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scheduler: more informative generic ephemeral volume events #104605

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merged 1 commit into from Sep 4, 2021
Merged

scheduler: more informative generic ephemeral volume events #104605

merged 1 commit into from Sep 4, 2021

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pohly
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@pohly pohly commented Aug 26, 2021 •
edited

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

Typically, pods using generic ephemeral inline volumes trigger two events:

  Type     Reason            Age   From               Message
  ----     ------            ----  ----               -------
  Warning  FailedScheduling  3s    default-scheduler  0/1 nodes are available: 1 persistentvolumeclaim "my-csi-app-inline-volume-my-csi-volume" not found.
  Warning  FailedScheduling  2s    default-scheduler  0/1 nodes are available: 1 pod has unbound immediate PersistentVolumeClaims.

The first now is more informative:

   Type     Reason            Age   From               Message
   ----     ------            ----  ----               -------
   Warning  FailedScheduling  4s    default-scheduler  0/1 nodes are available: 1 waiting for ephemeral volume controller to create the persistentvolumeclaim "my-csi-app-inline-volume-my-csi-volume".
   Warning  FailedScheduling  2s    default-scheduler  0/1 nodes are available: 1 pod has unbound immediate PersistentVolumeClaims.

Which issue(s) this PR fixes:

Fixes #104525

Special notes for your reviewer:

Originally, this PR also contained a second commit which delayed the first event and, as a result, typically never showed it because the condition for it is short-lived. This was taken out based on review feedback but could be brought back if desired: https://github.com/pohly/kubernetes/commits/ephemeral-volume-events-delay

Does this PR introduce a user-facing change?

generic ephemeral volumes: better pod events ("waiting for ephemeral volume controller to create the persistentvolumeclaim"" instead of "persistentvolumeclaim not found")

@k8s-ci-robot k8s-ci-robot added kind/cleanup Categorizes issue or PR as related to cleaning up code, process, or technical debt. do-not-merge/release-note-label-needed Indicates that a PR should not merge because it's missing one of the release note labels. size/M Denotes a PR that changes 30-99 lines, ignoring generated files. cncf-cla: yes Indicates the PR's author has signed the CNCF CLA. do-not-merge/needs-sig Indicates an issue or PR lacks a `sig/foo` label and requires one. labels Aug 26, 2021
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@pohly: This issue is currently awaiting triage.

If a SIG or subproject determines this is a relevant issue, they will accept it by applying the triage/accepted label and provide further guidance.

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@k8s-ci-robot k8s-ci-robot added needs-triage Indicates an issue or PR lacks a `triage/foo` label and requires one. needs-priority Indicates a PR lacks a `priority/foo` label and requires one. labels Aug 26, 2021
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pohly commented Aug 26, 2021

/sig storage
/sig scheduling

@k8s-ci-robot k8s-ci-robot added sig/storage Categorizes an issue or PR as relevant to SIG Storage. sig/scheduling Categorizes an issue or PR as relevant to SIG Scheduling. and removed do-not-merge/needs-sig Indicates an issue or PR lacks a `sig/foo` label and requires one. labels Aug 26, 2021
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ahg-g commented Aug 27, 2021

Thanks @pohly, I don't think the second commit is necessary, I think it is better for debugging to have the events consistent with pod conditions.

@k8s-ci-robot k8s-ci-robot added size/XS Denotes a PR that changes 0-9 lines, ignoring generated files. release-note Denotes a PR that will be considered when it comes time to generate release notes. and removed size/M Denotes a PR that changes 30-99 lines, ignoring generated files. do-not-merge/release-note-label-needed Indicates that a PR should not merge because it's missing one of the release note labels. labels Aug 30, 2021
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pohly commented Aug 30, 2021

I don't think the second commit is necessary, I think it is better for debugging to have the events consistent with pod conditions.

Okay. I've taken out that second part and updated the PR description accordingly.

/assign @msau42

@pohly
scheduler: better reason for delay with generic ephemeral volumes
89cb4d0 
These events are currently emitted for a pod using a generic ephemeral volume:

  Type     Reason            Age   From               Message
  ----     ------            ----  ----               -------
  Warning  FailedScheduling  3s    default-scheduler  0/1 nodes are available: 1 persistentvolumeclaim "my-csi-app-inline-volume-my-csi-volume" not found.
  Warning  FailedScheduling  2s    default-scheduler  0/1 nodes are available: 1 pod has unbound immediate PersistentVolumeClaims.

The one about "persistentvolumeclaim not found" is potentially confusing. It
occurs because the scheduler typically checks the pod before the ephemeral
volume controller had a chance to create the PVC.

This is a bit easier to understand:

  Type     Reason            Age   From               Message
  ----     ------            ----  ----               -------
  Warning  FailedScheduling  4s    default-scheduler  0/1 nodes are available: 1 waiting for ephemeral volume controller to create the persistentvolumeclaim "my-csi-app-inline-volume-my-csi-volume".
  Warning  FailedScheduling  2s    default-scheduler  0/1 nodes are available: 1 pod has unbound immediate PersistentVolumeClaims.
ahg-g
ahg-g reviewed Aug 30, 2021
View reviewed changes
pkg/scheduler/framework/plugins/volumebinding/volume_binding.go
// but we can do better for generic ephemeral inline volumes where that situation
// is normal directly after creating a pod.
if ephemeral && apierrors.IsNotFound(err) {
err = fmt.Errorf("waiting for ephemeral volume controller to create the persistentvolumeclaim %q", pvcName)
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is it always the case that this type of PVC is created by the ephemeral volume controller?

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In practice, yes. It would be possible to set up a cluster where that controller is disabled and some other entity creates the PVCs, but that seems very unlikely.

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ahg-g commented Aug 30, 2021

/approve
leaving lgtm to @msau42

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[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ahg-g, pohly

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@k8s-ci-robot k8s-ci-robot added the approved Indicates a PR has been approved by an approver from all required OWNERS files. label Aug 30, 2021
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msau42 commented Sep 3, 2021

/lgtm

@k8s-ci-robot k8s-ci-robot added the lgtm "Looks good to me", indicates that a PR is ready to be merged. label Sep 3, 2021
@k8s-ci-robot k8s-ci-robot merged commit b12379e into kubernetes:master Sep 4, 2021
@k8s-ci-robot k8s-ci-robot added this to the v1.23 milestone Sep 4, 2021
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@ahg-g ahg-g ahg-g left review comments

@chendave chendave Awaiting requested review from chendave

@verult verult Awaiting requested review from verult

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approved Indicates a PR has been approved by an approver from all required OWNERS files. cncf-cla: yes Indicates the PR's author has signed the CNCF CLA. kind/cleanup Categorizes issue or PR as related to cleaning up code, process, or technical debt. lgtm "Looks good to me", indicates that a PR is ready to be merged. needs-priority Indicates a PR lacks a `priority/foo` label and requires one. needs-triage Indicates an issue or PR lacks a `triage/foo` label and requires one. release-note Denotes a PR that will be considered when it comes time to generate release notes. sig/scheduling Categorizes an issue or PR as relevant to SIG Scheduling. sig/storage Categorizes an issue or PR as relevant to SIG Storage. size/XS Denotes a PR that changes 0-9 lines, ignoring generated files.
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generic ephemeral volumes: avoid emitting unnecessary events
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