Docker Registry Explained: Tag, Login, Push and Pull Images

Docker Registry Explained#

A Docker registry stores and distributes container images. This guide explains Docker Hub, private registries, image names, tags, login, push, pull, CI/CD usage, and security best practices.

What is a Docker registry?#

A registry is a place where Docker images are stored. Developers and CI/CD pipelines push images to a registry, and servers or Kubernetes clusters pull images from it.

Image naming format#

registry.example.com/team/app:v1.0.0 nginx:1.27 myuser/myapp:latest

Pull an image#

docker pull nginx:latest

Build and tag an image#

docker build -t myapp:1.0 . docker tag myapp:1.0 myuser/myapp:1.0

Login and push#

docker login docker push myuser/myapp:1.0

Pull and run#

docker pull myuser/myapp:1.0 docker run -d -p 3000:3000 myuser/myapp:1.0

Common registry options#

• Docker Hub
• GitLab Container Registry
• GitHub Container Registry
• AWS Elastic Container Registry
• Azure Container Registry
• Google Artifact Registry
• Self-hosted private registry

CI/CD usage example#

docker build -t "$CI_REGISTRY_IMAGE:$CI_COMMIT_SHORT_SHA" . docker push "$CI_REGISTRY_IMAGE:$CI_COMMIT_SHORT_SHA"

Tagging strategy#

• Tag — Use
• latest — Convenient but risky for production.
• Commit SHA — Good for traceability.
• Semantic version — Good for releases, such as v1.2.0 .
• Environment tag — Useful for dev/staging pointers.

Common mistakes#

• Using only latest in production.
• Not scanning pushed images.
• Pushing secrets inside images.
• Using one shared registry account for everyone.
• Not cleaning old images and tags.

Best practices#

• Use immutable tags for releases.
• Use least-privilege registry tokens.
• Scan images before deployment.
• Document image naming standards.
• Clean unused tags carefully.

Related Melochip guides#

• Docker Learning Path
• GitLab Docker Build Pipeline
• Artifact Repository Managers

Official references#

• Docker Hub repositories
• docker image push reference