Quite a few images are only used a few times in a few tests. Thus,
the images are being centralized into the agnhost image, reducing
the number of images that have to be pulled and used.
This PR replaces the usage of the following images with agnhost:
- mounttest
- mounttest-user
Additionally, removes the usage of the mounttest-user image and removes
it from kubernetes/test/images. RunAsUser is set instead of having that image.
Since we've added support for RunAsUserName, we can now run some new
tests. However, the [LinuxOnly] tag will have to remain until the
WindowsRunAsUserName feature becomes enabled by default.
Additionally, Containerd supports file mounting on Windows, and some
tests will be able to pass on Windows with Containerd instead of Docker.
Some of the tests cannot pass using Windows nodes due to various reasons:
- seLinuxOptions are not supported on Windows.
- Running as an UID / GID is not supported on Windows.
- file permissions work differently on Windows, and they cannot be set in
the same manner as on Linux.
- individual files cannot be mounted in Windows Containers.
- Cannot create container using Linux image (e.g.: alpine) on Windows.
Because of this, it has been decided to use the "[LinuxOnly]" tag for the
tests which cannot run on Windows because of the mentioned reasons. This way,
when running tests using Windows nodes, those tests can simply be skipped by
adding the "[LinuxOnly]" tag to the ginkgo.skip argument.
Some mounttest related tests are checking the file permissions set on the
container files, but the default file permissions on Windows is 775 instead of
644, causing some tests to fail.
Keep in mind that file permissions work differently on Windows, and setting file
permissions via Kubernetes is not currently supported on Windows.
