Docker: The Container Revolution

Before Docker, “it works on my machine” was the most common excuse in software development. Docker fixed this by packaging the application and its environment together.

What is a Container?

A container is a lightweight, standalone, executable package of software that includes everything needed to run an application: code, runtime, system tools, system libraries and settings.

Images vs Containers

• Image: The blueprint (read-only). Like a Class in OOP.
• Container: The running instance of an image. Like an Object in OOP.

Basic Commands

# Pull an image from Docker Hub
docker pull nginx

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

# List running containers
docker ps

# Stop a container
docker stop <container_id>

Dockerfile

You define your image using a Dockerfile:

FROM node:18
WORKDIR /app
COPY . .
RUN npm install
CMD ["npm", "start"]

Conclusion

Docker is fundamental skill for any developer today. It is the foundation of modern DevOps and Cloud Native development.