Form a Standard Process of Dealing with Kubernetes Deprecations

[XinruZhang]

Currently, the most major implementation of Tekton APIs is on Kubernetes.
Kubernetes deprecates APIS ¹ now and then, we need to form a standard process
to deal with those deprecation announcements.

The benefit is obvious: we can avoid any incompatibility between Tekton and K8s
of a new version with deprecated APIs/Flags/Features removed. (#4158 wouldn't be
an issue any more).

One thing we may want to take into account is: the minimum supported k8s version
might change more often, see the reason detailed below.

---

How the minimum supported k8s version gets changed

Let's take the table below as an example, say Tekton
uses a to-be-deprecated v1beta1 K8s resource, to migrate the deprecation,
Tekton needs to at least depend on K8s X+3 release (meaning updating related
dependencies like client-go), and uses v1beta2 instead of v1beta1, and
there might be kubernetes minor version upgrade between release X and X+3.

Release	API Versions	Preferred/Storage Version	Notes
X	v1beta1	v1beta1
X+1	v1beta1	v1beta1
X+2	v1beta1	v1beta1
X+3	v1beta2, v1beta1 (deprecated)	v1beta1	v1beta1 is deprecated, "action required" relnote
X+4	v1beta2, v1beta1 (deprecated)	v1beta2
X+5	v1, v1beta1 (deprecated), v1beta2 (deprecated)	v1beta2	v1beta2 is deprecated, "action required" relnote
X+6	v1, v1beta2 (deprecated)	v1	v1beta1 is removed, "action required" relnote

Footnotes

1. https://kubernetes.io/docs/reference/using-api/deprecation-guide/ ↩

[vdemeester]

Note: we also depend on knative.dev/pkg minimun Kubernetes version. So far, the only "time" we bump our "minimun" Kubernetes verison is when we bump knative.dev/pkg and it does bump that version.

/cc @imjasonh

[tekton-robot]

Issues go stale after 90d of inactivity.
Mark the issue as fresh with /remove-lifecycle stale with a justification.
Stale issues rot after an additional 30d of inactivity and eventually close.
If this issue is safe to close now please do so with /close with a justification.
If this issue should be exempted, mark the issue as frozen with /lifecycle frozen with a justification.

/lifecycle stale

Send feedback to tektoncd/plumbing.

[tekton-robot]

Stale issues rot after 30d of inactivity.
Mark the issue as fresh with /remove-lifecycle rotten with a justification.
Rotten issues close after an additional 30d of inactivity.
If this issue is safe to close now please do so with /close with a justification.
If this issue should be exempted, mark the issue as frozen with /lifecycle frozen with a justification.

/lifecycle rotten

Send feedback to tektoncd/plumbing.

[tekton-robot]

Rotten issues close after 30d of inactivity.
Reopen the issue with /reopen with a justification.
Mark the issue as fresh with /remove-lifecycle rotten with a justification.
If this issue should be exempted, mark the issue as frozen with /lifecycle frozen with a justification.

/close

Send feedback to tektoncd/plumbing.

[tekton-robot]

@tekton-robot: Closing this issue.

In response to this:

Rotten issues close after 30d of inactivity.
Reopen the issue with /reopen with a justification.
Mark the issue as fresh with /remove-lifecycle rotten with a justification.
If this issue should be exempted, mark the issue as frozen with /lifecycle frozen with a justification.

/close

Send feedback to tektoncd/plumbing.

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.