Updates to the Windows Container Runtime support

This post has been republished via RSS; it originally appeared at: Containers articles.

Over the next year, Microsoft will transition support for the Mirantis Container Runtime (MCR, previously known as Docker Engine – Enterprise) to Mirantis support services. Windows Server containers will continue to function regardless of the runtime. The difference will be the coordination of associated technical support previously provided by Microsoft and Mirantis. MCR will continue to be available from and supported by Mirantis. For more information, see Mirantis’s blog here.


What happens if my production workloads run on MCR?
Windows Server containers are a feature of the Windows and Windows Server operating systems and are supported in accordance with the documented support lifecycles. There is no change to the support for any customer experiencing an issue with the operating system functionality. The change is only in reference to the container runtime that builds on top of the operating system functionality.


Customers running Windows Server containers in AKS and AKS-HCI will continue to be supported during the transition to containerd. Microsoft’s decision is in alignment with the recent move made by the Kubernetes community to drop maintenance of dockershim as part of the effort for Kubernetes to remain runtime agnostic through the container runtime interface (CRI).


Best practices for a smooth transition

For customers who cannot immediately transition to AKS or AKS-HCI, there are several options:

  • A supported version of MCR with the same features and capabilities as had been available from Docker is available from Mirantis. This includes support for Docker Swarm. Customers will benefit from updates, patches for security vulnerabilities, as well as global support. Customers using Windows containers in production environments are encouraged to contact Mirantis to pursue this option.

    For Kubernetes environments, Mirantis will continue to provide a supported, CRI compliant container runtime that gives developers the familiar Docker CLI and container management features.

  • Customers can choose to run their Windows Server containers using the runtime from the open-source Moby project. Note that the Moby project does not provide formal support for several enterprise features present in MCR.

At the end of September 2022, Microsoft will no longer maintain the DockerMsftProvider API, and instead customers should go to the Mirantis site for installation. Customers looking to Microsoft for support will still have access to Mirantis services at no cost until September 2022, after which customers may purchase Mirantis’ annual support contract.


The build process for Windows containers using Docker will remain unaffected. Customers will still be able to interact with their container images using the Docker Desktop CLI. Windows containers will continue to work, only the Microsoft-supported runtime for Windows Server is changing.


Both Microsoft and Mirantis are committed to a smooth transition. We encourage you to reach out to us with questions and concerns so we can find the best way to help you through this process.

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