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2.10. Cluster-level overcommit using the Cluster Resource Override Operator

The Cluster Resource Override Operator is an admission webhook that allows you to control the level of overcommit and manage container density across all the nodes in your cluster. The Operator controls how nodes in specific projects can exceed defined memory and CPU limits.

You must install the Cluster Resource Override Operator using the OpenShift Container Platform console or CLI as shown in the following sections. During the installation, you create a ClusterResourceOverride custom resource (CR), where you set the level of overcommit, as shown in the following example: 

apiVersion: operator.autoscaling.openshift.io/v1
kind: ClusterResourceOverride
metadata:
-   name: cluster
1 

spec:
   memoryRequestToLimitPercent: 50
2 

   cpuRequestToLimitPercent: 25
3 

   limitCPUToMemoryPercent: 200
4
Copy to Clipboard Toggle word wrap
1
The name must be cluster.
2
Optional. If a container memory limit has been specified or defaulted, the memory request is overridden to this percentage of the limit, between 1-100. The default is 50.
3
Optional. If a container CPU limit has been specified or defaulted, the CPU request is overridden to this percentage of the limit, between 1-100. The default is 25.
4
Optional. If a container memory limit has been specified or defaulted, the CPU limit is overridden to a percentage of the memory limit, if specified. Scaling 1Gi of RAM at 100 percent is equal to 1 CPU core. This is processed prior to overriding the CPU request (if configured). The default is 200.
注意

The Cluster Resource Override Operator overrides have no effect if limits have not been set on containers. Create a LimitRange object with default limits per individual project or configure limits in Pod specs for the overrides to apply.

When configured, overrides can be enabled per-project by applying the following label to the Namespace object for each project: 

apiVersion: v1
kind: Namespace
metadata:

....

  labels:
    clusterresourceoverrides.admission.autoscaling.openshift.io/enabled: "true"

....
Copy to Clipboard Toggle word wrap

The Operator watches for the ClusterResourceOverride CR and ensures that the ClusterResourceOverride admission webhook is installed into the same namespace as the operator.

You can use the OpenShift Container Platform web console to install the Cluster Resource Override Operator to help control overcommit in your cluster.

Prerequisites

  • The Cluster Resource Override Operator has no effect if limits have not been set on containers. You must specify default limits for a project using a LimitRange object or configure limits in Pod specs for the overrides to apply.

Procedure

To install the Cluster Resource Override Operator using the OpenShift Container Platform web console:

  1. In the OpenShift Container Platform web console, navigate to Home Projects

    1. Click Create Project.
    2. Specify clusterresourceoverride-operator as the name of the project.
    3. Click Create.

  2. Navigate to Operators OperatorHub.

    1. Choose ClusterResourceOverride Operator from the list of available Operators and click Install.
    2. On the Install Operator page, make sure A specific Namespace on the cluster is selected for Installation Mode.
    3. Make sure clusterresourceoverride-operator is selected for Installed Namespace.
    4. Select an Update Channel and Approval Strategy.
    5. Click Install.

  3. On the Installed Operators page, click ClusterResourceOverride.

    1. On the ClusterResourceOverride Operator details page, click Create Instance.

    2. On the Create ClusterResourceOverride page, edit the YAML template to set the overcommit values as needed: 

      apiVersion: operator.autoscaling.openshift.io/v1
kind: ClusterResourceOverride
metadata:
  name: cluster
      1 
      
spec:
  podResourceOverride:
    spec:
      memoryRequestToLimitPercent: 50
      2 
      
      cpuRequestToLimitPercent: 25
      3 
      
      limitCPUToMemoryPercent: 200
      4
      Copy to Clipboard Toggle word wrap
      1
      The name must be cluster.
      2
      Optional. Specify the percentage to override the container memory limit, if used, between 1-100. The default is 50.
      3
      Optional. Specify the percentage to override the container CPU limit, if used, between 1-100. The default is 25.
      4
      Optional. Specify the percentage to override the container memory limit, if used. Scaling 1Gi of RAM at 100 percent is equal to 1 CPU core. This is processed prior to overriding the CPU request, if configured. The default is 200.
    3. Click Create.

  4. Check the current state of the admission webhook by checking the status of the cluster custom resource:

    1. On the ClusterResourceOverride Operator page, click cluster.

    2. On the ClusterResourceOverride Details age, click YAML. The mutatingWebhookConfigurationRef section appears when the webhook is called. 

      apiVersion: operator.autoscaling.openshift.io/v1
kind: ClusterResourceOverride
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"operator.autoscaling.openshift.io/v1","kind":"ClusterResourceOverride","metadata":{"annotations":{},"name":"cluster"},"spec":{"podResourceOverride":{"spec":{"cpuRequestToLimitPercent":25,"limitCPUToMemoryPercent":200,"memoryRequestToLimitPercent":50}}}}
  creationTimestamp: "2019-12-18T22:35:02Z"
  generation: 1
  name: cluster
  resourceVersion: "127622"
  selfLink: /apis/operator.autoscaling.openshift.io/v1/clusterresourceoverrides/cluster
  uid: 978fc959-1717-4bd1-97d0-ae00ee111e8d
spec:
  podResourceOverride:
    spec:
      cpuRequestToLimitPercent: 25
      limitCPUToMemoryPercent: 200
      memoryRequestToLimitPercent: 50
status:

....

    mutatingWebhookConfigurationRef:
      1 
      
      apiVersion: admissionregistration.k8s.io/v1beta1
      kind: MutatingWebhookConfiguration
      name: clusterresourceoverrides.admission.autoscaling.openshift.io
      resourceVersion: "127621"
      uid: 98b3b8ae-d5ce-462b-8ab5-a729ea8f38f3

....
      Copy to Clipboard Toggle word wrap
      1
      Reference to the ClusterResourceOverride admission webhook.

You can use the OpenShift Container Platform CLI to install the Cluster Resource Override Operator to help control overcommit in your cluster.

Prerequisites

  • The Cluster Resource Override Operator has no effect if limits have not been set on containers. You must specify default limits for a project using a LimitRange object or configure limits in Pod specs for the overrides to apply.

Procedure

To install the Cluster Resource Override Operator using the CLI:

  1. Create a namespace for the Cluster Resource Override Operator:

    1. Create a Namespace object YAML file (for example, cro-namespace.yaml) for the Cluster Resource Override Operator: 

      apiVersion: v1
kind: Namespace
metadata:
  name: clusterresourceoverride-operator
      Copy to Clipboard Toggle word wrap

    2. Create the namespace: 

      $ oc create -f <file-name>.yaml
      Copy to Clipboard Toggle word wrap

      For example: 

      $ oc create -f cro-namespace.yaml
      Copy to Clipboard Toggle word wrap

  2. Create an Operator group:

    1. Create an OperatorGroup object YAML file (for example, cro-og.yaml) for the Cluster Resource Override Operator: 

      apiVersion: operators.coreos.com/v1
kind: OperatorGroup
metadata:
  name: clusterresourceoverride-operator
  namespace: clusterresourceoverride-operator
spec:
  targetNamespaces:
    - clusterresourceoverride-operator
      Copy to Clipboard Toggle word wrap

    2. Create the Operator Group: 

      $ oc create -f <file-name>.yaml
      Copy to Clipboard Toggle word wrap

      For example: 

      $ oc create -f cro-og.yaml
      Copy to Clipboard Toggle word wrap

  3. Create a subscription:

    1. Create a Subscription object YAML file (for example, cro-sub.yaml) for the Cluster Resource Override Operator: 

      apiVersion: operators.coreos.com/v1alpha1
kind: Subscription
metadata:
  name: clusterresourceoverride
  namespace: clusterresourceoverride-operator
spec:
  channel: "4.5"
  name: clusterresourceoverride
  source: redhat-operators
  sourceNamespace: openshift-marketplace
      Copy to Clipboard Toggle word wrap

    2. Create the subscription: 

      $ oc create -f <file-name>.yaml
      Copy to Clipboard Toggle word wrap

      For example: 

      $ oc create -f cro-sub.yaml
      Copy to Clipboard Toggle word wrap

  4. Create a ClusterResourceOverride custom resource (CR) object in the clusterresourceoverride-operator namespace:

    1. Change to the clusterresourceoverride-operator namespace. 

      $ oc project clusterresourceoverride-operator
      Copy to Clipboard Toggle word wrap

    2. Create a ClusterResourceOverride object YAML file (for example, cro-cr.yaml) for the Cluster Resource Override Operator: 

      apiVersion: operator.autoscaling.openshift.io/v1
kind: ClusterResourceOverride
metadata:
    name: cluster
      1 
      
spec:
  podResourceOverride:
    spec:
      memoryRequestToLimitPercent: 50
      2 
      
      cpuRequestToLimitPercent: 25
      3 
      
      limitCPUToMemoryPercent: 200
      4
      Copy to Clipboard Toggle word wrap
      1
      The name must be cluster.
      2
      Optional. Specify the percentage to override the container memory limit, if used, between 1-100. The default is 50.
      3
      Optional. Specify the percentage to override the container CPU limit, if used, between 1-100. The default is 25.
      4
      Optional. Specify the percentage to override the container memory limit, if used. Scaling 1Gi of RAM at 100 percent is equal to 1 CPU core. This is processed prior to overriding the CPU request, if configured. The default is 200.

    3. Create the ClusterResourceOverride object: 

      $ oc create -f <file-name>.yaml
      Copy to Clipboard Toggle word wrap

      For example: 

      $ oc create -f cro-cr.yaml
      Copy to Clipboard Toggle word wrap

  5. Verify the current state of the admission webhook by checking the status of the cluster custom resource. 

    $ oc get clusterresourceoverride cluster -n clusterresourceoverride-operator -o yaml
    Copy to Clipboard Toggle word wrap

    The mutatingWebhookConfigurationRef section appears when the webhook is called.

    Example output

    apiVersion: operator.autoscaling.openshift.io/v1
kind: ClusterResourceOverride
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"operator.autoscaling.openshift.io/v1","kind":"ClusterResourceOverride","metadata":{"annotations":{},"name":"cluster"},"spec":{"podResourceOverride":{"spec":{"cpuRequestToLimitPercent":25,"limitCPUToMemoryPercent":200,"memoryRequestToLimitPercent":50}}}}
  creationTimestamp: "2019-12-18T22:35:02Z"
  generation: 1
  name: cluster
  resourceVersion: "127622"
  selfLink: /apis/operator.autoscaling.openshift.io/v1/clusterresourceoverrides/cluster
  uid: 978fc959-1717-4bd1-97d0-ae00ee111e8d
spec:
  podResourceOverride:
    spec:
      cpuRequestToLimitPercent: 25
      limitCPUToMemoryPercent: 200
      memoryRequestToLimitPercent: 50
status:

....

    mutatingWebhookConfigurationRef:
    1 
    
      apiVersion: admissionregistration.k8s.io/v1beta1
      kind: MutatingWebhookConfiguration
      name: clusterresourceoverrides.admission.autoscaling.openshift.io
      resourceVersion: "127621"
      uid: 98b3b8ae-d5ce-462b-8ab5-a729ea8f38f3

....
    Copy to Clipboard Toggle word wrap

    1
    Reference to the ClusterResourceOverride admission webhook.

2.10.3. Configuring cluster-level overcommit
复制链接

The Cluster Resource Override Operator requires a ClusterResourceOverride custom resource (CR) and a label for each project where you want the Operator to control overcommit.

Prerequisites

  • The Cluster Resource Override Operator has no effect if limits have not been set on containers. You must specify default limits for a project using a LimitRange object or configure limits in Pod specs for the overrides to apply.

Procedure

To modify cluster-level overcommit:

  1. Edit the ClusterResourceOverride CR: 

    apiVersion: operator.autoscaling.openshift.io/v1
kind: ClusterResourceOverride
metadata:
-   name: cluster
spec:
   memoryRequestToLimitPercent: 50
    1 
    
   cpuRequestToLimitPercent: 25
    2 
    
   limitCPUToMemoryPercent: 200
    3
    Copy to Clipboard Toggle word wrap
    1
    Optional. Specify the percentage to override the container memory limit, if used, between 1-100. The default is 50.
    2
    Optional. Specify the percentage to override the container CPU limit, if used, between 1-100. The default is 25.
    3
    Optional. Specify the percentage to override the container memory limit, if used. Scaling 1Gi of RAM at 100 percent is equal to 1 CPU core. This is processed prior to overriding the CPU request, if configured. The default is 200.

  2. Ensure the following label has been added to the Namespace object for each project where you want the Cluster Resource Override Operator to control overcommit: 

    apiVersion: v1
kind: Namespace
metadata:

....

  labels:
    clusterresourceoverrides.admission.autoscaling.openshift.io/enabled: "true"
    1 
    

....
    Copy to Clipboard Toggle word wrap
    1
    Add this label to each project.
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