Docker for Web Hosting: A Beginner-Friendly Introduction

What is Docker?

Docker packages your application and its dependencies into a container — a lightweight, portable unit that runs consistently everywhere. Think of it as a shipping container for software.

Why Docker for Hosting?

Consistency

"It works on my machine" becomes "It works everywhere":

Same environment in development and production
No dependency conflicts
Reproducible deployments

Isolation

Each container runs independently:

One container crashing doesn't affect others
Different PHP versions for different sites
Security isolation between applications

Efficiency

Containers are lightweight:

Start in seconds (vs minutes for VMs)
Share the host OS kernel
Use less memory and disk

Core Concepts

Images

A read-only template containing your application:

dockerfile

# Dockerfile
FROM php:8.2-apache
COPY ./src /var/www/html
RUN docker-php-ext-install mysqli pdo pdo_mysql
EXPOSE 80

Containers

A running instance of an image:

bash

docker run -d -p 80:80 --name my-website my-image

Docker Compose

Define multi-container applications:

yaml

# docker-compose.yml
services:
  web:
    image: wordpress:latest
    ports:
      - "80:80"
    environment:
      WORDPRESS_DB_HOST: db
      WORDPRESS_DB_PASSWORD: secret
  db:
    image: mysql:8.0
    environment:
      MYSQL_ROOT_PASSWORD: secret
    volumes:
      - db-data:/var/lib/mysql
volumes:
  db-data:

Common Docker Commands

bash

# Container management
docker ps                    # List running containers
docker ps -a                 # List all containers
docker start container_name  # Start container
docker stop container_name   # Stop container
docker logs container_name   # View logs
docker exec -it container_name bash  # Shell into container

# Image management
docker images               # List images
docker pull nginx:latest    # Download image
docker build -t myapp .     # Build from Dockerfile

# Cleanup
docker system prune         # Remove unused data

Hosting Multiple Sites

Docker makes it easy to host multiple websites on one server:

yaml

services:
  site1:
    image: wordpress:latest
    environment:
      VIRTUAL_HOST: site1.com
  site2:
    image: wordpress:latest
    environment:
      VIRTUAL_HOST: site2.com
  nginx-proxy:
    image: jwilder/nginx-proxy
    ports:
      - "80:80"
      - "443:443"
    volumes:
      - /var/run/docker.sock:/tmp/docker.sock:ro

Conclusion

Docker is the future of web hosting infrastructure. Start with Docker Compose for simple multi-container setups, and you will quickly appreciate the consistency, isolation, and efficiency it provides.