Merge pull request #28407 from tengqm/fix-links
Fix some links in the concepts section
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@@ -10,7 +10,8 @@ weight: 40
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{{< feature-state for_k8s_version="v1.20" state="stable" >}}
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Kubernetes allow you to limit the number of process IDs (PIDs) that a {{< glossary_tooltip term_id="Pod" text="Pod" >}} can use.
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Kubernetes allow you to limit the number of process IDs (PIDs) that a
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{{< glossary_tooltip term_id="Pod" text="Pod" >}} can use.
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You can also reserve a number of allocatable PIDs for each {{< glossary_tooltip term_id="node" text="node" >}}
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for use by the operating system and daemons (rather than by Pods).
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@@ -84,7 +85,9 @@ gate](/docs/reference/command-line-tools-reference/feature-gates/)
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Kubernetes allows you to limit the number of processes running in a Pod. You
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specify this limit at the node level, rather than configuring it as a resource
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limit for a particular Pod. Each Node can have a different PID limit.
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To configure the limit, you can specify the command line parameter `--pod-max-pids` to the kubelet, or set `PodPidsLimit` in the kubelet [configuration file](/docs/tasks/administer-cluster/kubelet-config-file/).
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To configure the limit, you can specify the command line parameter `--pod-max-pids`
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to the kubelet, or set `PodPidsLimit` in the kubelet
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[configuration file](/docs/tasks/administer-cluster/kubelet-config-file/).
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{{< note >}}
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Before Kubernetes version 1.20, PID resource limiting for Pods required enabling
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@@ -95,9 +98,12 @@ the [feature gate](/docs/reference/command-line-tools-reference/feature-gates/)
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## PID based eviction
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You can configure kubelet to start terminating a Pod when it is misbehaving and consuming abnormal amount of resources.
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This feature is called eviction. You can [Configure Out of Resource Handling](/docs/tasks/administer-cluster/out-of-resource) for various eviction signals.
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This feature is called eviction. You can
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[Configure Out of Resource Handling](/docs/concepts/scheduling-eviction/node-pressure-eviction/)
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for various eviction signals.
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Use `pid.available` eviction signal to configure the threshold for number of PIDs used by Pod.
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You can set soft and hard eviction policies. However, even with the hard eviction policy, if the number of PIDs growing very fast,
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You can set soft and hard eviction policies.
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However, even with the hard eviction policy, if the number of PIDs growing very fast,
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node can still get into unstable state by hitting the node PIDs limit.
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Eviction signal value is calculated periodically and does NOT enforce the limit.
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@@ -112,6 +118,7 @@ when one Pod is misbehaving.
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## {{% heading "whatsnext" %}}
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- Refer to the [PID Limiting enhancement document](https://github.com/kubernetes/enhancements/blob/097b4d8276bc9564e56adf72505d43ce9bc5e9e8/keps/sig-node/20190129-pid-limiting.md) for more information.
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- For historical context, read [Process ID Limiting for Stability Improvements in Kubernetes 1.14](/blog/2019/04/15/process-id-limiting-for-stability-improvements-in-kubernetes-1.14/).
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- For historical context, read
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[Process ID Limiting for Stability Improvements in Kubernetes 1.14](/blog/2019/04/15/process-id-limiting-for-stability-improvements-in-kubernetes-1.14/).
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- Read [Managing Resources for Containers](/docs/concepts/configuration/manage-resources-containers/).
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- Learn how to [Configure Out of Resource Handling](/docs/tasks/administer-cluster/out-of-resource).
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- Learn how to [Configure Out of Resource Handling](/docs/concepts/scheduling-eviction/node-pressure-eviction/).
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@@ -57,8 +57,9 @@ Neither contention nor changes to quota will affect already created resources.
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## Enabling Resource Quota
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Resource Quota support is enabled by default for many Kubernetes distributions. It is
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enabled when the {{< glossary_tooltip text="API server" term_id="kube-apiserver" >}} `--enable-admission-plugins=` flag has `ResourceQuota` as
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Resource Quota support is enabled by default for many Kubernetes distributions. It is
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enabled when the {{< glossary_tooltip text="API server" term_id="kube-apiserver" >}}
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`--enable-admission-plugins=` flag has `ResourceQuota` as
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one of its arguments.
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A resource quota is enforced in a particular namespace when there is a
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@@ -66,7 +67,9 @@ ResourceQuota in that namespace.
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## Compute Resource Quota
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You can limit the total sum of [compute resources](/docs/concepts/configuration/manage-resources-containers/) that can be requested in a given namespace.
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You can limit the total sum of
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[compute resources](/docs/concepts/configuration/manage-resources-containers/)
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that can be requested in a given namespace.
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The following resource types are supported:
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@@ -125,7 +128,9 @@ In release 1.8, quota support for local ephemeral storage is added as an alpha f
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| `ephemeral-storage` | Same as `requests.ephemeral-storage`. |
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{{< note >}}
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When using a CRI container runtime, container logs will count against the ephemeral storage quota. This can result in the unexpected eviction of pods that have exhausted their storage quotas. Refer to [Logging Architecture](/docs/concepts/cluster-administration/logging/) for details.
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When using a CRI container runtime, container logs will count against the ephemeral storage quota.
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This can result in the unexpected eviction of pods that have exhausted their storage quotas.
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Refer to [Logging Architecture](/docs/concepts/cluster-administration/logging/) for details.
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{{< /note >}}
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## Object Count Quota
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@@ -192,7 +197,7 @@ Resources specified on the quota outside of the allowed set results in a validat
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| `NotTerminating` | Match pods where `.spec.activeDeadlineSeconds is nil` |
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| `BestEffort` | Match pods that have best effort quality of service. |
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| `NotBestEffort` | Match pods that do not have best effort quality of service. |
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| `PriorityClass` | Match pods that references the specified [priority class](/docs/concepts/configuration/pod-priority-preemption). |
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| `PriorityClass` | Match pods that references the specified [priority class](/docs/concepts/scheduling-eviction/pod-priority-preemption). |
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| `CrossNamespacePodAffinity` | Match pods that have cross-namespace pod [(anti)affinity terms](/docs/concepts/scheduling-eviction/assign-pod-node). |
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The `BestEffort` scope restricts a quota to tracking the following resource:
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@@ -248,13 +253,14 @@ specified.
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{{< feature-state for_k8s_version="v1.17" state="stable" >}}
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Pods can be created at a specific [priority](/docs/concepts/configuration/pod-priority-preemption/#pod-priority).
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Pods can be created at a specific [priority](/docs/concepts/scheduling-eviction/pod-priority-preemption/#pod-priority).
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You can control a pod's consumption of system resources based on a pod's priority, by using the `scopeSelector`
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field in the quota spec.
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A quota is matched and consumed only if `scopeSelector` in the quota spec selects the pod.
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When quota is scoped for priority class using `scopeSelector` field, quota object is restricted to track only following resources:
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When quota is scoped for priority class using `scopeSelector` field, quota object
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is restricted to track only following resources:
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* `pods`
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* `cpu`
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@@ -554,7 +560,7 @@ kubectl create -f ./object-counts.yaml --namespace=myspace
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kubectl get quota --namespace=myspace
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```
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```
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```none
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NAME AGE
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compute-resources 30s
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object-counts 32s
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@@ -564,7 +570,7 @@ object-counts 32s
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kubectl describe quota compute-resources --namespace=myspace
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```
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```
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```none
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Name: compute-resources
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Namespace: myspace
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Resource Used Hard
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@@ -580,7 +586,7 @@ requests.nvidia.com/gpu 0 4
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kubectl describe quota object-counts --namespace=myspace
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```
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```
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```none
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Name: object-counts
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Namespace: myspace
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Resource Used Hard
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@@ -677,10 +683,10 @@ Then, create a resource quota object in the `kube-system` namespace:
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{{< codenew file="policy/priority-class-resourcequota.yaml" >}}
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```shell
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$ kubectl apply -f https://k8s.io/examples/policy/priority-class-resourcequota.yaml -n kube-system
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kubectl apply -f https://k8s.io/examples/policy/priority-class-resourcequota.yaml -n kube-system
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```
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```
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```none
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resourcequota/pods-cluster-services created
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```
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