From 48869a61a3ae4ee901b37ca1682b56be2ae3c0be Mon Sep 17 00:00:00 2001
From: Hemant Kumar <hekumar@redhat.com>
Date: Thu, 9 Jan 2025 11:02:34 -0500
Subject: [PATCH 01/13] Add a proposal for integrating volume limits into
 cluster autoscaler

---
 .../5030-attach-limit-autoscaler/README.md    | 807 ++++++++++++++++++
 .../5030-attach-limit-autoscaler/kep.yaml     |  50 ++
 2 files changed, 857 insertions(+)
 create mode 100644 keps/sig-storage/5030-attach-limit-autoscaler/README.md
 create mode 100644 keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml

diff --git a/keps/sig-storage/5030-attach-limit-autoscaler/README.md b/keps/sig-storage/5030-attach-limit-autoscaler/README.md
new file mode 100644
index 00000000000..7018679e98f
--- /dev/null
+++ b/keps/sig-storage/5030-attach-limit-autoscaler/README.md
@@ -0,0 +1,807 @@
+<!--
+**Note:** When your KEP is complete, all of these comment blocks should be removed.
+
+To get started with this template:
+
+- [ ] **Pick a hosting SIG.**
+  Make sure that the problem space is something the SIG is interested in taking
+  up. KEPs should not be checked in without a sponsoring SIG.
+- [ ] **Create an issue in kubernetes/enhancements**
+  When filing an enhancement tracking issue, please make sure to complete all
+  fields in that template. One of the fields asks for a link to the KEP. You
+  can leave that blank until this KEP is filed, and then go back to the
+  enhancement and add the link.
+- [ ] **Make a copy of this template directory.**
+  Copy this template into the owning SIG's directory and name it
+  `NNNN-short-descriptive-title`, where `NNNN` is the issue number (with no
+  leading-zero padding) assigned to your enhancement above.
+- [ ] **Fill out as much of the kep.yaml file as you can.**
+  At minimum, you should fill in the "Title", "Authors", "Owning-sig",
+  "Status", and date-related fields.
+- [ ] **Fill out this file as best you can.**
+  At minimum, you should fill in the "Summary" and "Motivation" sections.
+  These should be easy if you've preflighted the idea of the KEP with the
+  appropriate SIG(s).
+- [ ] **Create a PR for this KEP.**
+  Assign it to people in the SIG who are sponsoring this process.
+- [ ] **Merge early and iterate.**
+  Avoid getting hung up on specific details and instead aim to get the goals of
+  the KEP clarified and merged quickly. The best way to do this is to just
+  start with the high-level sections and fill out details incrementally in
+  subsequent PRs.
+
+Just because a KEP is merged does not mean it is complete or approved. Any KEP
+marked as `provisional` is a working document and subject to change. You can
+denote sections that are under active debate as follows:
+
+```
+<<[UNRESOLVED optional short context or usernames ]>>
+Stuff that is being argued.
+<<[/UNRESOLVED]>>
+```
+
+When editing KEPS, aim for tightly-scoped, single-topic PRs to keep discussions
+focused. If you disagree with what is already in a document, open a new PR
+with suggested changes.
+
+One KEP corresponds to one "feature" or "enhancement" for its whole lifecycle.
+You do not need a new KEP to move from beta to GA, for example. If
+new details emerge that belong in the KEP, edit the KEP. Once a feature has become
+"implemented", major changes should get new KEPs.
+
+The canonical place for the latest set of instructions (and the likely source
+of this file) is [here](/keps/NNNN-kep-template/README.md).
+
+**Note:** Any PRs to move a KEP to `implementable`, or significant changes once
+it is marked `implementable`, must be approved by each of the KEP approvers.
+If none of those approvers are still appropriate, then changes to that list
+should be approved by the remaining approvers and/or the owning SIG (or
+SIG Architecture for cross-cutting KEPs).
+-->
+# KEP-NNNN: Your short, descriptive title
+
+<!--
+This is the title of your KEP. Keep it short, simple, and descriptive. A good
+title can help communicate what the KEP is and should be considered as part of
+any review.
+-->
+
+<!--
+A table of contents is helpful for quickly jumping to sections of a KEP and for
+highlighting any additional information provided beyond the standard KEP
+template.
+
+Ensure the TOC is wrapped with
+  <code>&lt;!-- toc --&rt;&lt;!-- /toc --&rt;</code>
+tags, and then generate with `hack/update-toc.sh`.
+-->
+
+<!-- toc -->
+- [Release Signoff Checklist](#release-signoff-checklist)
+- [Summary](#summary)
+- [Motivation](#motivation)
+  - [Goals](#goals)
+  - [Non-Goals](#non-goals)
+- [Proposal](#proposal)
+  - [User Stories (Optional)](#user-stories-optional)
+    - [Story 1](#story-1)
+    - [Story 2](#story-2)
+  - [Notes/Constraints/Caveats (Optional)](#notesconstraintscaveats-optional)
+  - [Risks and Mitigations](#risks-and-mitigations)
+- [Design Details](#design-details)
+  - [Test Plan](#test-plan)
+      - [Prerequisite testing updates](#prerequisite-testing-updates)
+      - [Unit tests](#unit-tests)
+      - [Integration tests](#integration-tests)
+      - [e2e tests](#e2e-tests)
+  - [Graduation Criteria](#graduation-criteria)
+  - [Upgrade / Downgrade Strategy](#upgrade--downgrade-strategy)
+  - [Version Skew Strategy](#version-skew-strategy)
+- [Production Readiness Review Questionnaire](#production-readiness-review-questionnaire)
+  - [Feature Enablement and Rollback](#feature-enablement-and-rollback)
+  - [Rollout, Upgrade and Rollback Planning](#rollout-upgrade-and-rollback-planning)
+  - [Monitoring Requirements](#monitoring-requirements)
+  - [Dependencies](#dependencies)
+  - [Scalability](#scalability)
+  - [Troubleshooting](#troubleshooting)
+- [Implementation History](#implementation-history)
+- [Drawbacks](#drawbacks)
+- [Alternatives](#alternatives)
+- [Infrastructure Needed (Optional)](#infrastructure-needed-optional)
+<!-- /toc -->
+
+## Release Signoff Checklist
+
+<!--
+**ACTION REQUIRED:** In order to merge code into a release, there must be an
+issue in [kubernetes/enhancements] referencing this KEP and targeting a release
+milestone **before the [Enhancement Freeze](https://git.k8s.io/sig-release/releases)
+of the targeted release**.
+
+For enhancements that make changes to code or processes/procedures in core
+Kubernetes—i.e., [kubernetes/kubernetes], we require the following Release
+Signoff checklist to be completed.
+
+Check these off as they are completed for the Release Team to track. These
+checklist items _must_ be updated for the enhancement to be released.
+-->
+
+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 (including test refactors)
+  - [ ] e2e Tests for all Beta API Operations (endpoints)
+  - [ ] (R) Ensure GA e2e tests meet requirements for [Conformance Tests](https://github.com/kubernetes/community/blob/master/contributors/devel/sig-architecture/conformance-tests.md) 
+  - [ ] (R) Minimum Two Week Window for GA e2e tests to prove flake free
+- [ ] (R) Graduation criteria is in place
+  - [ ] (R) [all GA Endpoints](https://github.com/kubernetes/community/pull/1806) must be hit by [Conformance Tests](https://github.com/kubernetes/community/blob/master/contributors/devel/sig-architecture/conformance-tests.md) 
+- [ ] (R) Production readiness review completed
+- [ ] (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
+
+<!--
+**Note:** This checklist is iterative and should be reviewed and updated every time this enhancement is being considered for a milestone.
+-->
+
+[kubernetes.io]: https://kubernetes.io/
+[kubernetes/enhancements]: https://git.k8s.io/enhancements
+[kubernetes/kubernetes]: https://git.k8s.io/kubernetes
+[kubernetes/website]: https://git.k8s.io/website
+
+## Summary
+
+<!--
+This section is incredibly important for producing high-quality, user-focused
+documentation such as release notes or a development roadmap. It should be
+possible to collect this information before implementation begins, in order to
+avoid requiring implementors to split their attention between writing release
+notes and implementing the feature itself. KEP editors and SIG Docs
+should help to ensure that the tone and content of the `Summary` section is
+useful for a wide audience.
+
+A good summary is probably at least a paragraph in length.
+
+Both in this section and below, follow the guidelines of the [documentation
+style guide]. In particular, wrap lines to a reasonable length, to make it
+easier for reviewers to cite specific portions, and to minimize diff churn on
+updates.
+
+[documentation style guide]: https://github.com/kubernetes/community/blob/master/contributors/guide/style-guide.md
+-->
+
+## Motivation
+
+<!--
+This section is for explicitly listing the motivation, goals, and non-goals of
+this KEP.  Describe why the change is important and the benefits to users. The
+motivation section can optionally provide links to [experience reports] to
+demonstrate the interest in a KEP within the wider Kubernetes community.
+
+[experience reports]: https://github.com/golang/go/wiki/ExperienceReports
+-->
+
+### Goals
+
+<!--
+List the specific goals of the KEP. What is it trying to achieve? How will we
+know that this has succeeded?
+-->
+
+### Non-Goals
+
+<!--
+What is out of scope for this KEP? Listing non-goals helps to focus discussion
+and make progress.
+-->
+
+## Proposal
+
+<!--
+This is where we get down to the specifics of what the proposal actually is.
+This should have enough detail that reviewers can understand exactly what
+you're proposing, but should not include things like API designs or
+implementation. What is the desired outcome and how do we measure success?.
+The "Design Details" section below is for the real
+nitty-gritty.
+-->
+
+### User Stories (Optional)
+
+<!--
+Detail the things that people will be able to do if this KEP is implemented.
+Include as much detail as possible so that people can understand the "how" of
+the system. The goal here is to make this feel real for users without getting
+bogged down.
+-->
+
+#### Story 1
+
+#### Story 2
+
+### Notes/Constraints/Caveats (Optional)
+
+<!--
+What are the caveats to the proposal?
+What are some important details that didn't come across above?
+Go in to as much detail as necessary here.
+This might be a good place to talk about core concepts and how they relate.
+-->
+
+### Risks and Mitigations
+
+<!--
+What are the risks of this proposal, and how do we mitigate? Think broadly.
+For example, consider both security and how this will impact the larger
+Kubernetes ecosystem.
+
+How will security be reviewed, and by whom?
+
+How will UX be reviewed, and by whom?
+
+Consider including folks who also work outside the SIG or subproject.
+-->
+
+## Design Details
+
+<!--
+This section should contain enough information that the specifics of your
+change are understandable. This may include API specs (though not always
+required) or even code snippets. If there's any ambiguity about HOW your
+proposal will be implemented, this is the place to discuss them.
+-->
+
+### Test Plan
+
+<!--
+**Note:** *Not required until targeted at a release.*
+The goal is to ensure that we don't accept enhancements with inadequate testing.
+
+All code is expected to have adequate tests (eventually with coverage
+expectations). Please adhere to the [Kubernetes testing guidelines][testing-guidelines]
+when drafting this test plan.
+
+[testing-guidelines]: https://git.k8s.io/community/contributors/devel/sig-testing/testing.md
+-->
+
+[ ] I/we understand the owners of the involved components may require updates to
+existing tests to make this code solid enough prior to committing the changes necessary
+to implement this enhancement.
+
+##### Prerequisite testing updates
+
+<!--
+Based on reviewers feedback describe what additional tests need to be added prior
+implementing this enhancement to ensure the enhancements have also solid foundations.
+-->
+
+##### Unit tests
+
+<!--
+In principle every added code should have complete unit test coverage, so providing
+the exact set of tests will not bring additional value.
+However, if complete unit test coverage is not possible, explain the reason of it
+together with explanation why this is acceptable.
+-->
+
+<!--
+Additionally, for Alpha try to enumerate the core package you will be touching
+to implement this enhancement and provide the current unit coverage for those
+in the form of:
+- <package>: <date> - <current test coverage>
+The data can be easily read from:
+https://testgrid.k8s.io/sig-testing-canaries#ci-kubernetes-coverage-unit
+
+This can inform certain test coverage improvements that we want to do before
+extending the production code to implement this enhancement.
+-->
+
+- `<package>`: `<date>` - `<test coverage>`
+
+##### Integration tests
+
+<!--
+Integration tests are contained in k8s.io/kubernetes/test/integration.
+Integration tests allow control of the configuration parameters used to start the binaries under test.
+This is different from e2e tests which do not allow configuration of parameters.
+Doing this allows testing non-default options and multiple different and potentially conflicting command line options.
+-->
+
+<!--
+This question should be filled when targeting a release.
+For Alpha, describe what tests will be added to ensure proper quality of the enhancement.
+
+For Beta and GA, add links to added tests together with links to k8s-triage for those tests:
+https://storage.googleapis.com/k8s-triage/index.html
+-->
+
+- <test>: <link to test coverage>
+
+##### e2e tests
+
+<!--
+This question should be filled when targeting a release.
+For Alpha, describe what tests will be added to ensure proper quality of the enhancement.
+
+For Beta and GA, add links to added tests together with links to k8s-triage for those tests:
+https://storage.googleapis.com/k8s-triage/index.html
+
+We expect no non-infra related flakes in the last month as a GA graduation criteria.
+-->
+
+- <test>: <link to test coverage>
+
+### Graduation Criteria
+
+<!--
+**Note:** *Not required until targeted at a release.*
+
+Define graduation milestones.
+
+These may be defined in terms of API maturity, [feature gate] graduations, 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]
+- [Feature gate][feature gate] lifecycle
+- [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.
+
+[feature gate]: https://git.k8s.io/community/contributors/devel/sig-architecture/feature-gates.md
+[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/
+
+Below are some examples to consider, in addition to the aforementioned [maturity levels][maturity-levels].
+
+#### Alpha
+
+- Feature implemented behind a feature flag
+- Initial e2e tests completed and enabled
+
+#### Beta
+
+- Gather feedback from developers and surveys
+- Complete features A, B, C
+- Additional tests are in Testgrid and linked in KEP
+
+#### GA
+
+- 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.
+
+**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
+
+#### Deprecation
+
+- 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
+-->
+
+### Upgrade / Downgrade Strategy
+
+<!--
+If applicable, how will the component be upgraded and downgraded? Make sure
+this is in the test plan.
+
+Consider the following in developing an upgrade/downgrade strategy for this
+enhancement:
+- What changes (in invocations, configurations, API use, etc.) is an existing
+  cluster required to make on upgrade, in order to maintain previous behavior?
+- What changes (in invocations, configurations, API use, etc.) is an existing
+  cluster required to make on upgrade, in order to make use of the enhancement?
+-->
+
+### Version Skew Strategy
+
+<!--
+If applicable, how will the component handle version skew with other
+components? What are the guarantees? Make sure this is in the test plan.
+
+Consider the following in developing a version skew strategy for this
+enhancement:
+- Does this enhancement involve coordinating behavior in the control plane and nodes?
+- How does an n-3 kubelet or kube-proxy without this feature available behave when this feature is used?
+- How does an n-1 kube-controller-manager or kube-scheduler without this feature available behave when this feature is used?
+- Will any other components on the node change? For example, changes to CSI,
+  CRI or CNI may require updating that component before the kubelet.
+-->
+
+## Production Readiness Review Questionnaire
+
+<!--
+
+Production readiness reviews are intended to ensure that features merging into
+Kubernetes are observable, scalable and supportable; can be safely operated in
+production environments, and can be disabled or rolled back in the event they
+cause increased failures in production. See more in the PRR KEP at
+https://git.k8s.io/enhancements/keps/sig-architecture/1194-prod-readiness.
+
+The production readiness review questionnaire must be completed and approved
+for the KEP to move to `implementable` status and be included in the release.
+
+In some cases, the questions below should also have answers in `kep.yaml`. This
+is to enable automation to verify the presence of the review, and to reduce review
+burden and latency.
+
+The KEP must have a approver from the
+[`prod-readiness-approvers`](http://git.k8s.io/enhancements/OWNERS_ALIASES)
+team. Please reach out on the
+[#prod-readiness](https://kubernetes.slack.com/archives/CPNHUMN74) channel if
+you need any help or guidance.
+-->
+
+### Feature Enablement and Rollback
+
+<!--
+This section must be completed when targeting alpha to a release.
+-->
+
+###### How can this feature be enabled / disabled in a live cluster?
+
+<!--
+Pick one of these and delete the rest.
+
+Documentation is available on [feature gate lifecycle] and expectations, as
+well as the [existing list] of feature gates.
+
+[feature gate lifecycle]: https://git.k8s.io/community/contributors/devel/sig-architecture/feature-gates.md
+[existing list]: https://kubernetes.io/docs/reference/command-line-tools-reference/feature-gates/
+-->
+
+- [ ] Feature gate (also fill in values in `kep.yaml`)
+  - Feature gate name:
+  - Components depending on the feature gate:
+- [ ] Other
+  - Describe the mechanism:
+  - Will enabling / disabling the feature require downtime of the control
+    plane?
+  - Will enabling / disabling the feature require downtime or reprovisioning
+    of a node?
+
+###### Does enabling the feature change any default behavior?
+
+<!--
+Any change of default behavior may be surprising to users or break existing
+automations, so be extremely careful here.
+-->
+
+###### Can the feature be disabled once it has been enabled (i.e. can we roll back the enablement)?
+
+<!--
+Describe the consequences on existing workloads (e.g., if this is a runtime
+feature, can it break the existing applications?).
+
+Feature gates are typically disabled by setting the flag to `false` and
+restarting the component. No other changes should be necessary to disable the
+feature.
+
+NOTE: Also set `disable-supported` to `true` or `false` in `kep.yaml`.
+-->
+
+###### What happens if we reenable the feature if it was previously rolled back?
+
+###### Are there any tests for feature enablement/disablement?
+
+<!--
+The e2e framework does not currently support enabling or disabling feature
+gates. However, unit tests in each component dealing with managing data, created
+with and without the feature, are necessary. At the very least, think about
+conversion tests if API types are being modified.
+
+Additionally, for features that are introducing a new API field, unit tests that
+are exercising the `switch` of feature gate itself (what happens if I disable a
+feature gate after having objects written with the new field) are also critical.
+You can take a look at one potential example of such test in:
+https://github.com/kubernetes/kubernetes/pull/97058/files#diff-7826f7adbc1996a05ab52e3f5f02429e94b68ce6bce0dc534d1be636154fded3R246-R282
+-->
+
+### Rollout, Upgrade and Rollback Planning
+
+<!--
+This section must be completed when targeting beta to a release.
+-->
+
+###### How can a rollout or rollback fail? Can it impact already running workloads?
+
+<!--
+Try to be as paranoid as possible - e.g., what if some components will restart
+mid-rollout?
+
+Be sure to consider highly-available clusters, where, for example,
+feature flags will be enabled on some API servers and not others during the
+rollout. Similarly, consider large clusters and how enablement/disablement
+will rollout across nodes.
+-->
+
+###### What specific metrics should inform a rollback?
+
+<!--
+What signals should users be paying attention to when the feature is young
+that might indicate a serious problem?
+-->
+
+###### Were upgrade and rollback tested? Was the upgrade->downgrade->upgrade path tested?
+
+<!--
+Describe manual testing that was done and the outcomes.
+Longer term, we may want to require automated upgrade/rollback tests, but we
+are missing a bunch of machinery and tooling and can't do that now.
+-->
+
+###### Is the rollout accompanied by any deprecations and/or removals of features, APIs, fields of API types, flags, etc.?
+
+<!--
+Even if applying deprecation policies, they may still surprise some users.
+-->
+
+### Monitoring Requirements
+
+<!--
+This section must be completed when targeting beta to a release.
+
+For GA, this section is required: approvers should be able to confirm the
+previous answers based on experience in the field.
+-->
+
+###### How can an operator determine if the feature is in use by workloads?
+
+<!--
+Ideally, this should be a metric. Operations against the Kubernetes API (e.g.,
+checking if there are objects with field X set) may be a last resort. Avoid
+logs or events for this purpose.
+-->
+
+###### How can someone using this feature know that it is working for their instance?
+
+<!--
+For instance, if this is a pod-related feature, it should be possible to determine if the feature is functioning properly
+for each individual pod.
+Pick one more of these and delete the rest.
+Please describe all items visible to end users below with sufficient detail so that they can verify correct enablement
+and operation of this feature.
+Recall that end users cannot usually observe component logs or access metrics.
+-->
+
+- [ ] Events
+  - Event Reason: 
+- [ ] API .status
+  - Condition name: 
+  - Other field: 
+- [ ] Other (treat as last resort)
+  - Details:
+
+###### What are the reasonable SLOs (Service Level Objectives) for the enhancement?
+
+<!--
+This is your opportunity to define what "normal" quality of service looks like
+for a feature.
+
+It's impossible to provide comprehensive guidance, but at the very
+high level (needs more precise definitions) those may be things like:
+  - per-day percentage of API calls finishing with 5XX errors <= 1%
+  - 99% percentile over day of absolute value from (job creation time minus expected
+    job creation time) for cron job <= 10%
+  - 99.9% of /health requests per day finish with 200 code
+
+These goals will help you determine what you need to measure (SLIs) in the next
+question.
+-->
+
+###### What are the SLIs (Service Level Indicators) an operator can use to determine the health of the service?
+
+<!--
+Pick one more of these and delete the rest.
+-->
+
+- [ ] Metrics
+  - Metric name:
+  - [Optional] Aggregation method:
+  - Components exposing the metric:
+- [ ] Other (treat as last resort)
+  - Details:
+
+###### Are there any missing metrics that would be useful to have to improve observability of this feature?
+
+<!--
+Describe the metrics themselves and the reasons why they weren't added (e.g., cost,
+implementation difficulties, etc.).
+-->
+
+### Dependencies
+
+<!--
+This section must be completed when targeting beta to a release.
+-->
+
+###### Does this feature depend on any specific services running in the cluster?
+
+<!--
+Think about both cluster-level services (e.g. metrics-server) as well
+as node-level agents (e.g. specific version of CRI). Focus on external or
+optional services that are needed. For example, if this feature depends on
+a cloud provider API, or upon an external software-defined storage or network
+control plane.
+
+For each of these, fill in the following—thinking about running existing user workloads
+and creating new ones, as well as about cluster-level services (e.g. DNS):
+  - [Dependency name]
+    - Usage description:
+      - Impact of its outage on the feature:
+      - Impact of its degraded performance or high-error rates on the feature:
+-->
+
+### Scalability
+
+<!--
+For alpha, this section is encouraged: reviewers should consider these questions
+and attempt to answer them.
+
+For beta, this section is required: reviewers must answer these questions.
+
+For GA, this section is required: approvers should be able to confirm the
+previous answers based on experience in the field.
+-->
+
+###### Will enabling / using this feature result in any new API calls?
+
+<!--
+Describe them, providing:
+  - API call type (e.g. PATCH pods)
+  - estimated throughput
+  - originating component(s) (e.g. Kubelet, Feature-X-controller)
+Focusing mostly on:
+  - components listing and/or watching resources they didn't before
+  - API calls that may be triggered by changes of some Kubernetes resources
+    (e.g. update of object X triggers new updates of object Y)
+  - periodic API calls to reconcile state (e.g. periodic fetching state,
+    heartbeats, leader election, etc.)
+-->
+
+###### Will enabling / using this feature result in introducing new API types?
+
+<!--
+Describe them, providing:
+  - API type
+  - Supported number of objects per cluster
+  - Supported number of objects per namespace (for namespace-scoped objects)
+-->
+
+###### Will enabling / using this feature result in any new calls to the cloud provider?
+
+<!--
+Describe them, providing:
+  - Which API(s):
+  - Estimated increase:
+-->
+
+###### Will enabling / using this feature result in increasing size or count of the existing API objects?
+
+<!--
+Describe them, providing:
+  - API type(s):
+  - Estimated increase in size: (e.g., new annotation of size 32B)
+  - Estimated amount of new objects: (e.g., new Object X for every existing Pod)
+-->
+
+###### Will enabling / using this feature result in increasing time taken by any operations covered by existing SLIs/SLOs?
+
+<!--
+Look at the [existing SLIs/SLOs].
+
+Think about adding additional work or introducing new steps in between
+(e.g. need to do X to start a container), etc. Please describe the details.
+
+[existing SLIs/SLOs]: https://git.k8s.io/community/sig-scalability/slos/slos.md#kubernetes-slisslos
+-->
+
+###### Will enabling / using this feature result in non-negligible increase of resource usage (CPU, RAM, disk, IO, ...) in any components?
+
+<!--
+Things to keep in mind include: additional in-memory state, additional
+non-trivial computations, excessive access to disks (including increased log
+volume), significant amount of data sent and/or received over network, etc.
+This through this both in small and large cases, again with respect to the
+[supported limits].
+
+[supported limits]: https://git.k8s.io/community//sig-scalability/configs-and-limits/thresholds.md
+-->
+
+###### Can enabling / using this feature result in resource exhaustion of some node resources (PIDs, sockets, inodes, etc.)?
+
+<!--
+Focus not just on happy cases, but primarily on more pathological cases
+(e.g. probes taking a minute instead of milliseconds, failed pods consuming resources, etc.).
+If any of the resources can be exhausted, how this is mitigated with the existing limits
+(e.g. pods per node) or new limits added by this KEP?
+
+Are there any tests that were run/should be run to understand performance characteristics better
+and validate the declared limits?
+-->
+
+### Troubleshooting
+
+<!--
+This section must be completed when targeting beta to a release.
+
+For GA, this section is required: approvers should be able to confirm the
+previous answers based on experience in the field.
+
+The Troubleshooting section currently serves the `Playbook` role. We may consider
+splitting it into a dedicated `Playbook` document (potentially with some monitoring
+details). For now, we leave it here.
+-->
+
+###### How does this feature react if the API server and/or etcd is unavailable?
+
+###### What are other known failure modes?
+
+<!--
+For each of them, fill in the following information by copying the below template:
+  - [Failure mode brief description]
+    - Detection: How can it be detected via metrics? Stated another way:
+      how can an operator troubleshoot without logging into a master or worker node?
+    - Mitigations: What can be done to stop the bleeding, especially for already
+      running user workloads?
+    - Diagnostics: What are the useful log messages and their required logging
+      levels that could help debug the issue?
+      Not required until feature graduated to beta.
+    - Testing: Are there any tests for failure mode? If not, describe why.
+-->
+
+###### What steps should be taken if SLOs are not being met to determine the problem?
+
+## Implementation History
+
+<!--
+Major milestones in the lifecycle of a KEP should be tracked in this section.
+Major milestones might include:
+- the `Summary` and `Motivation` sections being merged, signaling SIG acceptance
+- the `Proposal` section being merged, signaling agreement on a proposed design
+- the date implementation started
+- the first Kubernetes release where an initial version of the KEP was available
+- the version of Kubernetes where the KEP graduated to general availability
+- when the KEP was retired or superseded
+-->
+
+## Drawbacks
+
+<!--
+Why should this KEP _not_ be implemented?
+-->
+
+## Alternatives
+
+<!--
+What other approaches did you consider, and why did you rule them out? These do
+not need to be as detailed as the proposal, but should include enough
+information to express the idea and why it was not acceptable.
+-->
+
+## Infrastructure Needed (Optional)
+
+<!--
+Use this section if you need things from the project/SIG. Examples include a
+new subproject, repos requested, or GitHub details. Listing these here allows a
+SIG to get the process for these resources started right away.
+-->
diff --git a/keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml b/keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml
new file mode 100644
index 00000000000..49fbc9d9d02
--- /dev/null
+++ b/keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml
@@ -0,0 +1,50 @@
+title: Integrate CSI Volume attach limits with cluster autoscaler
+kep-number: 5030
+authors:
+  - "@gnufied"
+owning-sig: sig-storage
+participating-sigs:
+  - sig-storage
+  - sig-scheduling
+  - sig-autoscaling
+status: provisional
+creation-date: 2025-01-09
+reviewers:
+  - TBD
+  - "@jsafrane"
+  - "@msau42"
+approvers:
+  - TBD
+
+see-also:
+  - "/keps/sig-aaa/1234-we-heard-you-like-keps"
+  - "/keps/sig-bbb/2345-everyone-gets-a-kep"
+replaces:
+  - "/keps/sig-ccc/3456-replaced-kep"
+
+# The target maturity stage in the current dev cycle for this KEP.
+stage: alpha|beta|stable
+
+# The most recent milestone for which work toward delivery of this KEP has been
+# done. This can be the current (upcoming) milestone, if it is being actively
+# worked on.
+latest-milestone: "v1.33"
+
+# The milestone at which this feature was, or is targeted to be, at each stage.
+milestone:
+  alpha: "v1.33"
+  beta: "v1.35"
+  stable: "v1.37"
+
+# The following PRR answers are required at alpha release
+# List the feature gate name and the components for which it must be enabled
+feature-gates:
+  - name: MyFeature
+    components:
+      - kube-apiserver
+      - kube-controller-manager
+disable-supported: true
+
+# The following PRR answers are required at beta release
+metrics:
+  - my_feature_metric

From 0c63a15bc7b3f5ed122a3c575565a032ec26b5e5 Mon Sep 17 00:00:00 2001
From: Hemant Kumar <hekumar@redhat.com>
Date: Tue, 10 Jun 2025 14:25:53 -0400
Subject: [PATCH 02/13] Add  PRR sections for code

---
 .../5030-attach-limit-autoscaler/README.md    | 310 +++++++-----------
 1 file changed, 110 insertions(+), 200 deletions(-)

diff --git a/keps/sig-storage/5030-attach-limit-autoscaler/README.md b/keps/sig-storage/5030-attach-limit-autoscaler/README.md
index 7018679e98f..c93fa94cda6 100644
--- a/keps/sig-storage/5030-attach-limit-autoscaler/README.md
+++ b/keps/sig-storage/5030-attach-limit-autoscaler/README.md
@@ -1,64 +1,4 @@
-<!--
-**Note:** When your KEP is complete, all of these comment blocks should be removed.
-
-To get started with this template:
-
-- [ ] **Pick a hosting SIG.**
-  Make sure that the problem space is something the SIG is interested in taking
-  up. KEPs should not be checked in without a sponsoring SIG.
-- [ ] **Create an issue in kubernetes/enhancements**
-  When filing an enhancement tracking issue, please make sure to complete all
-  fields in that template. One of the fields asks for a link to the KEP. You
-  can leave that blank until this KEP is filed, and then go back to the
-  enhancement and add the link.
-- [ ] **Make a copy of this template directory.**
-  Copy this template into the owning SIG's directory and name it
-  `NNNN-short-descriptive-title`, where `NNNN` is the issue number (with no
-  leading-zero padding) assigned to your enhancement above.
-- [ ] **Fill out as much of the kep.yaml file as you can.**
-  At minimum, you should fill in the "Title", "Authors", "Owning-sig",
-  "Status", and date-related fields.
-- [ ] **Fill out this file as best you can.**
-  At minimum, you should fill in the "Summary" and "Motivation" sections.
-  These should be easy if you've preflighted the idea of the KEP with the
-  appropriate SIG(s).
-- [ ] **Create a PR for this KEP.**
-  Assign it to people in the SIG who are sponsoring this process.
-- [ ] **Merge early and iterate.**
-  Avoid getting hung up on specific details and instead aim to get the goals of
-  the KEP clarified and merged quickly. The best way to do this is to just
-  start with the high-level sections and fill out details incrementally in
-  subsequent PRs.
-
-Just because a KEP is merged does not mean it is complete or approved. Any KEP
-marked as `provisional` is a working document and subject to change. You can
-denote sections that are under active debate as follows:
-
-```
-<<[UNRESOLVED optional short context or usernames ]>>
-Stuff that is being argued.
-<<[/UNRESOLVED]>>
-```
-
-When editing KEPS, aim for tightly-scoped, single-topic PRs to keep discussions
-focused. If you disagree with what is already in a document, open a new PR
-with suggested changes.
-
-One KEP corresponds to one "feature" or "enhancement" for its whole lifecycle.
-You do not need a new KEP to move from beta to GA, for example. If
-new details emerge that belong in the KEP, edit the KEP. Once a feature has become
-"implemented", major changes should get new KEPs.
-
-The canonical place for the latest set of instructions (and the likely source
-of this file) is [here](/keps/NNNN-kep-template/README.md).
-
-**Note:** Any PRs to move a KEP to `implementable`, or significant changes once
-it is marked `implementable`, must be approved by each of the KEP approvers.
-If none of those approvers are still appropriate, then changes to that list
-should be approved by the remaining approvers and/or the owning SIG (or
-SIG Architecture for cross-cutting KEPs).
--->
-# KEP-NNNN: Your short, descriptive title
+# KEP-5030: Integrate Volume Attach limit into cluster autoscaler
 
 <!--
 This is the title of your KEP. Keep it short, simple, and descriptive. A good
@@ -89,12 +29,17 @@ tags, and then generate with `hack/update-toc.sh`.
   - [Notes/Constraints/Caveats (Optional)](#notesconstraintscaveats-optional)
   - [Risks and Mitigations](#risks-and-mitigations)
 - [Design Details](#design-details)
+- [Cluster Autoscaler changes](#cluster-autoscaler-changes)
+  - [Scaling a node-group that already has one or more nodes.](#scaling-a-node-group-that-already-has-one-or-more-nodes)
+  - [Scaling from zero](#scaling-from-zero)
+- [Kubernetes Scheduler change](#kubernetes-scheduler-change)
   - [Test Plan](#test-plan)
       - [Prerequisite testing updates](#prerequisite-testing-updates)
       - [Unit tests](#unit-tests)
       - [Integration tests](#integration-tests)
       - [e2e tests](#e2e-tests)
   - [Graduation Criteria](#graduation-criteria)
+    - [Alpha](#alpha)
   - [Upgrade / Downgrade Strategy](#upgrade--downgrade-strategy)
   - [Version Skew Strategy](#version-skew-strategy)
 - [Production Readiness Review Questionnaire](#production-readiness-review-questionnaire)
@@ -154,82 +99,52 @@ Items marked with (R) are required *prior to targeting to a milestone / release*
 
 ## Summary
 
-<!--
-This section is incredibly important for producing high-quality, user-focused
-documentation such as release notes or a development roadmap. It should be
-possible to collect this information before implementation begins, in order to
-avoid requiring implementors to split their attention between writing release
-notes and implementing the feature itself. KEP editors and SIG Docs
-should help to ensure that the tone and content of the `Summary` section is
-useful for a wide audience.
+As part of this KEP we are proposing that, tools like cluster-autoscaler are aware of number of volumes that can be attached to a node.
 
-A good summary is probably at least a paragraph in length.
 
-Both in this section and below, follow the guidelines of the [documentation
-style guide]. In particular, wrap lines to a reasonable length, to make it
-easier for reviewers to cite specific portions, and to minimize diff churn on
-updates.
+## Motivation
 
-[documentation style guide]: https://github.com/kubernetes/community/blob/master/contributors/guide/style-guide.md
--->
+Currently cluster-autoscaler doesn’t take into account, volume-attach limit that a node may have when scaling nodes to support unschedulable pods.
 
-## Motivation
+This leads to bunch of problems:
+- If there are unschedulable pods that require more volume than one supported by newly created nodes, there will still be unschedulable pods left.
 
-<!--
-This section is for explicitly listing the motivation, goals, and non-goals of
-this KEP.  Describe why the change is important and the benefits to users. The
-motivation section can optionally provide links to [experience reports] to
-demonstrate the interest in a KEP within the wider Kubernetes community.
+- Since a node does not come up with a CSI driver typically, usually too many pods get scheduled on a node, which may not be supportable by the node in the first place. This leads to bunch of pods, just stuck.
 
-[experience reports]: https://github.com/golang/go/wiki/ExperienceReports
--->
+Once cluster-autoscaler is aware of CSI volume attach limits, we can fix kubernete's builtin scheduler to not schedule pods to nodes that don't have CSI driver installed.
 
 ### Goals
 
-<!--
-List the specific goals of the KEP. What is it trying to achieve? How will we
-know that this has succeeded?
--->
+- Modify cluster-autoscaler so as it is aware of CSI volume limits.
+- Fix scheduler, so as it doesn't schedule pods to a node that doesn't have CSI driver installed.
 
 ### Non-Goals
 
-<!--
-What is out of scope for this KEP? Listing non-goals helps to focus discussion
-and make progress.
--->
+- Deschedule pods that can't fit a node because of race conditions.
 
 ## Proposal
 
-<!--
-This is where we get down to the specifics of what the proposal actually is.
-This should have enough detail that reviewers can understand exactly what
-you're proposing, but should not include things like API designs or
-implementation. What is the desired outcome and how do we measure success?.
-The "Design Details" section below is for the real
-nitty-gritty.
--->
+As part of this proposal we are proposing changes into both cluster-autoscaler and kubernetes's built-in scheduler.
 
-### User Stories (Optional)
+1. Fix cluster-autoscaler so as it takes into account attach limits when scaling nodes from 0 in a nodegroup.
+2. Fix cluster-autoscaler so as it takes into account attach limits when scaling nodegroups with existing nodes.
+3. Fix kubernetes built-in scheduler so as we do not schedule pods to nodes that doesn't have CSI driver installed.
 
-<!--
-Detail the things that people will be able to do if this KEP is implemented.
-Include as much detail as possible so that people can understand the "how" of
-the system. The goal here is to make this feel real for users without getting
-bogged down.
--->
+
+### User Stories (Optional)
 
 #### Story 1
+- User has more than one pod that is pending because no existing node has any attach limit left.
+- Cluster autoscaler evaluates existing nodegroups.
+- It picks a nodegroup based on existing critireas and it accurately determines number of nodes it needs to spin up based on volumes that pending pods require.
 
 #### Story 2
+- A Kubernetes admin has one or more node where CSI driver is not installed. 
+- Without explicitly tainting the node or using node affinity in worklods, nodes which don't have CSI driver installed aren't used for scheduling pods that require volume.
 
 ### Notes/Constraints/Caveats (Optional)
 
-<!--
-What are the caveats to the proposal?
-What are some important details that didn't come across above?
-Go in to as much detail as necessary here.
-This might be a good place to talk about core concepts and how they relate.
--->
+Scheduler changes can only be merged after cluster-autoscaler changes has been GAed and there are no concerns about scheduler changes.
 
 ### Risks and Mitigations
 
@@ -247,12 +162,70 @@ Consider including folks who also work outside the SIG or subproject.
 
 ## Design Details
 
-<!--
-This section should contain enough information that the specifics of your
-change are understandable. This may include API specs (though not always
-required) or even code snippets. If there's any ambiguity about HOW your
-proposal will be implemented, this is the place to discuss them.
--->
+## Cluster Autoscaler changes
+
+We can split the implementation in cluster-autoscaler in two parts:
+- Scaling a node-group that already has one or more nodes.
+- Scaling a node-group that doesn’t have one or more nodes (Scaling from zero).
+
+### Scaling a node-group that already has one or more nodes.
+
+1. We propose a similar label as GPULabel added to the node that is supposed to come up with a CSI driver. This would ensure that, nodes which are supposed to have a certain CSI driver installed aren’t considered ready - https://github.com/kubernetes/autoscaler/blob/master/cluster-autoscaler/core/static_autoscaler.go#L979 until CSI driver is installed there.
+
+However, we also propose that a node will be considered ready as soon as corresponding CSI driver is being reported as installed via corresponding CSINode object.
+
+A node which is ready  but does not have CSI driver installed within certain time limit will be considered as NotReady and removed from the cluster.
+
+
+2. We propose that, we add volume limits and installed CSI driver information to framework.NodeInfo objects. So -
+
+```
+type NodeInfo struct {
+....
+....
+csiDrivers map[string]*DriverAllocatable
+..
+}
+
+type DriverAllocatable struct {
+    Allocatable int32
+}
+```
+
+3. We propose that, when saving `ClusterState` , we capture and add `csiDrivers` information to all existing nodes.
+
+4. We propose that, when getting nodeInfosForGroups , the return nodeInfo map also contains csidriver information, which can be used later on for scheduling decisions.
+
+```
+nodeInfosForGroups, autoscalerError := a.processors.TemplateNodeInfoProvider.Process(autoscalingContext, readyNodes, daemonsets, a.taintConfig, currentTime)
+```
+
+Please note that, we will have to handle the case of scaling from 0, separately from
+scaling from 1, because in former case - no CSI volume limit information will be available
+If no node exists in a NodeGroup.
+
+5. We propose that, when deciding pods that should be considered for scaling nodes in podListProcessor.Process function, we update the hinting_simulator to consider CSI volume limits of existing nodes. This will allow cluster-autoscaler to exactly know, if all unschedulable pods will fit in the recently spun or currently running nodes.
+
+Making aforementioned changes should allow us to handle scaling of nodes from 1.
+
+### Scaling from zero
+
+Scaling from zero should work similar to scaling from 1, but the main problem is - we do not have NodeInfo which can tell us what would be the CSI attach limit on the node which is being spun up in a NodeGroup.
+
+We propose that we introduce similar annotation as CPU, Memory resources in cluster-api to process attach limits available on a node.
+
+We have to introduce similar mechanism in various cloudproviders which return Template objects to incorporate volume limits. This will allow us to handle the case of scaling from zero.
+
+
+## Kubernetes Scheduler change
+
+We also propose that, if given node is not reporting any installed CSI drivers, we do not schedule pods that need CSI volumes to that node.
+
+The proposed change is small and a draft PR is available here - https://github.com/kubernetes/kubernetes/pull/130702
+
+This will stop too many pods crowding a node, when a new node is spun up and node is not yet reporting volume limits.
+
+But this alone is not enough to fix the underlying problem. Cluster-autoscaler must be fixed so as it is aware of attach limits of a node via CSINode object.
 
 ### Test Plan
 
@@ -299,75 +272,26 @@ This can inform certain test coverage improvements that we want to do before
 extending the production code to implement this enhancement.
 -->
 
-- `<package>`: `<date>` - `<test coverage>`
+- k8s.io/autoscaler/cluster-autoscaler/core: 06/10/2025 - 77.3%
 
 ##### Integration tests
 
-<!--
-Integration tests are contained in k8s.io/kubernetes/test/integration.
-Integration tests allow control of the configuration parameters used to start the binaries under test.
-This is different from e2e tests which do not allow configuration of parameters.
-Doing this allows testing non-default options and multiple different and potentially conflicting command line options.
--->
-
-<!--
-This question should be filled when targeting a release.
-For Alpha, describe what tests will be added to ensure proper quality of the enhancement.
-
-For Beta and GA, add links to added tests together with links to k8s-triage for those tests:
-https://storage.googleapis.com/k8s-triage/index.html
--->
-
-- <test>: <link to test coverage>
+None
 
 ##### e2e tests
 
-<!--
-This question should be filled when targeting a release.
-For Alpha, describe what tests will be added to ensure proper quality of the enhancement.
-
-For Beta and GA, add links to added tests together with links to k8s-triage for those tests:
-https://storage.googleapis.com/k8s-triage/index.html
+We are planning to add e2e tests that verify behaviour of cluster autoscaler when it scales nodes for pods that require volumes.
 
-We expect no non-infra related flakes in the last month as a GA graduation criteria.
--->
-
-- <test>: <link to test coverage>
+We will add tests that validate both scaling from 0 and scaling from 1 use cases.
 
 ### Graduation Criteria
 
-<!--
-**Note:** *Not required until targeted at a release.*
-
-Define graduation milestones.
-
-These may be defined in terms of API maturity, [feature gate] graduations, 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]
-- [Feature gate][feature gate] lifecycle
-- [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.
-
-[feature gate]: https://git.k8s.io/community/contributors/devel/sig-architecture/feature-gates.md
-[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/
-
-Below are some examples to consider, in addition to the aforementioned [maturity levels][maturity-levels].
-
 #### Alpha
 
-- Feature implemented behind a feature flag
+- All of the planned code changes for alpha will be done in cluster-autoscaler and not in k/k repository.
 - Initial e2e tests completed and enabled
 
+<!---
 #### Beta
 
 - Gather feedback from developers and surveys
@@ -469,9 +393,9 @@ well as the [existing list] of feature gates.
 [existing list]: https://kubernetes.io/docs/reference/command-line-tools-reference/feature-gates/
 -->
 
-- [ ] Feature gate (also fill in values in `kep.yaml`)
-  - Feature gate name:
-  - Components depending on the feature gate:
+- [x] Feature gate (also fill in values in `kep.yaml`)
+  - Feature gate name: `VolumeLimitScaling`
+  - Components depending on the feature gate: `autoscaler`, `scheduler`
 - [ ] Other
   - Describe the mechanism:
   - Will enabling / disabling the feature require downtime of the control
@@ -481,13 +405,12 @@ well as the [existing list] of feature gates.
 
 ###### Does enabling the feature change any default behavior?
 
-<!--
-Any change of default behavior may be surprising to users or break existing
-automations, so be extremely careful here.
--->
+Yes, it will cause cluster-autoscaler to consider volume limits when scaling nodes. It will also cause scheduler to not schedule pods to nodes that don't have CSI driver.
 
 ###### Can the feature be disabled once it has been enabled (i.e. can we roll back the enablement)?
 
+Yes. This will simply cause old behaviour to be restored.
+
 <!--
 Describe the consequences on existing workloads (e.g., if this is a runtime
 feature, can it break the existing applications?).
@@ -501,6 +424,8 @@ NOTE: Also set `disable-supported` to `true` or `false` in `kep.yaml`.
 
 ###### What happens if we reenable the feature if it was previously rolled back?
 
+It should work fine.
+
 ###### Are there any tests for feature enablement/disablement?
 
 <!--
@@ -636,20 +561,7 @@ This section must be completed when targeting beta to a release.
 
 ###### Does this feature depend on any specific services running in the cluster?
 
-<!--
-Think about both cluster-level services (e.g. metrics-server) as well
-as node-level agents (e.g. specific version of CRI). Focus on external or
-optional services that are needed. For example, if this feature depends on
-a cloud provider API, or upon an external software-defined storage or network
-control plane.
-
-For each of these, fill in the following—thinking about running existing user workloads
-and creating new ones, as well as about cluster-level services (e.g. DNS):
-  - [Dependency name]
-    - Usage description:
-      - Impact of its outage on the feature:
-      - Impact of its degraded performance or high-error rates on the feature:
--->
+Depends on cluster-autoscaler running in the cluster.
 
 ### Scalability
 
@@ -792,11 +704,9 @@ Why should this KEP _not_ be implemented?
 
 ## Alternatives
 
-<!--
-What other approaches did you consider, and why did you rule them out? These do
-not need to be as detailed as the proposal, but should include enough
-information to express the idea and why it was not acceptable.
--->
+
+Certain Kubernetes vendors taint the node when a new node is created and CSI driver has logic to remove the taint when CSI driver starts on the node.
+- https://github.com/kubernetes-sigs/azuredisk-csi-driver/pull/2309
 
 ## Infrastructure Needed (Optional)
 

From ec94fb9646886467a572ed2416418e56ee174973 Mon Sep 17 00:00:00 2001
From: Hemant Kumar <hekumar@redhat.com>
Date: Tue, 10 Jun 2025 17:02:16 -0400
Subject: [PATCH 03/13] Add kep approver

---
 keps/prod-readiness/sig-storage/5030.yaml | 3 +++
 1 file changed, 3 insertions(+)
 create mode 100644 keps/prod-readiness/sig-storage/5030.yaml

diff --git a/keps/prod-readiness/sig-storage/5030.yaml b/keps/prod-readiness/sig-storage/5030.yaml
new file mode 100644
index 00000000000..4ccffe99a53
--- /dev/null
+++ b/keps/prod-readiness/sig-storage/5030.yaml
@@ -0,0 +1,3 @@
+kep-number: 5030
+alpha:
+  approver: "@deads2k"

From 99f9aa742150d2b820375b9c29b7d81fcd24603d Mon Sep 17 00:00:00 2001
From: Hemant Kumar <gnufied@users.noreply.github.com>
Date: Wed, 11 Jun 2025 11:25:28 -0400
Subject: [PATCH 04/13] Update
 keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml

Co-authored-by: Drew Hagen <drewhagendev@gmail.com>
---
 keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml b/keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml
index 49fbc9d9d02..3975f9392fe 100644
--- a/keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml
+++ b/keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml
@@ -7,7 +7,7 @@ participating-sigs:
   - sig-storage
   - sig-scheduling
   - sig-autoscaling
-status: provisional
+status: implementable
 creation-date: 2025-01-09
 reviewers:
   - TBD

From f09321363703d8c4e1b34ad7e214b28246977eec Mon Sep 17 00:00:00 2001
From: Hemant Kumar <gnufied@users.noreply.github.com>
Date: Wed, 11 Jun 2025 11:25:35 -0400
Subject: [PATCH 05/13] Update
 keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml

Co-authored-by: Drew Hagen <drewhagendev@gmail.com>
---
 keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml b/keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml
index 3975f9392fe..94a9c3edd07 100644
--- a/keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml
+++ b/keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml
@@ -28,7 +28,7 @@ stage: alpha|beta|stable
 # The most recent milestone for which work toward delivery of this KEP has been
 # done. This can be the current (upcoming) milestone, if it is being actively
 # worked on.
-latest-milestone: "v1.33"
+latest-milestone: "v1.34"
 
 # The milestone at which this feature was, or is targeted to be, at each stage.
 milestone:

From f9c3c6ef08546dc4950f749a4afa354b44252409 Mon Sep 17 00:00:00 2001
From: Hemant Kumar <hekumar@redhat.com>
Date: Wed, 11 Jun 2025 11:35:25 -0400
Subject: [PATCH 06/13] Update kep.yaml with latest milestone and remove
 unneeded sections

---
 .../5030-attach-limit-autoscaler/kep.yaml     | 20 +++++--------------
 1 file changed, 5 insertions(+), 15 deletions(-)

diff --git a/keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml b/keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml
index 94a9c3edd07..332e3ea3771 100644
--- a/keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml
+++ b/keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml
@@ -16,14 +16,8 @@ reviewers:
 approvers:
   - TBD
 
-see-also:
-  - "/keps/sig-aaa/1234-we-heard-you-like-keps"
-  - "/keps/sig-bbb/2345-everyone-gets-a-kep"
-replaces:
-  - "/keps/sig-ccc/3456-replaced-kep"
-
 # The target maturity stage in the current dev cycle for this KEP.
-stage: alpha|beta|stable
+stage: alpha
 
 # The most recent milestone for which work toward delivery of this KEP has been
 # done. This can be the current (upcoming) milestone, if it is being actively
@@ -32,19 +26,15 @@ latest-milestone: "v1.34"
 
 # The milestone at which this feature was, or is targeted to be, at each stage.
 milestone:
-  alpha: "v1.33"
+  alpha: "v1.34"
   beta: "v1.35"
   stable: "v1.37"
 
 # The following PRR answers are required at alpha release
 # List the feature gate name and the components for which it must be enabled
 feature-gates:
-  - name: MyFeature
+  - name: VolumeLimitScaling
     components:
-      - kube-apiserver
-      - kube-controller-manager
+      - scheduler
+      - autoscaler
 disable-supported: true
-
-# The following PRR answers are required at beta release
-metrics:
-  - my_feature_metric

From fc012c8a9768f025a6d701b8f898b600d9785913 Mon Sep 17 00:00:00 2001
From: Hemant Kumar <hekumar@redhat.com>
Date: Wed, 11 Jun 2025 12:01:19 -0400
Subject: [PATCH 07/13] Add approvers and reviewers from sig-autoscaling too

---
 keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml b/keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml
index 332e3ea3771..c20e790e438 100644
--- a/keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml
+++ b/keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml
@@ -10,11 +10,16 @@ participating-sigs:
 status: implementable
 creation-date: 2025-01-09
 reviewers:
-  - TBD
+  - "@gjtempleton"
   - "@jsafrane"
   - "@msau42"
+  - "@elmiko"
+  - "@towca"
 approvers:
-  - TBD
+  - "@gjtempleton"
+  - "@jsafrane"
+  - "@msau42"
+  - "@towca"
 
 # The target maturity stage in the current dev cycle for this KEP.
 stage: alpha

From 33da4d98df391783b9d3c2959e728bc410640ff4 Mon Sep 17 00:00:00 2001
From: Hemant Kumar <gnufied@users.noreply.github.com>
Date: Wed, 11 Jun 2025 16:35:18 -0400
Subject: [PATCH 08/13] Update
 keps/sig-storage/5030-attach-limit-autoscaler/README.md

Co-authored-by: Kevin Hannon <kehannon@redhat.com>
---
 keps/sig-storage/5030-attach-limit-autoscaler/README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/keps/sig-storage/5030-attach-limit-autoscaler/README.md b/keps/sig-storage/5030-attach-limit-autoscaler/README.md
index c93fa94cda6..a0a80da9046 100644
--- a/keps/sig-storage/5030-attach-limit-autoscaler/README.md
+++ b/keps/sig-storage/5030-attach-limit-autoscaler/README.md
@@ -395,7 +395,7 @@ well as the [existing list] of feature gates.
 
 - [x] Feature gate (also fill in values in `kep.yaml`)
   - Feature gate name: `VolumeLimitScaling`
-  - Components depending on the feature gate: `autoscaler`, `scheduler`
+  - Components depending on the feature gate: `autoscaler`, `kube-scheduler`
 - [ ] Other
   - Describe the mechanism:
   - Will enabling / disabling the feature require downtime of the control

From 0022f89d6e871bea3397d3957146b4433f028db9 Mon Sep 17 00:00:00 2001
From: Hemant Kumar <hekumar@redhat.com>
Date: Thu, 12 Jun 2025 11:51:27 -0400
Subject: [PATCH 09/13] Change wording about not scheduling pods that require
 CSI volumes

---
 keps/sig-storage/5030-attach-limit-autoscaler/README.md | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/keps/sig-storage/5030-attach-limit-autoscaler/README.md b/keps/sig-storage/5030-attach-limit-autoscaler/README.md
index a0a80da9046..7f29cae2bc5 100644
--- a/keps/sig-storage/5030-attach-limit-autoscaler/README.md
+++ b/keps/sig-storage/5030-attach-limit-autoscaler/README.md
@@ -73,9 +73,9 @@ checklist items _must_ be updated for the enhancement to be released.
 
 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)
+- [x] (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
+- [x] (R) Design details are appropriately documented
 - [ ] (R) Test plan is in place, giving consideration to SIG Architecture and SIG Testing input (including test refactors)
   - [ ] e2e Tests for all Beta API Operations (endpoints)
   - [ ] (R) Ensure GA e2e tests meet requirements for [Conformance Tests](https://github.com/kubernetes/community/blob/master/contributors/devel/sig-architecture/conformance-tests.md) 
@@ -111,12 +111,12 @@ This leads to bunch of problems:
 
 - Since a node does not come up with a CSI driver typically, usually too many pods get scheduled on a node, which may not be supportable by the node in the first place. This leads to bunch of pods, just stuck.
 
-Once cluster-autoscaler is aware of CSI volume attach limits, we can fix kubernete's builtin scheduler to not schedule pods to nodes that don't have CSI driver installed.
+Once cluster-autoscaler is aware of CSI volume attach limits, we can fix kubernete's builtin scheduler to not schedule pods to nodes that don't have CSI driver installed and if pods require given CSI volumes.
 
 ### Goals
 
 - Modify cluster-autoscaler so as it is aware of CSI volume limits.
-- Fix scheduler, so as it doesn't schedule pods to a node that doesn't have CSI driver installed.
+- Fix scheduler, so as it doesn't schedule pods that require given CSI volume to a node that doesn't have CSI driver installed.
 
 ### Non-Goals
 

From e71d1d6b56c6bb9c22e99ecba7786dc1afc01d79 Mon Sep 17 00:00:00 2001
From: Hemant Kumar <hekumar@redhat.com>
Date: Thu, 12 Jun 2025 14:31:23 -0400
Subject: [PATCH 10/13] Add risks and mitigations and phases

---
 .../5030-attach-limit-autoscaler/README.md    | 23 +++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/keps/sig-storage/5030-attach-limit-autoscaler/README.md b/keps/sig-storage/5030-attach-limit-autoscaler/README.md
index 7f29cae2bc5..b1eceffdd3f 100644
--- a/keps/sig-storage/5030-attach-limit-autoscaler/README.md
+++ b/keps/sig-storage/5030-attach-limit-autoscaler/README.md
@@ -40,6 +40,8 @@ tags, and then generate with `hack/update-toc.sh`.
       - [e2e tests](#e2e-tests)
   - [Graduation Criteria](#graduation-criteria)
     - [Alpha](#alpha)
+      - [Phase-1](#phase-1)
+      - [Phase-2](#phase-2)
   - [Upgrade / Downgrade Strategy](#upgrade--downgrade-strategy)
   - [Version Skew Strategy](#version-skew-strategy)
 - [Production Readiness Review Questionnaire](#production-readiness-review-questionnaire)
@@ -148,6 +150,9 @@ Scheduler changes can only be merged after cluster-autoscaler changes has been G
 
 ### Risks and Mitigations
 
+As mentioned above, there is a risk associated with scheduler changes being merged before cluster-autoscaler changes can be merged, but we want to mitigate
+this by making sure cluster-autoscaler changes are merged first and has N+2 window before scheduler changes can be made GA. 
+
 <!--
 What are the risks of this proposal, and how do we mitigate? Think broadly.
 For example, consider both security and how this will impact the larger
@@ -288,8 +293,16 @@ We will add tests that validate both scaling from 0 and scaling from 1 use cases
 
 #### Alpha
 
-- All of the planned code changes for alpha will be done in cluster-autoscaler and not in k/k repository.
-- Initial e2e tests completed and enabled
+##### Phase-1
+
+- This is MVP of cnhanges in cluster-autoscaler.
+- All of the planned code changes for Phase1- alpha will be done in cluster-autoscaler and not in k/k repository.
+  We plan to impelemnt changes in cluster-autoscaler so as it can consider volume limits when scaling cluster.
+
+##### Phase-2
+- Make changes in `kube-scheduler` so as it can stop scheduling of pods that require CSI volume if underlying CSI volume is not installed on the node.
+- Initial e2e tests completed and enabled.
+
 
 <!---
 #### Beta
@@ -324,6 +337,12 @@ in back-to-back releases.
 
 ### Upgrade / Downgrade Strategy
 
+For the case of newer scheduler running with older autoscaler, we propose that `VolumeLimitScaling` feature
+should be disabled in the scheduler. 
+
+Upgrade and downgrade of `cluster-autoscaler` should be straightforward since there are no API changes 
+involved and it just means the feature will stop working once downgraded.
+
 <!--
 If applicable, how will the component be upgraded and downgraded? Make sure
 this is in the test plan.

From 3052ae968f30172bc459890acc4862ca94c9873f Mon Sep 17 00:00:00 2001
From: Hemant Kumar <hekumar@redhat.com>
Date: Mon, 16 Jun 2025 12:35:43 -0400
Subject: [PATCH 11/13] Move attach limit KEP to sig-autoscaling

---
 .../5030-attach-limit-autoscaler/README.md     | 18 ++----------------
 .../5030-attach-limit-autoscaler/kep.yaml      |  2 +-
 2 files changed, 3 insertions(+), 17 deletions(-)
 rename keps/{sig-storage => sig-autoscaling}/5030-attach-limit-autoscaler/README.md (98%)
 rename keps/{sig-storage => sig-autoscaling}/5030-attach-limit-autoscaler/kep.yaml (97%)

diff --git a/keps/sig-storage/5030-attach-limit-autoscaler/README.md b/keps/sig-autoscaling/5030-attach-limit-autoscaler/README.md
similarity index 98%
rename from keps/sig-storage/5030-attach-limit-autoscaler/README.md
rename to keps/sig-autoscaling/5030-attach-limit-autoscaler/README.md
index b1eceffdd3f..b8f8f2aafb8 100644
--- a/keps/sig-storage/5030-attach-limit-autoscaler/README.md
+++ b/keps/sig-autoscaling/5030-attach-limit-autoscaler/README.md
@@ -1,21 +1,5 @@
 # KEP-5030: Integrate Volume Attach limit into cluster autoscaler
 
-<!--
-This is the title of your KEP. Keep it short, simple, and descriptive. A good
-title can help communicate what the KEP is and should be considered as part of
-any review.
--->
-
-<!--
-A table of contents is helpful for quickly jumping to sections of a KEP and for
-highlighting any additional information provided beyond the standard KEP
-template.
-
-Ensure the TOC is wrapped with
-  <code>&lt;!-- toc --&rt;&lt;!-- /toc --&rt;</code>
-tags, and then generate with `hack/update-toc.sh`.
--->
-
 <!-- toc -->
 - [Release Signoff Checklist](#release-signoff-checklist)
 - [Summary](#summary)
@@ -132,6 +116,8 @@ As part of this proposal we are proposing changes into both cluster-autoscaler a
 2. Fix cluster-autoscaler so as it takes into account attach limits when scaling nodegroups with existing nodes.
 3. Fix kubernetes built-in scheduler so as we do not schedule pods to nodes that doesn't have CSI driver installed.
 
+Since cluster-autoscaler changes need to happen first, `kube-schduler` changes are out-of-scope for alpha implementation in v1.34.
+
 
 ### User Stories (Optional)
 
diff --git a/keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml b/keps/sig-autoscaling/5030-attach-limit-autoscaler/kep.yaml
similarity index 97%
rename from keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml
rename to keps/sig-autoscaling/5030-attach-limit-autoscaler/kep.yaml
index c20e790e438..af929b855b1 100644
--- a/keps/sig-storage/5030-attach-limit-autoscaler/kep.yaml
+++ b/keps/sig-autoscaling/5030-attach-limit-autoscaler/kep.yaml
@@ -2,7 +2,7 @@ title: Integrate CSI Volume attach limits with cluster autoscaler
 kep-number: 5030
 authors:
   - "@gnufied"
-owning-sig: sig-storage
+owning-sig: sig-autoscaling
 participating-sigs:
   - sig-storage
   - sig-scheduling

From fd4bef152126d514ac046f2b0ac83b9181ec8d63 Mon Sep 17 00:00:00 2001
From: Hemant Kumar <hekumar@redhat.com>
Date: Mon, 16 Jun 2025 13:49:16 -0400
Subject: [PATCH 12/13] Move prr to sig-autoscaling

---
 keps/prod-readiness/{sig-storage => sig-autoscaling}/5030.yaml | 0
 1 file changed, 0 insertions(+), 0 deletions(-)
 rename keps/prod-readiness/{sig-storage => sig-autoscaling}/5030.yaml (100%)

diff --git a/keps/prod-readiness/sig-storage/5030.yaml b/keps/prod-readiness/sig-autoscaling/5030.yaml
similarity index 100%
rename from keps/prod-readiness/sig-storage/5030.yaml
rename to keps/prod-readiness/sig-autoscaling/5030.yaml

From 7c7e56c9e87e9bc1cff94a800c18b0c90a6acfb9 Mon Sep 17 00:00:00 2001
From: Hemant Kumar <hekumar@redhat.com>
Date: Fri, 20 Jun 2025 12:55:55 -0400
Subject: [PATCH 13/13] Explain k8s-scheduler and autoscaler coupling

---
 .../5030-attach-limit-autoscaler/README.md       | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/keps/sig-autoscaling/5030-attach-limit-autoscaler/README.md b/keps/sig-autoscaling/5030-attach-limit-autoscaler/README.md
index b8f8f2aafb8..a82dcfc482c 100644
--- a/keps/sig-autoscaling/5030-attach-limit-autoscaler/README.md
+++ b/keps/sig-autoscaling/5030-attach-limit-autoscaler/README.md
@@ -139,6 +139,13 @@ Scheduler changes can only be merged after cluster-autoscaler changes has been G
 As mentioned above, there is a risk associated with scheduler changes being merged before cluster-autoscaler changes can be merged, but we want to mitigate
 this by making sure cluster-autoscaler changes are merged first and has N+2 window before scheduler changes can be made GA. 
 
+
+Please note the risk exists in-terms of `kube-scheduler` code that is vendored in cluster-autoscaler. The risk doesn't exist from independently running `kube-scheduler`
+and cluster-autoscaler. So we have to be careful not to vendor a version of `kube-scheduler` in cluster-autoscaler that prevents scheduling of pods (that requires CSI volumes)
+to nodes that don't have CSI driver until `cluster-autoscaler` can properly take into account CSI node limits available in upcoming node.
+
+
+
 <!--
 What are the risks of this proposal, and how do we mitigate? Think broadly.
 For example, consider both security and how this will impact the larger
@@ -323,11 +330,12 @@ in back-to-back releases.
 
 ### Upgrade / Downgrade Strategy
 
-For the case of newer scheduler running with older autoscaler, we propose that `VolumeLimitScaling` feature
-should be disabled in the scheduler. 
+In general Upgrade and Downgrade of `cluster-autoscaler` should be fine, it just means how CA scales nodes will 
+change.
 
-Upgrade and downgrade of `cluster-autoscaler` should be straightforward since there are no API changes 
-involved and it just means the feature will stop working once downgraded.
+The concern about about `kube-scheduler` and `cluster-autoscaler` coupling does not apply to running versions, it just means
+that `cluster-autoscaler` should not bundle a version of `kube-scheduler` that blocks pods(that require CSI volumes) from getting scheduled, until
+CA is properly aware of volume limits.
 
 <!--
 If applicable, how will the component be upgraded and downgraded? Make sure