Docker

1. Docker Components

Docker Image: A lightweight, stand-alone, executable package that includes everything needed to run a piece of software.

Docker Container: A runtime instance of a Docker image.

Docker Hub: A cloud-based registry service where Docker users and partners create, test, store, and distribute container images.

Dockerfile: A text document that contains all the commands a user could call on the command line to assemble an image.

Docker Compose: A tool for defining and running multi-container Docker applications.

Docker Engine: A client-server application managing Docker images, containers, networks, and volumes.

Docker Daemon: Listens for Docker API requests and manages Docker objects.

Docker Client: The interface used to interact with the Docker daemon.

2. Commands

docker --version: Display Docker version.

docker info: Display system-wide information.

docker run image: Run a Docker container from an image.

docker ps: List running Docker containers.

docker ps -a: List all Docker containers.

docker stop container_id: Stop a running container.

docker rm container_id: Remove a Docker container.

docker images: List Docker images.

docker rmi image_id: Remove a Docker image.

3. Dockerfile

FROM image: Set the base image.

RUN command: Run a command.

CMD command: Set a default command that will run when the container starts.

ENV VAR=VALUE: Set environment variables.

ADD source destination: Copy files from source to the container's filesystem at the destination.

COPY source destination: Copy new files or directories from source and add them to the container.

ENTRYPOINT command: Configure a container to run as an executable.

LABEL: Adds metadata to an image.

EXPOSE: Informs Docker that the container listens on specified network ports.

4. Compose

docker-compose up: Create and start containers.

docker-compose down: Stop and remove containers, networks, images, and volumes.

docker-compose build: Build or rebuild services.

docker-compose logs: View output from containers.

docker-compose restart: Restart services.

5. Networking

docker run -d image: Run a Docker container in detached mode.

docker run -p host_port:container_port image: Map a port from the host to a container.

docker run -v host_volume:container_volume image: Mount a volume from the host to a container.

docker run -e VAR=VALUE image: Set environment variables in a container.

docker network ls: List networks.

docker network create network: Create a network.

docker network rm network: Remove a network.

6. Volumes

docker volume ls: List volumes.

docker volume create volume: Create a volume.

docker volume rm volume: Remove a volume.

7. Object Commands

docker inspect container_id/image_id: Return low-level information on Docker objects.

docker build -t tag .: Build a Docker image with a tag from a Dockerfile in the current directory.

docker tag image new_tag: Tag an image with a new tag.

docker commit container image: Create a new image from a container's changes.

docker history image: Show the history of an image.

8. System Commands

docker info: Displays system-wide information.

docker version: Shows Docker version information.

docker system df: Shows Docker disk usage.

docker system events: Gets real-time events from the server.

docker system prune: Removes unused data.

9. Docker Swarm

docker swarm init: Initialize a swarm.

docker swarm join: Join a node to a swarm.

docker node ls: List nodes in a swarm.

docker service create image: Create a service.

docker service ls: List services in a swarm.

docker service rm service: Remove a service.

10. Security

docker secret create secret file: Create a secret from a file.

docker secret ls: List secrets.

docker secret rm secret: Remove a secret.

Docker Security Scanning: 🔍🛡 Scans Docker images for vulnerabilities.

Docker Content Trust: 🤝🔏 Uses digital signatures for data in Docker registries.

Docker Secrets: 🤫🔐 Manage sensitive data (passwords, SSH keys, SSL certificates).

11. Advanced Commands

docker save image > file: Save an image to a tar archive.

docker load < file: Load an image from a tar archive.

docker stats: Display live container resource usage statistics.

Docker Best Practices

Container Immutability: 🧱🔒 Always create a new container instead of updating a running one.

Single Process per Container: 🚀🔧 Each container should handle a single concern.

Leverage Build Cache: 🏗🔍 Docker caches results for faster builds.

Use .dockerignore: 🙈🔍 Exclude unnecessary files from builds.

Service Scaling: 🔢🔧 Scale services up or down in Docker Swarm.

Load Balancing: ⚖🚀 Docker has built-in load balancing for replicated services.