Donating Docker Distribution to the CNCF

Justin Cormack

Feb 04 2021

We are happy to announce that Docker has contributed Docker Distribution to the Cloud Native Computing Foundation (CNCF). Docker is committed to the Open Source community and open standards for many of our projects, and this move will ensure Docker Distribution has a broad group maintaining what is the foundation for many registries. 

What is Docker Distribution?

Distribution is the open source code that is the basis of the container registry that is part of Docker Hub, and also many other container registries. It is the reference implementation of a container registry and is extremely widely used, so it is a foundational part of the container ecosystem. This makes its new home in the CNCF highly appropriate.

Docker Distribution was a major rewrite of the original Registry code which was written in Python and was a much earlier design not using content addressed storage. This new version, written in Go, was designed to be an extensible library, so that different backends and subsystems could be designed. Docker formed the Open Container Initiative (OCI) in 2015, in the Linux Foundation, in order to standardise the specifications for the container ecosystem, including the registry and image formats.

Why are we donating Docker Distribution to the CNCF?

There are now many registries, with a lot of companies and organizations providing registries internally or as a service. Many of these are based on the code in Docker Distribution, but we found that many people had small forks and changes that they were not contributing to the upstream version, and the project needed a broader group of maintainers. To make the project clearly an industry wide collaboration, hosting it in the CNCF was the obvious place, as it is the home of many successful collaborative projects, such as Kubernetes and Containerd.

We approached the major users of the Docker Distribution code at scale to become maintainers of the project. This includes maintainers from Docker, GitHub, GitLab, Digital Ocean, Mirantis and the Harbor project which is itself a graduated CNCF project that extends the core registry with other services. In addition, we have invited a maintainer from the OCI, and we are open to more participation in the future. The project is now simply called “Distribution” and can be found at

The Distribution project has been accepted into the CNCF Sandbox, but as it is a mature project we will be proposing that it moves to incubation shortly. We welcome the new maintainers and look forward to the new contributions and future for the project in the CNCF.