Documentation for in-place pod resize feature (#39845)
* Documentation for in-place pod resize feature Fix issues from review feedback Update content/en/docs/tasks/configure-pod-container/resize-container-resources.md Co-authored-by: Qiming Teng <tengqm@outlook.com> Better wording and formatting of overview section Add descriptions about allocatedResources, resources, and resize fields Update content/en/docs/tasks/configure-pod-container/resize-container-resources.md Co-authored-by: Qiming Teng <tengqm@outlook.com> Update content/en/docs/tasks/configure-pod-container/resize-container-resources.md Co-authored-by: Qiming Teng <tengqm@outlook.com> Apply suggestions from code review Co-authored-by: Qiming Teng <tengqm@outlook.com> * Simplify the changes by using bullet points * Apply suggestions from code review Co-authored-by: Tim Bannister <tim@scalefactory.com> --------- Co-authored-by: Qiming Teng <tengqm@outlook.com> Co-authored-by: Tim Bannister <tim@scalefactory.com>pull/40064/head
Vinay Kulkarni
GitHub
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@ -275,4 +275,4 @@ kubectl delete namespace cpu-example
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* [Configure Quotas for API Objects](/docs/tasks/administer-cluster/quota-api-object/)
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* [Resize CPU and Memory Resources assigned to Containers](/docs/tasks/configure-pod-container/resize-container-resources/)
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@ -358,7 +358,4 @@ kubectl delete namespace mem-example
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* [Configure Quotas for API Objects](/docs/tasks/administer-cluster/quota-api-object/)
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* [Resize CPU and Memory Resources assigned to Containers](/docs/tasks/configure-pod-container/resize-container-resources/)
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---
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title: Resize CPU and Memory Resources assigned to Containers
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content_type: task
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weight: 30
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min-kubernetes-server-version: 1.27
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---
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<!-- overview -->
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{{< feature-state state="alpha" for_k8s_version="v1.27" >}}
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This page assumes that you are familiar with [Quality of Service](/docs/tasks/configure-pod-container/quality-service-pod/)
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for Kubernetes Pods.
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This page shows how to resize CPU and memory resources assigned to containers
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of a running pod without restarting the pod or its containers. A Kubernetes node
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allocates resources for a pod based on its `requests`, and restricts the pod's
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resource usage based on the `limits` specified in the pod's containers.
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For in-place resize of pod resources:
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- Container's resource `requests` and `limits` are _mutable_ for CPU
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and memory resources.
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- `allocatedResources` field in `containerStatuses` of the Pod's status reflects
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the resources allocated to the pod's containers.
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- `resources` field in `containerStatuses` of the Pod's status reflects the
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actual resource `requests` and `limits` that are configured on the running
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containers as reported by the container runtime.
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- `resize` field in the Pod's status shows the status of the last requested
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pending resize. It can have the following values:
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- `Proposed`: This value indicates an acknowledgement of the requested resize
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and that the request was validated and recorded.
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- `InProgress`: This value indicates that the node has accepted the resize
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request and is in the process of applying it to the pod's containers.
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- `Deferred`: This value means that the requested resize cannot be granted at
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this time, and the node will keep retrying. The resize may be granted when
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other pods leave and free up node resources.
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- `Infeasible`: is a signal that the node cannot accommodate the requested
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resize. This can happen if the requested resize exceeds the maximum
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resources the node can ever allocate for a pod.
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## {{% heading "prerequisites" %}}
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{{< include "task-tutorial-prereqs.md" >}} {{< version-check >}}
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## Container Resize Policies
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Resize policies allow for a more fine-grained control over how pod's containers
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are resized for CPU and memory resources. For example, the container's
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application may be able to handle CPU resources resized without being restarted,
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but resizing memory may require that the application hence the containers be restarted.
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To enable this, the Container specification allows users to specify a `resizePolicy`.
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The following restart policies can be specified for resizing CPU and memory:
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* `NotRequired`: Resize the container's resources while it is running.
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* `RestartContainer`: Restart the container and apply new resources upon restart.
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If `resizePolicy[*].restartPolicy` is not specified, it defaults to `NotRequired`.
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{{< note >}}
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If the Pod's `restartPolicy` is `Never`, container's resize restart policy must be
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set to `NotRequired` for all Containers in the Pod.
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{{< /note >}}
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Below example shows a Pod whose Container's CPU can be resized without restart, but
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memory resize memory requires the container to be restarted.
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```yaml
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apiVersion: v1
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kind: Pod
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metadata:
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name: qos-demo-5
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namespace: qos-example
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spec:
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containers:
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- name: qos-demo-ctr-5
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image: nginx
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resizePolicy:
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- resourceName: cpu
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restartPolicy: NotRequired
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- resourceName: memory
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restartPolicy: RestartContainer
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resources:
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limits:
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memory: "200Mi"
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cpu: "700m"
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requests:
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memory: "200Mi"
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cpu: "700m"
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```
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{{< note >}}
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In the above example, if desired requests or limits for both CPU _and_ memory
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have changed, the container will be restarted in order to resize its memory.
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{{< /note >}}
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<!-- steps -->
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## Create a pod with resource requests and limits
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You can create a Guaranteed or Burstable [Quality of Service](/docs/tasks/configure-pod-container/quality-service-pod/)
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class pod by specifying requests and/or limits for a pod's containers.
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Consider the following manifest for a Pod that has one Container.
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{{< codenew file="pods/qos/qos-pod-5.yaml" >}}
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Create the pod in the `qos-example` namespace:
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```shell
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kubectl create namespace qos-example
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kubectl create -f https://k8s.io/examples/pods/qos/qos-pod-5.yaml
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```
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This pod is classified as a Guaranteed QoS class requesting 700m CPU and 200Mi
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memory.
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View detailed information about the pod:
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```shell
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kubectl get pod qos-demo-5 --output=yaml --namespace=qos-example
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```
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Also notice that the values of `resizePolicy[*].restartPolicy` defaulted to
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`NotRequired`, indicating that CPU and memory can be resized while container
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is running.
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```yaml
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spec:
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containers:
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...
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resizePolicy:
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- resourceName: cpu
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restartPolicy: NotRequired
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- resourceName: memory
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restartPolicy: NotRequired
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resources:
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limits:
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cpu: 700m
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memory: 200Mi
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requests:
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cpu: 700m
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memory: 200Mi
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...
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containerStatuses:
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...
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name: qos-demo-ctr-5
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ready: true
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...
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allocatedResources:
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cpu: 700m
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memory: 200Mi
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resources:
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limits:
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cpu: 700m
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memory: 200Mi
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requests:
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cpu: 700m
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memory: 200Mi
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restartCount: 0
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started: true
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...
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qosClass: Guaranteed
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```
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## Updating the pod's resources
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Let's say the CPU requirements have increased, and 0.8 CPU is now desired. This
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is typically determined, and may be programmatically applied, by an entity such as
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[VerticalPodAutoscaler](https://github.com/kubernetes/autoscaler/tree/master/vertical-pod-autoscaler#readme) (VPA).
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{{< note >}}
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While you can change a Pod's requests and limits to express new desired
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resources, you cannot change the QoS class in which the Pod was created.
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{{< /note >}}
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Now, patch the Pod's Container with CPU requests & limits both set to `800m`:
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```shell
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kubectl -n qos-example patch pod qos-demo-5 --patch '{"spec":{"containers":[{"name":"qos-demo-ctr-5", "resources":{"requests":{"cpu":"800m"}, "limits":{"cpu":"800m"}}}]}}'
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```
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Query the Pod's detailed information after the Pod has been patched.
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```shell
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kubectl get pod qos-demo-5 --output=yaml --namespace=qos-example
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```
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The Pod's spec below reflects the updated CPU requests and limits.
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```yaml
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spec:
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containers:
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...
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resources:
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limits:
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cpu: 800m
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memory: 200Mi
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requests:
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cpu: 800m
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memory: 200Mi
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...
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containerStatuses:
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...
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allocatedResources:
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cpu: 800m
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memory: 200Mi
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resources:
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limits:
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cpu: 800m
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memory: 200Mi
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requests:
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cpu: 800m
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memory: 200Mi
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restartCount: 0
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started: true
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```
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Observe that the `allocatedResources` values have been updated to reflect the new
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desired CPU requests. This indicates that node was able to accommodate the
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increased CPU resource needs.
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In the Container's status, updated CPU resource values shows that new CPU
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resources have been applied. The Container's `restartCount` remains unchanged,
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indicating that container's CPU resources were resized without restarting the container.
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## Clean up
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Delete your namespace:
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```shell
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kubectl delete namespace qos-example
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```
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## {{% heading "whatsnext" %}}
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### For application developers
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* [Assign Memory Resources to Containers and Pods](/docs/tasks/configure-pod-container/assign-memory-resource/)
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* [Assign CPU Resources to Containers and Pods](/docs/tasks/configure-pod-container/assign-cpu-resource/)
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### For cluster administrators
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* [Configure Default Memory Requests and Limits for a Namespace](/docs/tasks/administer-cluster/manage-resources/memory-default-namespace/)
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* [Configure Default CPU Requests and Limits for a Namespace](/docs/tasks/administer-cluster/manage-resources/cpu-default-namespace/)
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* [Configure Minimum and Maximum Memory Constraints for a Namespace](/docs/tasks/administer-cluster/manage-resources/memory-constraint-namespace/)
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* [Configure Minimum and Maximum CPU Constraints for a Namespace](/docs/tasks/administer-cluster/manage-resources/cpu-constraint-namespace/)
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* [Configure Memory and CPU Quotas for a Namespace](/docs/tasks/administer-cluster/manage-resources/quota-memory-cpu-namespace/)
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@ -0,0 +1,16 @@
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apiVersion: v1
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kind: Pod
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metadata:
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name: qos-demo-5
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namespace: qos-example
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spec:
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containers:
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- name: qos-demo-ctr-5
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image: nginx
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resources:
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limits:
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memory: "200Mi"
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cpu: "700m"
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requests:
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memory: "200Mi"
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cpu: "700m"
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