k8s.gcr.io Redirect to registry.k8s.io - What You Need to Know
FYI if you are running an older k8s cluster, here's a heads up from the community.
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From: 'Chris Short' via leads <leads@...>
Date: Mon, Mar 13, 2023 at 3:02 AM
Subject: k8s.gcr.io Redirect to registry.k8s.io - What You Need to Know
To: <dev@...>, <leads@...>
Last Friday, the following was published in the Kubernetes blog and is available at https://k8s.io/image-registry-change:--
TL;DR: What you need to know about this change
If you think you may be impacted, or would like to know more about this change, please keep reading.
How can I check if I am impacted?
To test connectivity to registry.k8s.io and being able to pull images from there, here is a sample command that can be executed in the namespace of your choosing:
When you run the command above, here’s what to expect when things work correctly:
What kind of errors will I see if I’m impacted?
Errors may depend on what kind of container runtime you are using, and what endpoint you are routed to, but it should present such as
Below is an example error message showing a proxied deployment failing to pull due to an unknown certificate:
What images will be impacted?
ALL images on k8s.gcr.io will be impacted by this change. k8s.gcr.io hosts many images beyond Kubernetes releases. A large number of Kubernetes subprojects host their images there as well. Some examples include the
I am impacted. What should I do?
For impacted users that run in a restricted environment, the best option is to copy over the required images to a private registry or configure a pull-through cache in their registry.
There are several tools to copy images between registries; crane is one of those tools, and images can be copied to a private registry by using
How can I find which images are using the legacy registry, and fix them?
Option 1: See the one line kubectl command in our earlier blog post:
Option 2: A
If you have krew installed, you can install it with:
and generate a report with:
For alternate methods of install and example output, check out the repo: kubernetes-sigs/community-images.
Option 3: If you do not have access to a cluster directly, or manage many clusters - the best way is to run a search over your manifests and charts for "k8s.gcr.io".
Option 4: If you wish to prevent k8s.gcr.io based images from running in your cluster, example policies for Gatekeeper and Kyverno are available in the AWS EKS Best Practices repository that will block them from being pulled. You can use these third-party policies with any Kubernetes cluster.
Option 5: As a LAST possible option, you can use a Mutating Admission Webhook to change the image address dynamically. This should only be considered a stopgap till your manifests have been updated. You can find a (third party) Mutating Webhook and Kyverno policy in k8s-gcr-quickfix.
Why did Kubernetes change to a different image registry?
k8s.gcr.io is hosted on a custom Google Container Registry (GCR) domain that was set up solely for the Kubernetes project. This has worked well since the inception of the project, and we thank Google for providing these resources, but today, there are other cloud providers and vendors that would like to host images to provide a better experience for the people on their platforms. In addition to Google’s renewed commitment to donate $3 million to support the project's infrastructure last year, Amazon Web Services announced a matching donation during their Kubecon NA 2022 keynote in Detroit. This will provide a better experience for users (closer servers = faster downloads) and will reduce the egress bandwidth and costs from GCR at the same time.
For more details on this change, check out registry.k8s.io: faster, cheaper and Generally Available (GA).
Why is a redirect being put in place?
The project switched to registry.k8s.io last year with the 1.25 release; however, most of the image pull traffic is still directed at the old endpoint k8s.gcr.io. This has not been sustainable for us as a project, as it is not utilizing the resources that have been donated to the project from other providers, and we are in the danger of running out of funds due to the cost of serving this traffic.
A redirect will enable the project to take advantage of these new resources, significantly reducing our egress bandwidth costs. We only expect this change to impact a small subset of users running in restricted environments or using very old clients that do not respect redirects properly.
What will happen to k8s.gcr.io?
Separate from the the redirect, k8s.gcr.io will be frozen and will not be updated with new images after April 3rd, 2023.
I still have questions, where should I go?
For more information on registry.k8s.io and why it was developed, see registry.k8s.io: faster, cheaper and Generally Available.
If you would like to know more about the image freeze and the last images that will be available there, see the blog post: k8s.gcr.io Image Registry Will Be Frozen From the 3rd of April 2023.
Information on the architecture of registry.k8s.io and its request handling decision tree can be found in the kubernetes/registry.k8s.io repo.
If you believe you have encountered a bug with the new registry or the redirect, please open an issue in the kubernetes/registry.k8s.io repo. Please check if there is an issue already open similar to what you are seeing before you create a new issue.
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Davanum Srinivas :: https://twitter.com/dims