Include stderr in cred provider plugin errors

[cartermckinnon]

What type of PR is this?

/kind feature

This is a small quality-of-life thing.

What this PR does / why we need it:

This PR includes stderr in the error returned after failing to invoke a credential provider exec plugin. Failure in these external plugins (due to mismatched apiVersion, for example) currently only results in a generic log line:

plugin.go:233] Failed getting credential from external registry credential provider: error execing credential provider plugin foo for image bar: exit status 1

After this PR, the message will include more details. For example:

plugin.go:233] Failed getting credential from external registry credential provider: error execing credential provider plugin foo for image bar: exit status 1: E0418 06:12:14.490885   14903 main.go:161] Error running credential provider plugin: group version credentialprovider.kubelet.k8s.io/v1beta1 is not supported

Determining why a credential provider plugin failed is otherwise somewhat obtuse. I've done this by placing a logging shim between kubelet and the provider, but this PR makes such an effort unnecessary.

Which issue(s) this PR fixes:

N/A

Special notes for your reviewer:

While the credential provider does return secrets via standard output, which should never be logged by kubelet -- secrets should not be logged to standard error. If we need to explicitly document this in the credential provider contract, we can do that.

Does this PR introduce a user-facing change?

External credential provider plugins now have their standard error output logged by kubelet upon failures.

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

N/A

[k8s-ci-robot]

@cartermckinnon: The label(s) kind/(?) cannot be applied, because the repository doesn't have them.

In response to this:

What type of PR is this?

/kind feature (?)

What this PR does / why we need it:

This PR includes stderr in the error returned after failing to invoke a credential provider exec plugin. Failure in these external plugins (due to mismatched apiVersion, for example) currently only results in a generic log line:

plugin.go:233] Failed getting credential from external registry credential provider: error execing credential provider plugin foo for image bar: exit status 1

After this PR, the message will include more details. For example:

plugin.go:233] Failed getting credential from external registry credential provider: error execing credential provider plugin foo for image bar: exit status 1: E0418 06:12:14.490885   14903 main.go:161] Error running credential provider plugin: group version credentialprovider.kubelet.k8s.io/v1beta1 is not supported

Which issue(s) this PR fixes:

N/A

Special notes for your reviewer:

While the credential provider does return secrets, which should not be logged by kubelet -- secrets should not be logged to standard error. If we need to explicitly document this in the credential provider contract, we can do that.

Does this PR introduce a user-facing change?

External credential provider plugins now have their standard error output logged by kubelet upon failures.

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

N/A

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[k8s-ci-robot]

Hi @cartermckinnon. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[dims]

one line fix to pass through an err, happy to land this.

/ok-to-test
/approve
/lgtm
/sig node

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: fedd000fde3c45cf031e68470e622c268d5efbbe

[dims]

/priority important-soon
/triage accepted

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cartermckinnon, dims

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• pkg/credentialprovider/OWNERS [dims]

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