Thursday, 4 July 2019

Docker Registries and Repositories - Is there a difference ? ( Hint, yes, there really is )

This came up in discussion today, and one of my colleagues pointed me here: -

Difference between Docker registry and repository

Docker registry is a service that is storing your docker images.

Docker registry could be hosted by a third party, as public or private registry, like one of the following registries:

    Docker Hub,
    Quay,
    Google Container Registry,
    AWS Container Registry

or you can host the docker registry by yourself
(see https://docs.docker.com/docker-trusted-registry/ for more details).

Docker repository is a collection of different docker images with same name, that have different tags. Tag is alphanumeric identifier of the image within a repository.

For example see https://hub.docker.com/r/library/python/tags/. There are many different tags for the official python image, these tags are all members of the official python repository on the Docker Hub. Docker Hub is a Docker Registry hosted by Docker.

To find out more read:

    https://docs.docker.com/registry/
    https://github.com/docker/distribution

IBM Cloud also helped me here, in that I have an IBM Cloud Container Registry service, aka ICCR, within which I have access to several Repositories, and the ICCR UI helpfully tells me: -

A repository is a set of related images with the same name, but different tags.



which is, as they say, nice 😂

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Note to self - use kubectl to query images in a pod or deployment

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