Blog: pkgs.k8s.io: Introducing Kubernetes Community-Owned Package Repositories

sorangutan

Author: Marko Mudrinić (Kubermatic)

On behalf of Kubernetes SIG Release, I am very excited to introduce the Kubernetes community-owned software repositories for Debian and RPM packages: pkgs.k8s.io! The new package repositories are replacement for the Google-hosted package repositories (apt.kubernetes.io and yum.kubernetes.io) that we've been using since Kubernetes v1.5.

This blog post contains information about these new package repositories, what does it mean to you as an end user, and how to migrate to the new repositories.

What you need to know about the new package repositories?

This is an opt-in change; you're required to manually migrate from the Google-hosted repository to the Kubernetes community-owned repositories. See how to migrate later in this announcement for migration information and instructions.
Access to the Google-hosted repository will remain intact for the foreseeable future. However, the Kubernetes project plans to stop publishing packages to the Google-hosted repository in the future. The project strongly recommends migrating to the Kubernetes package repositories going forward.
The Kubernetes package repositories contain packages beginning with those Kubernetes versions that were still under support when the community took over the package builds. This means that anything before v1.24.0 will only be available in the Google-hosted repository.
There's a dedicated package repository for each Kubernetes minor version. When upgrading to a different minor release, you must bear in mind that the package repository details also change.

Why are we introducing new package repositories?

As the Kubernetes project is growing, we want to ensure the best possible experience for the end users. The Google-hosted repository has been serving us well for many years, but we started facing some problems that require significant changes to how we publish packages. Another goal that we have is to use community-owned infrastructure for all critical components and that includes package repositories.

Publishing packages to the Google-hosted repository is a manual process that can be done only by a team of Google employees called Google Build Admins. The Kubernetes Release Managers team is a very diverse team especially in terms of timezones that we work in. Given this constraint, we have to do very careful planning for every release to ensure that we have both Release Manager and Google Build Admin available to carry out the release.

Another problem is that we only have a single package repository. Because of this, we were not able to publish packages for prerelease versions (alpha, beta, and rc). This made testing Kubernetes prereleases harder for anyone who is interested to do so. The feedback that we receive from people testing these releases is critical to ensure the best quality of releases, so we want to make testing these releases as easy as possible. On top of that, having only one repository limited us when it comes to publishing dependencies like cri-tools and kubernetes-cni.

Regardless of all these issues, we're very thankful to Google and Google Build Admins for their involvement, support, and help all these years!

How the new package repositories work?

The new package repositories are hosted at pkgs.k8s.io for both Debian and RPM packages. At this time, this domain points to a CloudFront CDN backed by S3 bucket that contains repositories and packages. However, we plan on onboarding additional mirrors in the future, giving possibility for other companies to help us with serving packages.

Packages are built and published via the OpenBuildService (OBS) platform. After a long period of evaluating different solutions, we made a decision to use OpenBuildService as a platform to manage our repositories and packages. First of all, OpenBuildService is an open source platform used by a large number of open source projects and companies, like openSUSE, VideoLAN, Dell, Intel, and more. OpenBuildService has many features making it very flexible and easy to integrate with our existing release tooling. It also allows us to build packages in a similar way as for the Google-hosted repository making the migration process as seamless as possible.

SUSE sponsors the Kubernetes project with access to their reference OpenBuildService setup (build.opensuse.org) and with technical support to integrate OBS with our release processes.

We use SUSE's OBS instance for building and publishing packages. Upon building a new release, our tooling automatically pushes needed artifacts and package specifications to build.opensuse.org. That will trigger the build process that's going to build packages for all supported architectures (AMD64, ARM64, PPC64LE, S390X). At the end, generated packages will be automatically pushed to our community-owned S3 bucket making them available to all users.

We want to take this opportunity to thank SUSE for allowing us to use build.opensuse.org and their generous support to make this integration possible!

What are significant differences between the Google-hosted and Kubernetes package repositories?

There are three significant differences that you should be aware of:

There's a dedicated package repository for each Kubernetes minor release. For example, repository called core:/stable:/v1.28 only hosts packages for stable Kubernetes v1.28 releases. This means you can install v1.28.0 from this repository, but you can't install v1.27.0 or any other minor release other than v1.28. Upon upgrading to another minor version, you have to add a new repository and optionally remove the old one
There's a difference in what cri-tools and kubernetes-cni package versions are available in each Kubernetes repository
- These two packages are dependencies for kubelet and kubeadm
- Kubernetes repositories for v1.24 to v1.27 have same versions of these packages as the Google-hosted repository
- Kubernetes repositories for v1.28 and onwards are going to have published only versions that are used by that Kubernetes minor release
  - Speaking of v1.28, only kubernetes-cni 1.2.0 and cri-tols v1.28 are going to be available in the repository for Kubernetes v1.28
  - Similar for v1.29, we only plan on publishing cri-tools v1.29 and whatever kubernetes-cni version is going to be used by Kubernetes v1.29
The revision part of the package version (the -00 part in 1.28.0-00) is now autogenerated by the OpenBuildService platform and has a different format. The revision is now in the format of -x.y, e.g. 1.28.0-1.1

Does this in any way affect existing Google-hosted repositories?

The Google-hosted repository and all packages published to it will continue working in the same way as before. There are no changes in how we build and publish packages to the Google-hosted repository, all newly-introduced changes are only affecting packages publish to the community-owned repositories.

However, as mentioned at the beginning of this blog post, we plan to stop publishing packages to the Google-hosted repository in the future.

How to migrate to the Kubernetes community-owned repositories?

Debian, Ubuntu, and operating systems using `apt`/`apt-get`

Replace the apt repository definition so that apt points to the new repository instead of the Google-hosted repository. Make sure to replace the Kubernetes minor version in the command below with the minor version that you're currently using:
```
echo "deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.28/deb/ /" | sudo tee /etc/apt/sources.list.d/kubernetes.list
```
Download the public signing key for the Kubernetes package repositories. The same signing key is used for all repositories, so you can disregard the version in the URL:
```
curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.28/deb/Release.key | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg
```
Update the apt package index:
```
sudo apt-get update
```

CentOS, Fedora, RHEL, and operating systems using `rpm`/`dnf`

Replace the yum repository definition so that yum points to the new repository instead of the Google-hosted repository. Make sure to replace the Kubernetes minor version in the command below with the minor version that you're currently using:

cat <<EOF | sudo tee /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://pkgs.k8s.io/core:/stable:/v1.28/rpm/
enabled=1
gpgcheck=1
gpgkey=https://pkgs.k8s.io/core:/stable:/v1.28/rpm/repodata/repomd.xml.key
exclude=kubelet kubeadm kubectl cri-tools kubernetes-cni
EOF

Can I rollback to the Google-hosted repository after migrating to the Kubernetes repositories?

In general, yes. Just do the same steps as when migrating, but use parameters for the Google-hosted repository. You can find those parameters in a document like "Installing kubeadm".

Why isn’t there a stable list of domains/IPs? Why can’t I restrict package downloads?

Our plan for pkgs.k8s.io is to make it work as a redirector to a set of backends (package mirrors) based on user's location. The nature of this change means that a user downloading a package could be redirected to any mirror at any time. Given the architecture and our plans to onboard additional mirrors in the near future, we can't provide a list of IP addresses or domains that you can add to an allow list.

Restrictive control mechanisms like man-in-the-middle proxies or network policies that restrict access to a specific list of IPs/domains will break with this change. For these scenarios, we encourage you to mirror the release packages to a local package repository that you have strict control over.

What should I do if I detect some abnormality with the new repositories?

If you encounter any issue with new Kubernetes package repositories, please file an issue in the kubernetes/release repository.

https://kubernetes.io/blog/2023/08/15/pkgs-k8s-io-introduction/