My Docker learning short notes

August 10, 2018

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

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