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Promote PodTopologySpread to stable in 1.19

pull/21115/head
Wei Huang 2020-07-15 10:42:44 -07:00 committed by Wei Huang
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22
content/en/docs/concepts/workloads/pods/pod-topology-spread-constraints.md
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@ -6,8 +6,6 @@ weight: 50
<!-- overview -->
{{< feature-state for_k8s_version="v1.18" state="beta" >}}
You can use _topology spread constraints_ to control how {{< glossary_tooltip text="Pods" term_id="Pod" >}} are spread across your cluster among failure-domains such as regions, zones, nodes, and other user-defined topology domains. This can help to achieve high availability as well as efficient resource utilization.
@ -16,13 +14,6 @@ You can use _topology spread constraints_ to control how {{< glossary_tooltip te
## Prerequisites
### Enable Feature Gate
The `EvenPodsSpread` [feature gate](/docs/reference/command-line-tools-reference/feature-gates/)
must be enabled for the
{{< glossary_tooltip text="API Server" term_id="kube-apiserver" >}} **and**
{{< glossary_tooltip text="scheduler" term_id="kube-scheduler" >}}.
### Node Labels
Topology spread constraints rely on node labels to identify the topology domain(s) that each Node is in. For example, a Node might have labels: `node=node1,zone=us-east-1a,region=us-east-1`
@ -53,7 +44,7 @@ Instead of manually applying labels, you can also reuse the [well-known labels](
### API
The field `pod.spec.topologySpreadConstraints` is introduced in 1.16 as below:
The API field `pod.spec.topologySpreadConstraints` is defined as below:
```
apiVersion: v1
@ -265,13 +256,14 @@ scheduled - more packed or more scattered.
- For `PodAntiAffinity`, only one Pod can be scheduled into a
single topology domain.
The "EvenPodsSpread" feature provides flexible options to distribute Pods evenly across different
topology domains - to achieve high availability or cost-saving. This can also help on rolling update
workloads and scaling out replicas smoothly. See [Motivation](https://github.com/kubernetes/enhancements/tree/master/keps/sig-scheduling/895-pod-topology-spread#motivation) for more details.
For finer control, you can specify topology spread constraints to distribute
Pods across different topology domains - to achieve either high availability or
cost-saving. This can also help on rolling update workloads and scaling out
replicas smoothly. See
[Motivation](https://github.com/kubernetes/enhancements/tree/master/keps/sig-scheduling/895-pod-topology-spread#motivation)
for more details.
## Known Limitations
- Scaling down a Deployment may result in imbalanced Pods distribution.
- Pods matched on tainted nodes are respected. See [Issue 80921](https://github.com/kubernetes/kubernetes/issues/80921)

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content/en/docs/reference/command-line-tools-reference/feature-gates.md
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@ -101,8 +101,6 @@ different Kubernetes components.
| `ExpandPersistentVolumes` | `false` | Alpha | 1.8 | 1.10 |
| `ExpandPersistentVolumes` | `true` | Beta | 1.11 | |
| `ExperimentalHostUserNamespaceDefaulting` | `false` | Beta | 1.5 | |
| `EvenPodsSpread` | `false` | Alpha | 1.16 | 1.17 |
| `EvenPodsSpread` | `true` | Beta | 1.18 | |
| `GenericEphemeralVolume` | `false` | Alpha | 1.19 | |
| `HPAScaleToZero` | `false` | Alpha | 1.16 | |
| `HugePageStorageMediumSize` | `false` | Alpha | 1.18 | 1.18 |
@ -225,6 +223,9 @@ different Kubernetes components.
| `EnableEquivalenceClassCache` | - | Deprecated | 1.15 | - |
| `ExperimentalCriticalPodAnnotation` | `false` | Alpha | 1.5 | 1.12 |
| `ExperimentalCriticalPodAnnotation` | `false` | Deprecated | 1.13 | - |
| `EvenPodsSpread` | `false` | Alpha | 1.16 | 1.17 |
| `EvenPodsSpread` | `true` | Beta | 1.18 | 1.18 |
| `EvenPodsSpread` | `true` | GA | 1.19 | - |
| `GCERegionalPersistentDisk` | `true` | Beta | 1.10 | 1.12 |
| `GCERegionalPersistentDisk` | `true` | GA | 1.13 | - |
| `HugePages` | `false` | Alpha | 1.8 | 1.9 |