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docker login

Learn to log in to a registry with docker login.

docker login

docker login authenticates to a registry; if no address is given it connects to Docker Hub. Using an access token instead of a password is recommended: its scope is limited and it can be revoked on its own:

docker login                         # Docker Hub, interactive
docker login ghcr.io -u ali          # another registry
docker logout ghcr.io

Secure login

Piping the token from an environment variable to standard input keeps it off the command line:

echo "$GHCR_TOKEN" | docker login ghcr.io -u ali --password-stdin
Login Succeeded

The credentials are saved to ~/.docker/config.json or, if configured, the operating system's credential store. On shared machines, docker logout is done when finished.

Practice Logging in on CI

Write two commands: log in to ghcr.io as user ali by piping the $GHCR_TOKEN variable to standard input; then push ghcr.io/ali/api:1.0.

Starter code

terminal
# buraya yaz

Sample solution

terminal
echo "$GHCR_TOKEN" | docker login ghcr.io -u ali --password-stdin
docker push ghcr.io/ali/api:1.0

Expected output

Login Succeeded
The push refers to repository [ghcr.io/ali/api]
1.0: digest: sha256:4a5b… size: 1789

Questions and answers

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

1 How should the password be given to docker login in a CI pipeline?

  • On the command line with -p
  • By writing it in the Dockerfile
  • By adding it to the image tag
  • From standard input with --password-stdin Correct answer

Explanation: A password given with -p shows up in the process list and shell history.

2 Read the password from standard input.

Question 
echo "$TOKEN" | docker login -u ali ____
Answer 
echo "$TOKEN" | docker login -u ali --password-stdin

Explanation: --password-stdin takes the password from the pipe.

3 Match.

Term Meaning
docker login Authenticates
docker logout Removes credentials
access token Limited, revocable
config.json Credential record

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