

Security scan

# Scan an image for vulnerabilities
docker scout quickview nginx:latest

Monitoring and maintenance

Resource monitoring

# Real-time statistics
docker stats

# Docker system information
docker system df

# Automatic cleanup
docker system prune

# Full cleanup (be careful!)
docker system prune -a --volumes

Logs and debugging

# View a container's logs
docker logs my-container

# Follow the logs in real time
docker logs -f my-container

# Run a command inside a container
docker exec -it my-container bash

Conclusion

Docker is now installed and configured on your Linux system. You have the basic knowledge to:

• Manage Docker images and containers
• Create your own images with a Dockerfile
• Orchestrate multi-container applications with Docker Compose
• Apply security best practices
• Monitor and maintain your Docker environment

Docker revolutionizes application deployment by offering a portable, lightweight and consistent solution across all your development and production environments.