This documentation is for a release that is no longer maintained
See documentation for the latest supported version 3 or the latest supported version 4.2.10. 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:
- 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.
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:
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
LimitRangeobject or configure limits inPodspecs for the overrides to apply.
Procedure
To install the Cluster Resource Override Operator using the OpenShift Container Platform web console:
In the OpenShift Container Platform web console, navigate to Home
Projects - Click Create Project.
-
Specify
clusterresourceoverride-operatoras the name of the project. - Click Create.
Navigate to Operators
OperatorHub. - Choose ClusterResourceOverride Operator from the list of available Operators and click Install.
- On the Install Operator page, make sure A specific Namespace on the cluster is selected for Installation Mode.
- Make sure clusterresourceoverride-operator is selected for Installed Namespace.
- Select an Update Channel and Approval Strategy.
- Click Install.
On the Installed Operators page, click ClusterResourceOverride.
- On the ClusterResourceOverride Operator details page, click Create Instance.
On the Create ClusterResourceOverride page, edit the YAML template to set the overcommit values as needed:
Copy to Clipboard Copied! Toggle word wrap Toggle overflow - 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.
- Click Create.
Check the current state of the admission webhook by checking the status of the cluster custom resource:
- On the ClusterResourceOverride Operator page, click cluster.
On the ClusterResourceOverride Details age, click YAML. The
mutatingWebhookConfigurationRefsection appears when the webhook is called.Copy to Clipboard Copied! Toggle word wrap Toggle overflow - 1
- Reference to the
ClusterResourceOverrideadmission 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
LimitRangeobject or configure limits inPodspecs for the overrides to apply.
Procedure
To install the Cluster Resource Override Operator using the CLI:
Create a namespace for the Cluster Resource Override Operator:
Create a
Namespaceobject YAML file (for example,cro-namespace.yaml) for the Cluster Resource Override Operator:apiVersion: v1 kind: Namespace metadata: name: clusterresourceoverride-operator
apiVersion: v1 kind: Namespace metadata: name: clusterresourceoverride-operatorCopy to Clipboard Copied! Toggle word wrap Toggle overflow Create the namespace:
oc create -f <file-name>.yaml
$ oc create -f <file-name>.yamlCopy to Clipboard Copied! Toggle word wrap Toggle overflow For example:
oc create -f cro-namespace.yaml
$ oc create -f cro-namespace.yamlCopy to Clipboard Copied! Toggle word wrap Toggle overflow
Create an Operator group:
Create an
OperatorGroupobject YAML file (for example, cro-og.yaml) for the Cluster Resource Override Operator:Copy to Clipboard Copied! Toggle word wrap Toggle overflow Create the Operator Group:
oc create -f <file-name>.yaml
$ oc create -f <file-name>.yamlCopy to Clipboard Copied! Toggle word wrap Toggle overflow For example:
oc create -f cro-og.yaml
$ oc create -f cro-og.yamlCopy to Clipboard Copied! Toggle word wrap Toggle overflow
Create a subscription:
Create a
Subscriptionobject YAML file (for example, cro-sub.yaml) for the Cluster Resource Override Operator:Copy to Clipboard Copied! Toggle word wrap Toggle overflow Create the subscription:
oc create -f <file-name>.yaml
$ oc create -f <file-name>.yamlCopy to Clipboard Copied! Toggle word wrap Toggle overflow For example:
oc create -f cro-sub.yaml
$ oc create -f cro-sub.yamlCopy to Clipboard Copied! Toggle word wrap Toggle overflow
Create a
ClusterResourceOverridecustom resource (CR) object in theclusterresourceoverride-operatornamespace:Change to the
clusterresourceoverride-operatornamespace.oc project clusterresourceoverride-operator
$ oc project clusterresourceoverride-operatorCopy to Clipboard Copied! Toggle word wrap Toggle overflow Create a
ClusterResourceOverrideobject YAML file (for example, cro-cr.yaml) for the Cluster Resource Override Operator:Copy to Clipboard Copied! Toggle word wrap Toggle overflow - 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.
Create the
ClusterResourceOverrideobject:oc create -f <file-name>.yaml
$ oc create -f <file-name>.yamlCopy to Clipboard Copied! Toggle word wrap Toggle overflow For example:
oc create -f cro-cr.yaml
$ oc create -f cro-cr.yamlCopy to Clipboard Copied! Toggle word wrap Toggle overflow
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
$ oc get clusterresourceoverride cluster -n clusterresourceoverride-operator -o yamlCopy to Clipboard Copied! Toggle word wrap Toggle overflow The
mutatingWebhookConfigurationRefsection appears when the webhook is called.Example output
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- Reference to the
ClusterResourceOverrideadmission webhook.
2.10.3. Configuring cluster-level overcommit 复制链接链接已复制到粘贴板!
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
LimitRangeobject or configure limits inPodspecs for the overrides to apply.
Procedure
To modify cluster-level overcommit:
Edit the
ClusterResourceOverrideCR:Copy to Clipboard Copied! Toggle word wrap Toggle overflow - 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.
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:
Copy to Clipboard Copied! Toggle word wrap Toggle overflow - 1
- Add this label to each project.