As developers ourselves, we know that the containers and Kubernetes world requires a faster cadence of innovation. Our team continues to engage with these communities, and the work we’re doing to improve the Windows containers platform can be seen in Kubernetes releases. One example of that is the new HostProcess feature which became available in alpha with the release of Kubernetes 1.22.
Our approach is grounded in new features our communities want and need being supported not only on the latest release of Windows containers, but any Windows Server supported . And for cases on which additional work is needed to have the feature supported on previous releases, we’re listening to customer feedback to implement and backport where we’re hearing business needs.
Long-Term Servicing Channel
Based on customer feedback and customer adoption patterns, we’ll move to the Long-Term Servicing Channel (LTSC) as our primary release channel. Current Semi-Annual Channel (SAC) releases will continue through their mainstream support end dates, which are May 10, 2022 for Windows Server version 20H2 and December 14, 2021 for Windows Server version 2004.
The focus on container and microservices innovation previously released in the Semi-Annual Channel will now continue with Azure Kubernetes Service (AKS), AKS on Azure Stack HCI, and other platform improvements made in collaboration with the Kubernetes community. And with the Long-Term Servicing Channel, a major new version of Windows Server will be released every 2-3 years, so customers can expect both container host and container images to align with that cadence.
5+5 years of support for all container images
Customers will receive five years of mainstream support and additional 5 years of extended support for all Windows Server 2022 images: Server Core, Nano Server, and the recently announced Server image. This will ensure time to implement, use, and upgrade or migrate at the right time.
Down-level compatibility between host and container images with process isolation
Down-level compatibility between container and host versions has long been an important request from our customers, and we have been working hard to deliver this functionality. Starting with Windows Server 2022, customers will be able to run their Windows Server 2022 container images with either process or Hyper-V isolation on any build of Windows Server 2022 or Windows 11. Customers won’t need to worry whether their container image will run on a newer build of Windows Server 2022 or Windows 11 host. Since the beginning the Windows OS was designed in such a way that its user and kernel modes were always shipped together. Modern container infrastructure breaks this paradigm. Microsoft has undergone a monumental effort in stabilizing the user/kernel boundary to ensure that Windows answers your needs. We've put the OS through rigorous testing to ensure interactions across the Windows ABI work in down-level scenarios. It is for this reason, however, that we are releasing this feature as a preview for customers. We want to ensure flexibility for customer workloads and are committed to addressing any concerns that arise from apps running in down-level scenarios. This helps address the alternating cadences for Windows Server and Windows, previously addressed with Hyper-V isolation. Customers have the flexibility to test out their container workloads directly on a Windows 11 machine using either process or Hyper-V isolation and then deploy the same workload to the cloud.
Windows and developer scenarios
Speaking of developer scenarios using Windows containers, with the launch of Windows Server 2022 we are temporarily enabling forward compatibility for Windows 10 21H1 container hosts to run Windows Server 2022 images using Hyper-V isolation. This will be possible via a specific tag for Windows Server 2022 container images for Server Core, Nano Server, and Server images that will be published specifically for running on Windows 10 21H1 hosts with Hyper-V isolation. This functionality will allow developers running Windows 10 21H1 to kick the tires with Windows Server 2022 images until Windows 11 is generally available (GA) on October 5. Once Windows 11 becomes GA, we will remove these specific images. Customers running Windows 11 and Windows Server 2022 hosts will be able to use the regular images.
If you are running a Windows 10 21H1 container host, you can pull these temporary images via:
To run a new container based on these images, remember you have to specify the Hyper-V isolation mode:
docker run -it --isolation=hyperv mcr.microsoft.com/windows/servercore:win10-21h1-preview powershell
Keep sending your feedback!
We hope you are as excited about the release of Windows Server 2022 and the updates for the Windows container and Kubernetes community as we are. We strive to address your feedback, so as always, please keep comments coming via our GitHub repo or below in the comments section.