What is a Docker registry?

A Docker registry is a storage for Docker images. Images can be uploaded there (push) and downloaded from there (pull), in order to then run containers.

The essential facts:

• Registry = image repository (an analog of a Git storage, but for Docker images).
• Allows sharing images within a team or distributing them publicly.
• Works as a source for deployment - a server or CI/CD downloads the image directly from the registry.
• Supports versions (tags) - an image can be stored as v1, v2, latest and rolled back when needed.

Examples of registries:

• Docker Hub - public by default.
• GitHub Container Registry / GitLab Registry - for teams and CI.
• Private registry - a company's own closed registry.

If an image is a "container template", then a registry is a "remote shelf where those templates are kept and taken from".