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Image Registries

A Docker Image Registry is a centralized, server-side storage and distribution system designed to manage container images. It acts as a library where developers can upload (push) their built images and from which others can download (pull) them to run as containers.

Image Registry

How It Works​

  • The Workflow: When a developer builds an image, they "push" it to a registry. A user or an automated deployment system (like a CI/CD pipeline) then "pulls" that image from the registry to run it in a different environment.
  • Registry vs. Repository:
    • A Registry is the entire service (the "warehouse").
    • A Repository is a collection of related images within that registry, usually organized by project (e.g., my-org/my-app).
    • Images are often identified by Tags (e.g., my-app:v1.0), which represent specific versions of the software.

Types of Registries​

  1. Public Registries: These are accessible to anyone on the internet. They are typically used for sharing open-source software and official images. Example: Docker Hub is the default public registry.
  2. Private Registries: These are restricted, offering secure, controlled access. They are essential for enterprises to store proprietary code and internal applications.
  • Docker Hub: The industry-standard public registry.
  • Amazon Elastic Container Registry (ECR): AWS-native, highly integrated with AWS services.
  • Google Artifact Registry (GAR): Google Cloud’s service.
  • Azure Container Registry (ACR): Microsoft Azure’s managed registry service.
  • Self-Hosted/Third-Party: Harbor, JFrog Artifactory, GitLab Container Registry.