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Update graceful node shutdown beta docs

This commit is contained in:
David Porter 2021-03-08 18:15:10 -08:00
parent a8ebc3c3f6
commit b222a13525
2 changed files with 27 additions and 9 deletions
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33
content/en/docs/concepts/architecture/nodes.md
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@ -334,26 +334,43 @@ the kubelet can use topology hints when making resource assignment decisions.
See [Control Topology Management Policies on a Node](/docs/tasks/administer-cluster/topology-manager/)
for more information.
## Graceful Node Shutdown {#graceful-node-shutdown}
## Graceful node shutdown {#graceful-node-shutdown}
{{< feature-state state="alpha" for_k8s_version="v1.20" >}}
{{< feature-state state="beta" for_k8s_version="v1.21" >}}
The kubelet attempts to detect node system shutdown and terminates pods running on the node.
If you have enabled the `GracefulNodeShutdown` [feature gate](/docs/reference/command-line-tools-reference/feature-gates/), then the kubelet attempts to detect the node system shutdown and terminates pods running on the node.
Kubelet ensures that pods follow the normal [pod termination process](/docs/concepts/workloads/pods/pod-lifecycle/#pod-termination) during the node shutdown.
When the `GracefulNodeShutdown` feature gate is enabled, kubelet uses [systemd inhibitor locks](https://www.freedesktop.org/wiki/Software/systemd/inhibit/) to delay the node shutdown with a given duration. During a shutdown, kubelet terminates pods in two phases:
The Graceful node shutdown feature depends on systemd since it takes advantage of
[systemd inhibitor locks](https://www.freedesktop.org/wiki/Software/systemd/inhibit/) to
delay the node shutdown with a given duration.
Graceful node shutdown is controlled with the `GracefulNodeShutdown`
[feature gate](/docs/reference/command-line-tools-reference/feature-gates/) which is
enabled by default in 1.21.
Note that by default, both configuration options described below,
`ShutdownGracePeriod` and `ShutdownGracePeriodCriticalPods` are set to zero,
thus not activating Graceful node shutdown functionality.
To activate the feature, the two kubelet config settings should be configured appropriately and set to non-zero values.
During a graceful shutdown, kubelet terminates pods in two phases:
1. Terminate regular pods running on the node.
2. Terminate [critical pods](/docs/tasks/administer-cluster/guaranteed-scheduling-critical-addon-pods/#marking-pod-as-critical) running on the node.
Graceful Node Shutdown feature is configured with two [`KubeletConfiguration`](/docs/tasks/administer-cluster/kubelet-config-file/) options:
Graceful node shutdown feature is configured with two [`KubeletConfiguration`](/docs/tasks/administer-cluster/kubelet-config-file/) options:
* `ShutdownGracePeriod`:
* Specifies the total duration that the node should delay the shutdown by. This is the total grace period for pod termination for both regular and [critical pods](/docs/tasks/administer-cluster/guaranteed-scheduling-critical-addon-pods/#marking-pod-as-critical).
* `ShutdownGracePeriodCriticalPods`:
* Specifies the duration used to terminate [critical pods](/docs/tasks/administer-cluster/guaranteed-scheduling-critical-addon-pods/#marking-pod-as-critical) during a node shutdown. This should be less than `ShutdownGracePeriod`.
For example, if `ShutdownGracePeriod=30s`, and `ShutdownGracePeriodCriticalPods=10s`, kubelet will delay the node shutdown by 30 seconds. During the shutdown, the first 20 (30-10) seconds would be reserved for gracefully terminating normal pods, and the last 10 seconds would be reserved for terminating [critical pods](/docs/tasks/administer-cluster/guaranteed-scheduling-critical-addon-pods/#marking-pod-as-critical).
* Specifies the duration used to terminate [critical pods](/docs/tasks/administer-cluster/guaranteed-scheduling-critical-addon-pods/#marking-pod-as-critical) during a node shutdown. This value should be less than `ShutdownGracePeriod`.
For example, if `ShutdownGracePeriod=30s`, and
`ShutdownGracePeriodCriticalPods=10s`, kubelet will delay the node shutdown by
30 seconds. During the shutdown, the first 20 (30-10) seconds would be reserved
for gracefully terminating normal pods, and the last 10 seconds would be
reserved for terminating [critical pods](/docs/tasks/administer-cluster/guaranteed-scheduling-critical-addon-pods/#marking-pod-as-critical).
## {{% heading "whatsnext" %}}

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content/en/docs/reference/command-line-tools-reference/feature-gates.md
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@ -120,7 +120,8 @@ different Kubernetes components.
| `ExperimentalHostUserNamespaceDefaulting` | `false` | Beta | 1.5 | |
| `GenericEphemeralVolume` | `false` | Alpha | 1.19 | 1.20 |
| `GenericEphemeralVolume` | `true` | Beta | 1.21 | |
| `GracefulNodeShutdown` | `false` | Alpha | 1.20 | |
| `GracefulNodeShutdown` | `false` | Alpha | 1.20 | 1.20 |
| `GracefulNodeShutdown` | `true` | Beta | 1.21 | |
| `HPAContainerMetrics` | `false` | Alpha | 1.20 | |
| `HPAScaleToZero` | `false` | Alpha | 1.16 | |
| `HugePageStorageMediumSize` | `false` | Alpha | 1.18 | 1.18 |