Removes any reference from the registry gcr.io/kubernetes-e2e-test-images in
kubernetes/kubernetes, replacing it with k8s.gcr.io/kubernetes-e2e-test-images.
In some cases, the images had to be updated since a few things have changed since
their original implementation, most notably being the fact that some of the images
have been centralized into the agnhost image.
Co-Authored-By: Claudiu Belu <cbelu@cloudbasesolutions.com>
We can cache the powershell-helper image's results into a scratch Linux image using
docker buildx. This will allow us to spend less time pulling the data we need from the
powershell-helper image when we need it.
Additionally, docker buildx might have some issues with cross-registry images, so this
will allow us to circumvent it.
A few details about the image builder postsubmit jobs changed, so the README had to
be updated as well.
Added a few extra bits of information regarding the Windows images.
We cannot have any RUN commands in the Windows stage when using docker buildx,
which is why we were using the busybox-helper image. The purpose of the image
was to contain a few things that we would obtain by running a few commands:
- symlinks for the busybox binary
- run vcredist_x64.exe which would also give us the vcruntime140.dll which is
necessary for dig or httpd.
There are alternatives to the commands above that can be achieved in a Linux stage
as well:
- we can create the symlinks in a Linux stage with ln -s. Copying them over to
Windows will allow them to work just as well as if they were being copied over
from a Windows image. The 'Files\' prefix issue to the symlink target still persists.
- we can download the vcruntime140.dll directly, allowing us to skip the vcredist_x64.exe
installation.
Currently, some of the E2E test images have Windows support, and one of the goals is for most of
them to have Windows support. For that, the Image Builder is currently building those Windows
container images using a few Windows Server nodes (for 1809, 1903, 1909) with Remote Docker
enabled which are hosted on an azure subscription dedicated for CNCF.
With this, the Windows nodes dependency is removed entirely, as the images can be also built with
docker buildx. One additional benefit to this is that adding new supported Windows OS versions
to the E2E test images manifest lists becomes a lot easier (we wouldn't have to create a new Windows
Server node that matches that new OS version, assign DNS name, update certificates, etc.), and it
also becomes easier for other people to build their own E2E windows test images.
However, some dependencies are still required to run on a Windows machine. To solve this, we can
just pull helper images: e2eteam/powershell-helper:6.2.7 and e2eteam/busybox-helper:1.29.0. Their
Dockerfiles and a Makefile for them has been included in this commit. If any change is required to
them, then a new image will be built and tagged under a different version, but they are pretty
straight-forward and shouldn't require changes.
However, there is a small concern when it comes to the build time: Windows servercore images are
very large (for example, mcr.microsoft.com/windows/servercore:ltsc2019 is 4.99GB uncompressed, and
about ~2 GB compressed - those images are already cached on the Windows Server builder nodes, so
this isn't an issue there), and we currently support 1809, 1903, and 1909 (soon to add 2004).
This can lead to build times that are too big.
We have changed the base image to nanoserver (uncompressed size: 250MB), but some images still
require some DLLs or some other dependencies that can be fetched from a servercore image.
A separate job has been defined that would build a scratch windows-servercore-cache image monthly,
and then we can just get those dependencies from this cache, which will be very small.
This would be preferred, as the Windows images update periodically, and those dependencies
could be updated as well.
