Image registries

A registry is a storage server for Docker images. Registries can be public or private, and there are free public registries and commercial registry servers that allow fine-grained access control for images. Images are stored with a unique name within the registry. Anyone with access can upload an image by running docker image push and download an image by running docker image pull.

The most popular registries are the public ones hosted by Docker:

• Docker Hub is the original registry, which has become hugely popular for open source projects in the Linux ecosystem. It has over 600,000 images stored and has hosted over 12 billion image pulls.
• Docker Cloud is where you store images you build yourself, and you can configure images to be public or private. It's suitable for internal products, where you can limit access to the images. You can set up Docker Cloud to automatically build images from Dockerfiles stored in GitHub—currently, this is supported only for Linux-based images, but Windows support is coming soon.
• Docker Store is where you get commercial software, pre-packaged as Docker images. Vendors are increasingly supporting Docker as a platform for their own applications, and you will find software from Microsoft, Oracle, HPE, and more on Docker Store.

In a typical workflow, you might build images as part of a CI pipeline and push them to a registry if all the tests pass. The image is then available for other users to run your application in a container.