Legacy kubelet image pull credentials mechanism not documented

[sftim]

This is a Bug Report

Problem:
Add (reinstate!) documentation for the legacy credential provider integration in the kubelet that has integrations for:

• ACR (Azure Container Registry)
• ECR (Elastic Container Registry)
• GCR (Google Container Registry)

Why is this needed:

Kubelet has a credential provider mechanism, which gives kubelet the ability to dynamically fetch credentials for image registries. Today there are three built-in implementations of the kubelet credential provider for ACR (Azure Container Registry), ECR (Elastic Container Registry), and GCR (Google Container Registry).

— https://github.com/kubernetes/enhancements/tree/master/keps/sig-node/2133-kubelet-credential-providers

That legacy mechanism exists but is not currently documented.

Additional Information:
PR #21438 removed some earlier documentation for the built-in mechanism. The removal was aimed at removing documentation for third-party integrations but (in error) also removed details of the legacy in-tree implementation.

/language en
/sig node
/sig cloud-provider

[sftim]

Any new documentation we add for this should hyperlink to https://kubernetes.io/docs/tasks/kubelet-credential-provider/kubelet-credential-provider/, and vice versa.

[SergeyKanzhelev]

/cc @adisky @andrewsykim

/triage accepted

[k8s-triage-robot]

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/lifecycle stale

[k8s-triage-robot]

The Kubernetes project currently lacks enough contributors to adequately respond to all issues and PRs.

This bot triages issues and PRs according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

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/lifecycle stale

[k8s-triage-robot]

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues and PRs.

This bot triages issues and PRs according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

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/lifecycle rotten

[sftim]

/remove-lifecycle rotten
/lifecycle stale

[k8s-triage-robot]

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues and PRs.

This bot triages issues and PRs according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Mark this issue or PR as fresh with /remove-lifecycle rotten
• Close this issue or PR with /close
• Offer to help out with Issue Triage

Please send feedback to sig-contributor-experience at kubernetes/community.

/lifecycle rotten

[sftim]

/remove-lifecycle rotten
/lifecycle stale

[sftim]

/priority important-soon

This should have landed for v1.26 (ideally: earlier)

[sftim]

I suppose that we now need to reinstate this into the v1.25 docs and document in the live docs that their was suc a mechanism previously.

[k8s-triage-robot]

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues and PRs.

This bot triages issues and PRs according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Mark this issue or PR as fresh with /remove-lifecycle rotten
• Close this issue or PR with /close
• Offer to help out with Issue Triage

Please send feedback to sig-contributor-experience at kubernetes/community.

/lifecycle rotten

[k8s-triage-robot]

The issue has been marked as an important bug and triaged.
Such issues are automatically marked as frozen when hitting the rotten state
to avoid missing important bugs.

Please send feedback to sig-contributor-experience at kubernetes/community.

/lifecycle frozen

[sftim]

We've shipped v1.26

/priority important-longterm

OK to demote further once v1.27 ships (a shame, but we just might not get round to it).

[sftim]

I'll demote it now, I think.
/remove-priority important-longterm

[sftim]

/remove-priority important-soon
/priority backlog

[sftim]

/remove-lifecycle frozen

[mrgiles]

/assign