Chapter 17. Setting Quotas

A resource quota, defined by a ResourceQuota object, provides constraints that limit aggregate resource consumption per project. It can limit the quantity of objects that can be created in a project by type, as well as the total amount of compute resources and storage that may be consumed by resources in that project.

The following describes the set of compute resources and object types that may be managed by a quota.

Each quota can have an associated set of scopes. A quota will only measure usage for a resource if it matches the intersection of enumerated scopes.

Adding a scope to a quota restricts the set of resources to which that quota can apply. Specifying a resource outside of the allowed set results in a validation error.

A BestEffort scope restricts a quota to limiting the following resources:

A Terminating, NotTerminating, and NotBestEffort scope restricts a quota to tracking the following resources:

After a resource quota for a project is first created, the project restricts the ability to create any new resources that may violate a quota constraint until it has calculated updated usage statistics.

After a quota is created and usage statistics are updated, the project accepts the creation of new content. When you create or modify resources, your quota usage is incremented immediately upon the request to create or modify the resource.

When you delete a resource, your quota use is decremented during the next full recalculation of quota statistics for the project. A configurable amount of time determines how long it takes to reduce quota usage statistics to their current observed system value.

If project modifications exceed a quota usage limit, the server denies the action, and an appropriate error message is returned to the user explaining the quota constraint violated, and what their currently observed usage stats are in the system.

When allocating compute resources, each container may specify a request and a limit value each for CPU and memory. Quotas can restrict any of these values.

If the quota has a value specified for requests.cpu or requests.memory, then it requires that every incoming container make an explicit request for those resources. If the quota has a value specified for limits.cpu or limits.memory, then it requires that every incoming container specify an explicit limit for those resources.

To create a quota, first define the quota to your specifications in a file, for example as seen in Sample Resource Quota Definitions. Then, create using that file to apply it to a project:

$ oc create -f <resource_quota_definition> [-n <project_name>]

For example:

$ oc create -f resource-quota.json -n demoproject

You can view usage statistics related to any hard limits defined in a project’s quota by navigating in the web console to the project’s Quota page.

You can also use the CLI to view quota details:

When a set of resources are deleted, the synchronization time frame of resources is determined by the resource-quota-sync-period setting in the /etc/origin/master/master-config.yaml file.

Before quota usage is restored, a user may encounter problems when attempting to reuse the resources. You can change the resource-quota-sync-period setting to have the set of resources regenerate at the desired amount of time (in seconds) and for the resources to be available again:

kubernetesMasterConfig:
  apiLevels:
  - v1beta3
  - v1
  apiServerArguments: null
  controllerArguments:
    resource-quota-sync-period:
      - "10s"

After making any changes, restart the master services to apply them.

# systemctl restart atomic-openshift-master-api atomic-openshift-master-controllers

Adjusting the regeneration time can be helpful for creating resources and determining resource usage when automation is used.

If a quota has been defined for your project, see Deployment Resources for considerations on any deployment configurations.

If a resource is not managed by quota, a user has no restriction on the amount of resource that can be consumed. For example, if there is no quota on storage related to the gold storage class, the amount of gold storage a project can create is unbounded.

For high-cost compute or storage resources, administrators may want to require an explicit quota be granted in order to consume a resource. For example, if a project was not explicitly given quota for storage related to the gold storage class, users of that project would not be able to create any storage of that type.

In order to require explicit quota to consume a particular resource, the following stanza should be added to the master-config.yaml.

admissionConfig:
  pluginConfig:
    ResourceQuota:
      configuration:
        apiVersion: resourcequota.admission.k8s.io/v1alpha1
        kind: Configuration
        limitedResources:
        - resource: persistentvolumeclaims 1
        matchContains:
        - gold.storageclass.storage.k8s.io/requests.storage 2

In the above example, the quota system will intercept every operation that creates or updates a PersistentVolumeClaim. It checks what resources understood by quota would be consumed, and if there is no covering quota for those resources in the project, the request is denied. In this example, if a user creates a PersistentVolumeClaim that uses storage associated with the gold storage class, and there is no matching quota in the project, the request is denied.