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Docker Quickstart

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Docker is an open-source platform that simplifies building, shipping, and running applications using containers. A container is a lightweight, portable unit that bundles an application with all its dependencies, ensuring it runs consistently across different environments.

Docker streamlines local development by offering isolated, consistent, and reproducible environments for applications and their dependencies. This helps eliminate common problems like environment mismatches and simplifies the setup process across different systems.

✅ Key Benefits

  • Consistent environments – Eliminates "it works on my machine" issues by replicating the same setup everywhere.
  • Isolated dependencies – Each project runs in its own container without interfering with others.
  • Fast setup and teardown – Quickly start or stop environments using Docker commands or docker-compose.
  • Reproducible setups – Easily share and version your development environment with teammates.
  • Supports multi-service apps – Run databases, APIs, and other services together locally.
  • Great tooling support – Works well with IDEs, CI/CD pipelines, and testing tools.
  • Lightweight and efficient – Containers are faster and use fewer resources than full virtual machines.

🚀 Docker Quickstart

1. Verify Docker is installed

docker --version

Make sure Docker Engine & CLI are properly set up.

2. Download an image

docker pull <image>:<tag>

Grabs an image (e.g., nginx:latest) from Docker Hub or another registry.

3. Launch a container

docker run [OPTIONS] <image> [COMMAND] [ARGS…]

Creates and starts a container from the image.
Typical options include:

  • -d: run detached
  • -p host:container: map ports
  • --name <name>: name your container

4. View running containers

docker ps            # show active containers  
docker ps -a         # include stopped/exited ones

Helpful for tracking container status and IDs.

5. Execute a command inside a container

docker exec -it <container> <command>

Example: docker exec -it my_app bash for an interactive shell.

6. Stop, restart, or kill

docker stop <container>     # graceful shutdown  
docker restart <container>  # restart container  
docker kill <container>     # immediate force-stop

Use kill only if stop doesn’t respond.

7. Make a snapshot of changes

docker commit <container> <new-image>:<tag>

Captures container state into a new image.

8. Push images to a registry

docker login <registry>     # authenticate  
docker push <image>:<tag>   # upload

Share your image via Docker Hub or private registries.

9. Clean up

docker rm <container>       # remove container  
docker rmi <image>          # remove image

Options:

  • -f: force removal
  • -v: remove attached volumes

✅ Summary Table

Step Command Example
Check version docker --version
Pull image docker pull ubuntu:latest
Run container docker run -d --name web -p 80:80 nginx
List containers docker ps -a
Exec into container docker exec -it web bash
Stop container docker stop web
Commit changes docker commit web web_snapshot:1.0
Push image docker login → docker push web_snapshot:1.0
Cleanup docker rm web → docker rmi web_snapshot:1.0

These commands cover the basic lifecycle: install → pull → run → interact → stop → save → share → clean. Once you're comfortable, you can explore more advanced features like building from Dockerfiles, managing networks/volumes, and orchestrating multi-container applications.