Introduction
Windows Server 2019 is once again generally available. You can pull the new Windows Server 2019 images—including the new ‘Windows’ base image—via:
docker pull mcr.microsoft.com/windows/servercore:1809
docker pull mcr.microsoft.com/windows/nanoserver:1809
docker pull mcr.microsoft.com/windows:1809
Just like the Windows Server 2016 release, the Windows Server Core container image is the only Windows base image in our Long-Term Servicing Channel. For this image we also have an ‘ltsc2019’ tag available to use:
docker pull mcr.microsoft.com/windows/servercore:ltsc2019
The Nanoserver and Windows base images continue to be Semi-Annual Channel releases only.
MCR is the De Facto container source
You can now pull any Windows base image:tag combination from the MCR (Microsoft Container Registry). Whether you’re using a container based on the Windows Server 2016 release, version 1709, version 1803 or any tag in between, you should change your container pull references to the MCR source. Example:
#Here’s the old string for pulling a container
docker pull microsoft/windowsservercore:ltsc2016
docker pull microsoft/nanoserver:1709
#Change the string to the new syntax and use the same tag
docker pull mcr.microsoft.com/windows/servercore:ltsc2016
docker pull mcr.microsoft.com/windows/nanoserver:1709
Or, update your dockerfiles to reference the new image location:
#Here’s the old string to specify the base image
FROM microsoft/windowsservercore:ltsc2016
#Here’s the new, recommend string to specify your base image. Use whichever tag you’d like
FROM mcr.microsoft.com/windows/servercore:ltsc2016
We want to emphasize the MCR is not the place to browse for container images; it’s where you pull images from. Docker Hub continues to be the preferred medium for container image discovery. Steve Lasker’s blog post does a great job outlining the unique value proposition the MCR will bring for our customers.
The Windows Server 2019 VM images for the Azure gallery will be rolling out within the next few days and will come packaged with the most up-to-date Windows Server 2019 container images.
Deprecating the ‘latest’ tag
We are deprecating the ‘latest’ tag across all our Windows base images to encourage better container practices. At the beginning of the 2019 calendar year, we will no longer publish the tag; We’ll yank it from the available tags list.
We strongly encourage you to instead declare the specific container tag you’d like to run in production. The ‘latest’ tag is the opposite of specific; it doesn’t tell the user anything about what version the container actually is apart from the image name. You can read more about version compatibility and selecting the appropriate tag on our container docs.
Conclusion
For more information, please visit our container docs at aka.ms/containers. What other topics & content would you like to see written about containers? Let us know in the comments below or send me a tweet.
Cheers,
Craig Wilhite (@CraigWilhite)