allow exec into ingress-nginx-controll pod, when any type of sidecar is injected into the controller pod

[JacobHenner]

What this PR does / why we need it:

Add support for --container flag, which sets an explicit container name for exec operations. Defaults to controller.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• CVE Report (Scanner found CVE and adding report)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation only

Which issue/s this PR fixes

Fixes #4361
Fixes #4362
Fixes #9702

How Has This Been Tested?

Tested relevant commands against existing installation of the latest ingress-nginx, supplying valid and invalid --container {container} options, and omitting the flag entirely.

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have added unit and/or e2e tests to cover my changes.
• All new and existing tests passed.
• Added Release Notes.

Does my pull request need a release note?

Any user-visible or operator-visible change qualifies for a release note. This could be a:

• CLI change
• API change
• UI change
• configuration schema change
• behavioral change
• change in non-functional attributes such as efficiency or availability, availability of a new platform
• a warning about a deprecation
• fix of a previous Known Issue
• fix of a vulnerability (CVE)

No release notes are required for changes to the following:

• Tests
• Build infrastructure
• Fixes for unreleased bugs

For more tips on writing good release notes, check out the Release Notes Handbook

Added support for the --container flag in the kubectl plugin, which can be supplied to override the default controller container name for commands that invoke `kubectl exec`. (@jacobhenner)

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[longwuyuan]

@JacobHenner it will be a very useful & generally helpful discussion, if this really is a generic problem. And if triaged to be a problem and changes are made to make exec work in controller pod with sidecars, it could help a lot with debugging.

On the flip side though, the very fact that the ingress-nginx-controller pod is not like a frontend or a backend application pod, brings in several other considerations. Someone needs to elaborate & describe the small tiny details, with regard to the possibility of any and every possible sidecar that can be injected, including a service-mesh sidecar, and its implications on securing + hardening the controller (and maybe even mitigating perceivable problems).

The project itself is in a stabilization phase where features are not being worked on, until the project achieves the stabilization goals. Then the situation is complicated by lack of resources and the increased attention to CVEs & other security/performance related priorities. The PR history has some of that story. Then we have a almost ready implementation of OpenTelemetry for traces and the prometheus support is available since a while.

That was FYI. Please wait for other comments. Hence this is not so much as a bug, currently. When a developer engages on this and triaging is complete, more info may come out of this discussion.

/remove-kind bug
/kind feature

[k8s-ci-robot]

@longwuyuan: Those labels are not set on the issue: kind/bug

In response to this:

@JacobHenner it will be a very useful & generally helpful discussion, if this really is a generic problem. And if triaged to be a problem and changes are made to make exec work in controller pod with sidecars, it could help a lot with debugging.

On the flip side though, the very fact that the ingress-nginx-controller pod is not like a frontend or a backend application pod, brings in several other considerations. Someone needs to elaborate & describe the small tiny details, with regard to the possibility of any and every possible sidecar that can be injected, including a service-mesh sidecar, and its implications on securing + hardening the controller (and maybe even mitigating perceivable problems).

The project itself is in a stabilization phase where features are not being worked on, until the project achieves the stabilization goals. Then the situation is complicated by lack of resources and the increased attention to CVEs & other security/performance related priorities. The PR history has some of that story. Then we have a almost ready implementation of OpenTelemetry for traces and the prometheus support is available since a while.

That was FYI. Please wait for other comments. Hence this is not so much as a bug, currently. When a developer engages on this and triaging is complete, more info may come out of this discussion.

/remove-kind bug
/kind feature

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.

[longwuyuan]

/retitle allow exec into pod when any sidecar is injected into pod

[longwuyuan]

/retitle allow exec into ingress-nginx-controll pod, when any type of sidecar is injected into the controller pod

[tao12345666333]

Just a quickly review, looks good

/ok-to-test

[github-actions]

This is stale, but we won't close it automatically, just bare in mind the maintainers may be busy with other tasks and will reach your issue ASAP. If you have any question or request to prioritize this, please reach #ingress-nginx-dev on Kubernetes Slack.

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/remove-lifecycle frozen

[rikatz]

We can also use on a probably followup https://kubernetes.io/docs/reference/labels-annotations-taints/#kubectl-kubernetes-io-default-container and make the defaulting to our container more generic.

@longwuyuan maybe you want to change it on helm charts :)

/lgtm
/approve
Thanks

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JacobHenner, rikatz

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[rikatz]

/lifecycle active