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reopen KEP 1860
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RyanAoh authored and Aohan committed Aug 4, 2023
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6 changes: 6 additions & 0 deletions keps/prod-readiness/sig-network/1860.yaml
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# The KEP must have an approver from the
# "prod-readiness-approvers" group
# of http://git.k8s.io/enhancements/OWNERS_ALIASES
kep-number: 1860
alpha:
approver: "@wojtek-t"
304 changes: 298 additions & 6 deletions keps/sig-network/1860-kube-proxy-IP-node-binding/README.md
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Expand Up @@ -23,6 +23,13 @@
- [Beta/GA](#betaga)
- [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)
<!-- /toc -->

## Release Signoff Checklist
Expand All @@ -32,13 +39,17 @@ Items marked with (R) are required *prior to targeting to a milestone / release*
- [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
- [ ] (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
- [ ] Production readiness review approved
- [ ] (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
- [ ] Supporting documentatione.g., additional design documents, links to mailing list discussions/SIG meetings, relevant PRs/issues, release notes


## Summary
Expand Down Expand Up @@ -122,7 +133,6 @@ API changes to Service:
Unit tests:
- unit tests for the ipvs and iptables rules
- unit tests for the validation
- unit tests for a new util in pkg/proxy

E2E tests:
- The default behavior for `ipMode` does not break any existing e2e tests
Expand All @@ -140,7 +150,8 @@ Adds new field `ipMode` to Service, which is used when `LoadBalancerIPMode` feat

### Upgrade / Downgrade Strategy

On upgrade, while the feature gate is disabled, nothing will change. Once the feature gate is enabled, all the previous LoadBalancer service will get an `ipMode` of `VIP`.
On upgrade, while the feature gate is disabled, nothing will change. Once the feature gate is enabled,
all the previous LoadBalancer service will get an `ipMode` of `VIP` by the defaulting function when we get them from kube-apiserver.
If `kube-proxy` was not yet upgraded: the field will simply be ignored.
If `kube-proxy` was upgraded, and the feature gate enabled, it will stil behave as before if the `ipMode` is `VIP`, and will behave accordingly if the `ipMode` is `Proxy`.

Expand All @@ -149,3 +160,284 @@ On downgrade, the feature gate will simply be disabled, and as long as `kube-pro
### Version Skew Strategy

Version skew from the control plane to `kube-proxy` should be trivial since `kube-proxy` will simply ignore the `ipMode` field.

## Production Readiness Review Questionnaire

### Feature Enablement and Rollback

###### How can this feature be enabled / disabled in a live cluster?

- [x] Feature gate (also fill in values in `kep.yaml`)
- Feature gate name: LoadBalancerIPMode
- Components depending on the feature gate: kube-proxy, kube-apiserver, cloud-controller-manager

###### Does enabling the feature change any default behavior?

No.

###### Can the feature be disabled once it has been enabled (i.e. can we roll back the enablement)?

Yes, by disabling the feature gate. Disabling it in kube-proxy is necessary and sufficient to have a user-visible effect.

###### What happens if we reenable the feature if it was previously rolled back?

It works. The forwarding rules for services which have the value of `ipMode` had been set to "Proxy" will be removed by kube-proxy.

###### Are there any tests for feature enablement/disablement?

Yes. The test `TestUpdateServiceLoadBalancerStatus` in pkg/registry/core/service/storage/storage_test.go did this.

### 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?
13 changes: 7 additions & 6 deletions keps/sig-network/1860-kube-proxy-IP-node-binding/kep.yaml
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Expand Up @@ -14,18 +14,19 @@ approvers:
- "@thockin"
- "@andrewsykim"

# latest-milestone: "v1.21"
stage: "alpha"

latest-milestone: "v1.29"

milestone:
alpha: "v1.21"
beta: "v1.22"
alpha: "v1.29"
beta: "v1.30"
stable: "v1.31"

feature-gates:
- name: LoadBalancerIPMode
components:
- kube-apiserver
- kube-proxy
- cloud-controller-manager
disable-supported: true

latest-milestone: "0.0"
stage: "alpha"

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