That's the last beta of this edition of Windows Server before it's released to manufacturing. In the interim, Docker plans to ensure its ecosystem supports Windows Server, both in the OS itself and elsewhere.
The new Docker beta for Windows Server rolls in a couple of features vital to making Windows a first-class citizen of the Docker world. For one, Windows images on Docker Hub now have full support for the
pull commands, meaning Docker Hub should start featuring more Windows-specific images to use.
Another potentially major addition is a prototype of the ability to to perform multiplatform builds, pushes, and pulls for Docker images designed for multiple OSes and CPU architectures.
This isn't done by packing multiple binary images into a single container, a la Macintosh Universal Binary. Instead, the Docker Image Manifest -- the file format that describes what's inside a given image -- now supports storing metadata about the CPU architecture and OS for the app. Pull requests sent to the Docker registry serve up the version that matches the client.
But building the apps for the appropriate platform is entirely up to the developer and the language/runtime combo they use. For example, Docker is written in Go, which supports cross-compilation, but Go is hardly the only language Docker apps will be written in.
Still, it's a major step toward a culture of software use and distribution for Docker where different platforms are encouraged to take advantage of common resources, rather than similar options built in parallel.