My Docker learning short notes

I had this note from long time in my Evernotes, I thought I should have post it here, so someone might find it useful. This is just Docker basics and commonly used commands that I've collected over time.

Why Docker?

Docker enables containerization - running applications in containers instead of virtual machines. Important notes:

• Containers are not VMs - they have different benefits
• Provides standardization across environments
• Enables continuous deployment from development to production
• Ensures consistency using the same container image throughout the deployment process

Key Benefits:

• Self-contained environments
• Isolated from other applications
• Runs almost everywhere (especially in the Cloud)
• Small and lightweight
• Highly scalable
• Fast deployment

Core Concepts

Images

An image is an executable package containing everything needed to run an application:

• Application code
• Runtime environment
• Libraries
• Environment variables
• Configuration files

Containers

A container is a runtime instance of an image - what the image becomes in memory when executed (an image with state, or a user process).

Dockerfile

A Dockerfile is a text document containing all commands needed to build a Docker image. It's the blueprint for creating Docker images.

Essential Docker Commands

Version Information

docker --version      # or docker -v
docker-compose --version
docker-machine --version
   

Basic Container Operations

# Run containers
docker run hello-world                     # Test installation
docker run -d -p 80:80 --name webserver nginx  # Run nginx server
docker run -p 4000:80 friendlyhello       # Run with port mapping
docker run -d -p 4000:80 friendlyhello    # Run in detached mode

# Container management
docker container ls                        # List running containers
docker container ls -a                     # List all containers
docker container stop [container-id]       # Stop container
docker container rm [container-id]         # Remove container
docker logs [container-name]              # View container logs

# Image management
docker image ls                           # List images
docker image rm [image-id]                # Remove image
docker build -t [name] .                  # Build image from Dockerfile
   

Container Access

# Enter container shell
docker exec -it [container-id/name] sh
docker exec -it [container-id] bash

# Get container IP
docker inspect [container-id] | grep "IPAddress"
   

Docker Swarm Commands

docker stack ls                          # List stacks/apps
docker stack deploy -c [compose-file] [app-name]  # Deploy app
docker service ls                        # List running services
docker swarm leave --force              # Leave swarm cluster
   

Image Registry Operations

docker login                            # Login to Docker Hub
docker tag [image] username/repository:tag  # Tag image
docker push username/repository:tag     # Push to registry
docker pull username/repository:tag     # Pull from registry
   

Note: Replace text in [brackets] with your actual values when using these commands.

Best Practices

• Always tag your images with meaningful versions
• Use appropriate base images
• Remove unused containers and images regularly
• Use docker-compose for multi-container applications
• Keep container images small