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Merge pull request #3375 from soltysh/cronjob_timezone_beta
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KEP-3140: TimeZone support in CronJob
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k8s-ci-robot authored Jun 13, 2022
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2 changes: 2 additions & 0 deletions keps/prod-readiness/sig-apps/3140.yaml
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kep-number: 3140
alpha:
approver: deads2k
beta:
approver: deads2k
254 changes: 90 additions & 164 deletions keps/sig-apps/3140-TimeZone-support-in-CronJob/README.md
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Expand Up @@ -13,6 +13,10 @@
- [CronJob API](#cronjob-api)
- [CronJob controller](#cronjob-controller)
- [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)
- [Beta](#beta)
Expand All @@ -39,17 +43,17 @@ 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
- [ ] (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 for 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)
- [x] (R) Test plan is in place, giving consideration to SIG Architecture and SIG Testing input (including test refactors)
- [x] e2e Tests for all Beta API Operations (endpoints)
- [x] (R) Ensure GA e2e tests for meet requirements for [Conformance Tests](https://github.com/kubernetes/community/blob/master/contributors/devel/sig-architecture/conformance-tests.md)
- [x] (R) Minimum Two Week Window for GA e2e tests to prove flake free
- [x] (R) Graduation criteria is in place
- [x] (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)
- [x] (R) Production readiness review completed
- [x] (R) Production readiness review approved
- [x] "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
- [x] User-facing documentation has been created in [kubernetes/website], for publication to [kubernetes.io]
- [x] 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.
Expand Down Expand Up @@ -159,14 +163,29 @@ In all other cases the controller will maintain the current behavior.

### Test Plan

Unit and integration tests covering the time zone mechanics of CronJob, including:
[x] 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.

- defaulting
- validation
- creating CronJob
- updating CronJob
##### Prerequisite testing updates

Additionally, all of tests will be performed with feature gate enabled and disabled.
1. Add tests ensuring that case insensitive location loading is properly handled.
See [beta requirements](#beta) for more details.
2. Add at least integration and optionally e2e covering TimeZone usage.

##### Unit tests

- `k8s.io/kubernetes/pkg/apis/batch/validation`: `2022-06-09` - `94.4%`
- `k8s.io/kubernetes/pkg/controller/cronjob`: `2022-06-09` - `50.8%`
- `k8s.io/kubernetes/pkg/registry/batch/cronjob`: `2022-06-09` - `61.8%`

##### Integration tests

None.

##### e2e tests

None.

### Graduation Criteria

Expand All @@ -182,8 +201,6 @@ Additionally, all of tests will be performed with feature gate enabled and disab
- Test skipped on MacOS (https://github.com/kubernetes/kubernetes/pull/109218)
- Golang issue (https://github.com/golang/go/issues/21512)

More TBD

#### GA

TBD
Expand Down Expand Up @@ -251,7 +268,6 @@ This feature has no node runtime implications.

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


- [x] Feature gate (also fill in values in `kep.yaml`)
- Feature gate name: CronJobTimeZone
- Components depending on the feature gate: kube-apiserver, kube-controller-manager
Expand Down Expand Up @@ -279,151 +295,80 @@ Yes, both units and integration tests for enablement, disablement and transition

### 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.
-->

An upgrade flow can be vulnerable to the enable, disable, enable if you have
a lease that is acquired by a new kube-controller-manager, then an old
kube-controller-manager, then a new kube-controller-manager.

###### 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?
-->
Increased `cronjob_job_creation_skew` which tracks how much a job creation
is delayed compared to requested time slot.

###### 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.
-->
Upgrade->downgrade->upgrade path was manually tested. No issues were found during tests.

###### 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.
-->
No.

### Monitoring Requirements

<!--
This section must be completed when targeting beta to a release.
-->

###### 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.
-->
There's no explicit metric for TimeZone but operator should monitor `cronjob_job_creation_skew`,
ensuring the job creation skew is not increasing.

###### 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:
- [x] Events
- Event Reason: `UnknownTimeZone` when specified TimeZone is not correct

###### 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.
-->
99th percentile over day for cron_job_creation_skew is <= 15s

###### 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.
-->

- [x] Metrics
- Metric name: `cronjob_controller_rate_limiter_use`
- Components exposing the metric: `kube-controller-manager`
- [ ] Other (treat as last resort)
- Details:
- Metric name: `cron_job_creation_skew`
- Components exposing the metric: `kube-controller-manager`


###### 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.).
-->
No.

### 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:
-->
CronJob's TimeZone support relies on external TimeZone package, if one is missing
golang's internal package will be used, instead.

- kube-controller-manager and kube-apiserver
- Usage description:
Both kube-controller-manager and kube-apiserver need to have `CronJobTimeZone`
feature gate turned for this feature to fully work.
- Impact of its outage on the feature:
CronJob's TimeZone functionality will not work.
- Impact of its degraded performance or high-error rates on the feature:
Delays in creating new Jobs.

- TimeZone package
- Usage description: CronJob's TimeZone support relies on external TimeZone package,
if one is missing golang's internal package will be used, instead.
- Impact of its outage on the feature:
TimeZone functionality will not work.
- Impact of its degraded performance or high-error rates on the feature:
Delays in creating new Jobs.

### 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?

No new API calls are expected.
Expand Down Expand Up @@ -455,67 +400,48 @@ We're not using it, yet.

### Troubleshooting

<!--
This section must be completed when targeting beta to a release.
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.
-->
- Incorrect TimeZone
- Detection: `UnknownTimeZone` events being reported for a CronJob.
- Mitigations: Fix the TimeZone or suspend a CronJob.
- Diagnostics: Logs containing `TimeZone` phrase.
- Testing: A set of unit tests is ensuring that invalid TimeZone is properly
handled both in the apiserver and in the controller itself, reporting to
user the problem.
- Job creation problems
- Detection: `cron_job_creation_skew` metric is exceeding expected 15s per day.
- Mitigations: Disable `CronJobTimeZone` feature gate.
- Diagnostics: Check logs from CronJob controller.
- Testing: A set of unit tests is ensuring that invalid TimeZone is properly
handled both in the apiserver and in the controller itself, reporting to
user the problem.

###### What steps should be taken if SLOs are not being met to determine the problem?

If possible increase the log level for kube-controller-manager and check cronjob's
controller logs looking for warnings and errors which might point where the problem
lies.

## 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
-->
- *2022-01-14* - Initial KEP draft
- *2022-06-09* - Updated KEP for beta promotion.

## Drawbacks

<!--
Why should this KEP _not_ be implemented?
-->
Using TimeZone might be simpler for users working with a cluster in different
TimeZones, but adds additional complexity to the code and to the operator
who will need to re-calculate when an actual CronJob will be creating a Job
when `.spec.timeZone` is set.

## Alternatives

Another approach was to specify time zone as an offset to UTC, but using the
name instead seems more user friendly.

<!--
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.
-->
None.
6 changes: 3 additions & 3 deletions keps/sig-apps/3140-TimeZone-support-in-CronJob/kep.yaml
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Expand Up @@ -18,12 +18,12 @@ see-also:
replaces:

# The target maturity stage in the current dev cycle for this KEP.
stage: alpha
stage: beta

# 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: "v1.24"
latest-milestone: "v1.25"

# The milestone at which this feature was, or is targeted to be, at each stage.
milestone:
Expand All @@ -42,4 +42,4 @@ disable-supported: true

# The following PRR answers are required at beta release
metrics:
# - my_feature_metric
- cron_job_creation_skew

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