OSDOCS#12034: HCP Kubevirt topology spread constraint by xenolinux · Pull Request #93263 · openshift/openshift-docs

xenolinux · 2025-05-13T10:52:07Z

Version(s): 4.18+

Issue: Issue: https://issues.redhat.com/browse/OSDOCS-12034

Link to docs preview: https://93263--ocpdocs-pr.netlify.app/openshift-enterprise/latest/hosted_control_planes/hcp-manage/hcp-manage-virt.html#hcp-topology-spread-constraint_hcp-manage-virt

QE review:

QE has approved this change.

SME review:

SME has approved this change.

Additional information:

This content is QE/SME approved and peer-reviewed. It was reverted as per QE's suggestion. Adding the same content back to docs. Newly added content is reviewed by SMEs.

ocpdocs-previewbot · 2025-05-13T11:02:04Z

🤖 Thu May 15 16:08:20 - Prow CI generated the docs preview:

https://93263--ocpdocs-pr.netlify.app/openshift-enterprise/latest/hosted_control_planes/hcp-manage/hcp-manage-virt.html

tiraboschi · 2025-05-13T13:06:04Z

modules/hcp-topology-spread-constraint.adoc

+  - SoftTopologyAndDuplicates   // <2>
+  - EvictPodsWithPVC           // <3>
+  - EvictPodsWithLocalStorage // <4>
+  - LongLifecycle            // <5>


I'd suggest:

apiVersion: operator.openshift.io/v1 kind: KubeDescheduler metadata: name: cluster namespace: openshift-kube-descheduler-operator spec: managementState: Managed deschedulingIntervalSeconds: 30 mode: "Automatic" profiles: - DevKubeVirtRelieveAndMigrate - SoftTopologyAndDuplicates profileCustomizations: devEnableSoftTainter: true devDeviationThresholds: AsymmetricLow devActualUtilizationProfile: PrometheusCPUCombined

DevKubeVirtRelieveAndMigrate is an enhanced variant of LongLifecycle for the Kubevirt use case.
With that EvictPodsWithPVC and EvictPodsWithLocalStorage are implicitly enabled.

tiraboschi · 2025-05-13T13:06:49Z

modules/hcp-topology-spread-constraint.adoc

+<3> By default, the {descheduler-operator} prevents the pod eviction with persistent volume claims (PVCs). Use this profile to allow eviction of pods with PVCs.
+<4> By default, pods with local storage are not eligible for eviction. Use this profile to allow eviction of your VMs that use the local storage.


with DevKubeVirtRelieveAndMigrate we can avoid those two.

tiraboschi · 2025-05-13T13:07:25Z

modules/hcp-topology-spread-constraint.adoc

+<2> This profile evicts pods that follow the soft topology constraint: `whenUnsatisfiable: ScheduleAnyway`.
+<3> By default, the {descheduler-operator} prevents the pod eviction with persistent volume claims (PVCs). Use this profile to allow eviction of pods with PVCs.
+<4> By default, pods with local storage are not eligible for eviction. Use this profile to allow eviction of your VMs that use the local storage.
+<5> This profile balances resource usage between nodes and enables the strategies, such as `RemovePodsHavingTooManyRestarts` and `LowNodeUtilization`.


the same consideration is valid for DevKubeVirtRelieveAndMigrate

tiraboschi · 2025-05-13T13:07:43Z

modules/hcp-topology-spread-constraint.adoc

+<3> By default, the {descheduler-operator} prevents the pod eviction with persistent volume claims (PVCs). Use this profile to allow eviction of pods with PVCs.
+<4> By default, pods with local storage are not eligible for eviction. Use this profile to allow eviction of your VMs that use the local storage.
+<5> This profile balances resource usage between nodes and enables the strategies, such as `RemovePodsHavingTooManyRestarts` and `LowNodeUtilization`.
+<6> You must use this setting when performing a live migration so that the descheduler runs in the background during the migration process.


This is not needed with DevKubeVirtRelieveAndMigrate

LiangquanLi930 · 2025-05-15T08:33:32Z

/lgtm

tmalove · 2025-05-15T13:04:35Z

/remove-label peer-review-needed
/label peer-review-in-progress

tmalove · 2025-05-15T13:19:15Z

modules/hcp-topology-spread-constraint.adoc

+    devActualUtilizationProfile: PrometheusCPUCombined
+# ...
+----
+<1> Sets the number of seconds between the descheduler running cycles.


Did you mean to also comment out the callout lines? The preview looks good though.

Fixed

Added # for call outs

tmalove · 2025-05-15T13:26:56Z

modules/hcp-topology-spread-constraint.adoc

+
+By default, KubeVirt virtual machines (VMs) created by a node pool are scheduled on any available nodes that have the capacity to run the VMs. By default, the `topologySpreadConstraint` constraint is set to schedule VMs on multiple nodes.
+
+In some scenarios, node pool VMs might run on the same node, which can cause availability issues. To avoid distribution of VMs on a single node, use the descheduler to continuously honour the `topologySpreadConstraint` constraint to spread VMs on multiple nodes.


Suggested change

In some scenarios, node pool VMs might run on the same node, which can cause availability issues. To avoid distribution of VMs on a single node, use the descheduler to continuously honour the `topologySpreadConstraint` constraint to spread VMs on multiple nodes.

In some scenarios, node pool VMs might run on the same node, which can cause availability issues. To avoid distribution of VMs on a single node, use the descheduler to continuously honor the `topologySpreadConstraint` constraint to spread VMs on multiple nodes.

tmalove · 2025-05-15T13:28:31Z

/remove-label peer-review-in-progress
/label peer-review-done
One small nit, otherwise lgtm!

openshift-ci · 2025-05-15T15:47:11Z

New changes are detected. LGTM label has been removed.

openshift-ci · 2025-05-15T16:09:24Z

@xenolinux: all tests passed!

Full PR test history. Your PR dashboard.

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xenolinux · 2025-05-15T16:21:28Z

/cherrypick enterprise-4.19

xenolinux · 2025-05-15T16:21:33Z

/cherrypick enterprise-4.18

openshift-cherrypick-robot · 2025-05-15T16:22:17Z

@xenolinux: new pull request created: #93449

Details

In response to this:

/cherrypick enterprise-4.19

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openshift-cherrypick-robot · 2025-05-15T16:22:20Z

@xenolinux: new pull request created: #93450

Details

In response to this:

/cherrypick enterprise-4.18

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openshift-ci bot added the size/M Denotes a PR that changes 30-99 lines, ignoring generated files. label May 13, 2025

xenolinux added this to the Continuous Release milestone May 13, 2025

xenolinux added branch/enterprise-4.18 branch/enterprise-4.19 labels May 13, 2025

xenolinux force-pushed the add-topology-hcp branch from 23c34a2 to 8825f04 Compare May 13, 2025 11:12

tiraboschi reviewed May 13, 2025

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xenolinux force-pushed the add-topology-hcp branch 2 times, most recently from 7a76bf4 to ebfb886 Compare May 14, 2025 08:05

tiraboschi approved these changes May 14, 2025

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openshift-ci bot assigned LiangquanLi930 May 15, 2025

openshift-ci bot added the lgtm Indicates that a PR is ready to be merged. label May 15, 2025

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xenolinux force-pushed the add-topology-hcp branch from ebfb886 to 4fca8a7 Compare May 15, 2025 15:46

openshift-ci bot removed the lgtm Indicates that a PR is ready to be merged. label May 15, 2025

OSDOCS#12034: HCP Kubevirt topology spread constraint

a7ad529

xenolinux force-pushed the add-topology-hcp branch from 4fca8a7 to a7ad529 Compare May 15, 2025 15:51

xenolinux merged commit 0c980f4 into openshift:main May 15, 2025
2 checks passed

xenolinux deleted the add-topology-hcp branch May 15, 2025 16:21

openshift-cherrypick-robot mentioned this pull request May 15, 2025

[enterprise-4.19] OSDOCS#12034: HCP Kubevirt topology spread constraint #93449

Merged

openshift-cherrypick-robot mentioned this pull request May 15, 2025

[enterprise-4.18] OSDOCS#12034: HCP Kubevirt topology spread constraint #93450

Merged

		<3> By default, the {descheduler-operator} prevents the pod eviction with persistent volume claims (PVCs). Use this profile to allow eviction of pods with PVCs.
		<4> By default, pods with local storage are not eligible for eviction. Use this profile to allow eviction of your VMs that use the local storage.


		By default, KubeVirt virtual machines (VMs) created by a node pool are scheduled on any available nodes that have the capacity to run the VMs. By default, the `topologySpreadConstraint` constraint is set to schedule VMs on multiple nodes.

		In some scenarios, node pool VMs might run on the same node, which can cause availability issues. To avoid distribution of VMs on a single node, use the descheduler to continuously honour the `topologySpreadConstraint` constraint to spread VMs on multiple nodes.

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