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Merge pull request #30210 from voor/pod-topology-spread-constraints-fix-formatting-example

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Pod Topology Spread Constraints: Resolve formatting issue and add example for node affinity example.
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Kubernetes Prow Robot
2021-12-05 16:36:32 -08:00
committed by GitHub
parent 44ef715019 489e938f1c
commit 8abfbc924e
1 changed files with 4 additions and 2 deletions
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content/en/docs/concepts/workloads/pods/pod-topology-spread-constraints.md
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@@ -85,7 +85,7 @@ You can define one or multiple `topologySpreadConstraint` to instruct the kube-s
It must be greater than zero. Its semantics differs according to the value of `whenUnsatisfiable`: It must be greater than zero. Its semantics differs according to the value of `whenUnsatisfiable`:
- when `whenUnsatisfiable` equals to "DoNotSchedule", `maxSkew` is the maximum - when `whenUnsatisfiable` equals to "DoNotSchedule", `maxSkew` is the maximum
permitted difference between the number of matching pods in the target permitted difference between the number of matching pods in the target
topology and the global minimum topology and the global minimum
(the minimum number of pods that match the label selector in a topology domain. For example, if you have 3 zones with 0, 2 and 3 matching pods respectively, The global minimum is 0). (the minimum number of pods that match the label selector in a topology domain. For example, if you have 3 zones with 0, 2 and 3 matching pods respectively, The global minimum is 0).
- when `whenUnsatisfiable` equals to "ScheduleAnyway", scheduler gives higher - when `whenUnsatisfiable` equals to "ScheduleAnyway", scheduler gives higher
precedence to topologies that would help reduce the skew. precedence to topologies that would help reduce the skew.
@@ -234,6 +234,8 @@ To overcome this situation, you can either increase the `maxSkew` or modify one
The scheduler will skip the non-matching nodes from the skew calculations if the incoming Pod has `spec.nodeSelector` or `spec.affinity.nodeAffinity` defined. The scheduler will skip the non-matching nodes from the skew calculations if the incoming Pod has `spec.nodeSelector` or `spec.affinity.nodeAffinity` defined.
### Example: TopologySpreadConstraints with NodeAffinity
Suppose you have a 5-node cluster ranging from zoneA to zoneC: Suppose you have a 5-node cluster ranging from zoneA to zoneC:
{{<mermaid>}} {{<mermaid>}}
@@ -392,7 +394,7 @@ for more details.
## Known Limitations ## Known Limitations
- There's no guarantee that the constraints remain satisfied when Pods are removed. For example, scaling down a Deployment may result in imbalanced Pods distribution. - There's no guarantee that the constraints remain satisfied when Pods are removed. For example, scaling down a Deployment may result in imbalanced Pods distribution.
You can use [Descheduler](https://github.com/kubernetes-sigs/descheduler) to rebalance the Pods distribution. You can use [Descheduler](https://github.com/kubernetes-sigs/descheduler) to rebalance the Pods distribution.
- Pods matched on tainted nodes are respected. See [Issue 80921](https://github.com/kubernetes/kubernetes/issues/80921) - Pods matched on tainted nodes are respected. See [Issue 80921](https://github.com/kubernetes/kubernetes/issues/80921)