Add graduation criteria

Author: ehashman

keps/sig-node/2238-liveness-probe-grace-period/README.md

@@ -14,6 +14,9 @@
 - [Design Details](#design-details)
   - [Test Plan](#test-plan)
   - [Graduation Criteria](#graduation-criteria)
+    - [Alpha](#alpha)
+    - [Beta](#beta)
+    - [Graduation](#graduation)
   - [Upgrade / Downgrade Strategy](#upgrade--downgrade-strategy)
   - [Version Skew Strategy](#version-skew-strategy)
 - [Production Readiness Review Questionnaire](#production-readiness-review-questionnaire)
@@ -33,13 +36,13 @@
 
 Items marked with (R) are required *prior to targeting to a milestone / release*.
 
-- [ ] (R) Enhancement issue in release milestone, which links to KEP dir in [kubernetes/enhancements] (not the initial KEP PR)
-- [ ] (R) KEP approvers have approved the KEP status as `implementable`
-- [ ] (R) Design details are appropriately documented
-- [ ] (R) Test plan is in place, giving consideration to SIG Architecture and SIG Testing input
-- [ ] (R) Graduation criteria is in place
-- [ ] (R) Production readiness review completed
-- [ ] (R) Production readiness review approved
+- [X] (R) Enhancement issue in release milestone, which links to KEP dir in [kubernetes/enhancements] (not the initial KEP PR)
+- [X] (R) KEP approvers have approved the KEP status as `implementable`
+- [X] (R) Design details are appropriately documented
+- [X] (R) Test plan is in place, giving consideration to SIG Architecture and SIG Testing input
+- [X] (R) Graduation criteria is in place
+- [X] (R) Production readiness review completed
+- [X] (R) Production readiness review approved
 - [ ] "Implementation History" section is up-to-date for milestone
 - [ ] User-facing documentation has been created in [kubernetes/website], for publication to [kubernetes.io]
 - [ ] Supporting documentation—e.g., additional design documents, links to mailing list discussions/SIG meetings, relevant PRs/issues, release notes
@@ -189,60 +192,21 @@ quickly.
 
 ### Graduation Criteria
 
-<!--
-**Note:** *Not required until targeted at a release.*
-
-Define graduation milestones.
-
-These may be defined in terms of API maturity, or as something else. The KEP
-should keep this high-level with a focus on what signals will be looked at to
-determine graduation.
-
-Consider the following in developing the graduation criteria for this enhancement:
-- [Maturity levels (`alpha`, `beta`, `stable`)][maturity-levels]
-- [Deprecation policy][deprecation-policy]
-
-Clearly define what graduation means by either linking to the [API doc
-definition](https://kubernetes.io/docs/concepts/overview/kubernetes-api/#api-versioning)
-or by redefining what graduation means.
-
-In general we try to use the same stages (alpha, beta, GA), regardless of how the
-functionality is accessed.
+#### Alpha
 
-[maturity-levels]: https://git.k8s.io/community/contributors/devel/sig-architecture/api_changes.md#alpha-beta-and-stable-versions
-[deprecation-policy]: https://kubernetes.io/docs/reference/using-api/deprecation-policy/
+- New probe field, `terminationGracePeriodSeconds`, is implemented and
+  available behind a feature flag.
+- Appropriate tests are written.
 
-Below are some examples to consider, in addition to the aforementioned [maturity levels][maturity-levels].
+_Below graduation criteria are tentative._
 
-#### Alpha -> Beta Graduation
+#### Beta
 
-- Gather feedback from developers and surveys
-- Complete features A, B, C
-- Tests are in Testgrid and linked in KEP
+- Feature flag is defaulted on.
 
-#### Beta -> GA Graduation
+#### Graduation
 
-- N examples of real-world usage
-- N installs
-- More rigorous forms of testing—e.g., downgrade tests and scalability tests
-- Allowing time for feedback
-
-**Note:** Generally we also wait at least two releases between beta and
-GA/stable, because there's no opportunity for user feedback, or even bug reports,
-in back-to-back releases.
-
-#### Removing a Deprecated Flag
-
-- Announce deprecation and support policy of the existing flag
-- Two versions passed since introducing the functionality that deprecates the flag (to address version skew)
-- Address feedback on usage/changed behavior, provided on GitHub issues
-- Deprecate the flag
-
-**For non-optional features moving to GA, the graduation criteria must include
-[conformance tests].**
-
-[conformance tests]: https://git.k8s.io/community/contributors/devel/sig-architecture/conformance-tests.md
--->
+- Feature flag is removed, feature is graduated.
 
 ### Upgrade / Downgrade Strategy