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What is Docker Hub?

Learn that Docker Hub is a public registry.

What is Docker Hub?

A registry is the server where images are stored and shared. Docker Hub is the default public registry. If no registry is written in the image name, Docker Hub is assumed; if no user name is written, the official library repository is used:

nginx              = docker.io/library/nginx:latest
ali/api:1.0        = docker.io/ali/api:1.0
ghcr.io/ali/api    = GitHub Container Registry

For free accounts an hourly limit applies to anonymous pulls; logging in raises this limit.

Repositories and access

On Docker Hub each repository can be public or private. Anyone can pull from public repositories; only owners and team members can push. The tags in a repository can be seen in the web interface or with a script:

docker pull ali/api:1.0          # no login needed if public
docker search --limit 3 postgres # searching on Hub

Practice Pull from different registries

Write two commands: pull nginx:alpine with Docker Hub's full name (docker.io/library/...); then pull the ghcr.io/ali/api:1.0 image from the GitHub registry.

Starter code

terminal
# buraya yaz

Sample solution

terminal
docker pull docker.io/library/nginx:alpine
docker pull ghcr.io/ali/api:1.0

Expected output

alpine: Pulling from library/nginx
Status: Image is up to date for nginx:alpine
1.0: Pulling from ali/api
Status: Downloaded newer image for ghcr.io/ali/api:1.0

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 What is the full equivalent of the image name redis?

  • docker.io/library/redis:latest Correct answer
  • redis.io/redis
  • docker.io/redis/redis
  • localhost/redis

Explanation: The registry, namespace and tag are completed with defaults.

2 Pull the image by its full name.

Question 
docker pull ____/library/nginx:alpine
Answer 
docker pull docker.io/library/nginx:alpine

Explanation: Docker Hub's registry address is docker.io.

3 Match.

Term Meaning
docker.io Docker Hub
library/ Official image namespace
ghcr.io GitHub registry
private depo Only authorized pull

All lessons in Beginner

1 What is Docker?

  1. What is Docker?
  2. Containers and virtual machines
  3. Images and containers
  4. Docker architecture
  5. Use cases
  6. Summary - What is Docker

2 Installation and first commands

  1. Installing Docker
  2. docker version
  3. docker info
  4. The hello-world container
  5. Docker Desktop
  6. Summary - Installation

3 First container

  1. docker run basics
  2. Running in the background
  3. docker ps
  4. docker stop and rm
  5. docker logs
  6. Summary - First container

4 Dockerfile basics

  1. What is a Dockerfile?
  2. The FROM instruction
  3. The RUN instruction
  4. COPY and ADD
  5. CMD and ENTRYPOINT
  6. Summary - Dockerfile

5 Build and images

  1. docker build
  2. Tagging images
  3. Build context
  4. Layers and cache
  5. .dockerignore
  6. Summary - Build

6 docker run options

  1. Interactive mode
  2. Naming containers
  3. Restart policy
  4. Working directory
  5. Switching users
  6. Summary - docker run

7 Image management

  1. docker images
  2. docker rmi
  3. docker pull
  4. docker push
  5. docker tag
  6. Summary - Image management

8 Port mapping

  1. The port concept
  2. The -p flag
  3. Multiple ports
  4. Random ports
  5. IP binding
  6. Summary - Port mapping

9 Volumes and data

  1. Data persistence
  2. Named volumes
  3. The -v flag
  4. Bind mounts
  5. Volume management
  6. Summary - Volumes

10 Environment variables

  1. The -e flag
  2. The ENV instruction
  3. The ARG instruction
  4. env-file
  5. The WORKDIR instruction
  6. Summary - Environment

11 Project: docker-compose

  1. Compose design
  2. Service definition
  3. Database service
  4. Volume and network
  5. Putting it together - compose

12 Docker Hub and registry

  1. What is Docker Hub?
  2. docker login
  3. Searching images
  4. Official images
  5. Private registry
  6. Summary - Registry

13 Network basics

  1. Network drivers
  2. docker network ls
  3. Bridge network
  4. Container connectivity
  5. Publishing ports
  6. Summary - Network

14 Beginner final

  1. Challenge - Dockerfile
  2. Challenge - Build and run
  3. Challenge - Volume
  4. Challenge - Compose
  5. Challenge - Beginner project