Tools installation docs are not entirely true about apt repository signing key and Kubernetes version

[slabstone]

This is a Bug Report

Problem:
https://kubernetes.io/docs/tasks/tools/install-kubectl-linux/#install-using-native-package-management says

The same signing key is used for all repositories so you can disregard the version in the URL:

This is not entirely true, as the current key is only present in versions 1.28 and above, while 1.27 and below have expired key. I understand that versions below 1.27 are no longer supported, but it's likely that the same problem occurs after the current key expires on 2026-12-29, only with different version numbers.

Proposed Solution:
Rephrase the statement about signing key and Kubernetes version so it's clear that it's not the same key for all repositories, e. g. changing it to "all supported versions".

Page to Update:
https://kubernetes.io/docs/tasks/tools/install-kubectl-linux/#install-using-native-package-management

[k8s-ci-robot]

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[sftim]

What repositories are you thinking of @slabstone? I don't think there's a repository for v1.27 Kubernetes, at least not one published by the Kubernetes project.

The docs don't cover third party repositories.

[slabstone]

What repositories are you thinking of @slabstone? I don't think there's a repository for v1.27 Kubernetes, at least not one published by the Kubernetes project.

You can add repository for versions 1.24 through 1.27 using the current docs and install kubectl if you bypass apt signature verification.

Selected version '1.24.17-1.1' (isv:kubernetes:core:stable:v1.24:pkgs.k8s.io [amd64]) for 'kubectl'
...
Get:1 https://prod-cdn.packages.k8s.io/repositories/isv:/kubernetes:/core:/stable:/v1.24/deb  kubectl 1.24.17-1.1 [9543 kB]

[sftim]

AIUI we don't document that https://prod-cdn.packages.k8s.io/ works; this is an internal implementation detail. You should not rely on this.

For the documented ways to download Kubernetes, see https://kubernetes.io/releases/download/

[sftim]

/priority awaiting-more-evidence