Overview

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 that may be consumed by resources in that project.

See the Developer Guide for more on compute resources.

Resources Managed by Quota

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

Table 1. Compute Resources Managed by Quota
Resource Name Description

cpu

Across all pods in a non-terminal state, the sum of CPU requests cannot exceed this value. cpu and `requests.cpu`are the same value and can be used interchangeably.

memory

Across all pods in a non-terminal state, the sum of memory requests cannot exceed this value. memory and requests.memory are the same value and can be used interchangeably.

requests.cpu

Across all pods in a non-terminal state, the sum of CPU requests cannot exceed this value. cpu and `requests.cpu`are the same value and can be used interchangeably.

requests.memory

Across all pods in a non-terminal state, the sum of memory requests cannot exceed this value. memory and requests.memory are the same value and can be used interchangeably.

limits.cpu

Across all pods in a non-terminal state, the sum of CPU limits cannot exceed this value.

limits.memory

Across all pods in a non-terminal state, the sum of memory limits cannot exceed this value.

Table 2. Object Counts Managed by Quota
Resource Name Description

pods

The total number of pods in a non-terminal state that can exist in the project. A pod is in a terminal state if status.phase in (Failed, Succeeded) is true.

replicationcontrollers

The total number of replication controllers that can exist in the project.

resourcequotas

The total number of resource quotas that can exist in the project.

services

The total number of services that can exist in the project.

secrets

The total number of secrets that can exist in the project.

configmaps

The total number of ConfigMap objects that can exist in the project.

persistentvolumeclaims

The total number of persistent volume claims that can exist in the project.

openshift.io/imagestreams

The total number of image streams that can exist in the project.

Quota Scopes

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.

When a scope is added to a quota, it limits the number of resources it supports to those that pertain to the scope. Resources specified on the quota outside of the allowed set results in a validation error.

Scope Description

Terminating

Match pods where spec.activeDeadlineSeconds >= 0

NotTerminating

Match pods where spec.activeDeadlineSeconds is nil

BestEffort

Match pods that have best effort quality of service for either cpu or memory.

NotBestEffort

Match pods that do not have best effort quality of service for cpu and memory.

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

  • pods

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

  • pods

  • memory

  • requests.memory

  • limits.memory

  • cpu

  • requests.cpu

  • limits.cpu

Quota Enforcement

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.

Requests vs Limits

When allocating compute resources, each container may specify a request and a limit value for either CPU or memory. The quota can be configured to quota either value.

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

Sample Resource Quota Definitions

Example 1. object-counts.yaml
apiVersion: v1
kind: ResourceQuota
metadata:
  name: core-object-counts
spec:
  hard:
    configmaps: "10" (1)
    persistentvolumeclaims: "4" (2)
    replicationcontrollers: "20" (3)
    secrets: "10" (4)
    services: "10" (5)
1 The total number of ConfigMap objects that can exist in the project.
2 The total number of persistent volume claims (PVCs) that can exist in the project.
3 The total number of replication controllers that can exist in the project.
4 The total number of secrets that can exist in the project.
5 The total number of services that can exist in the project.
Example 2. openshift-object-counts.yaml
apiVersion: v1
kind: ResourceQuota
metadata:
  name: openshift-object-counts
spec:
  hard:
    openshift.io/imagestreams: "10" (1)
1 The total number of image streams that can exist in the project.
Example 3. compute-resources.yaml
apiVersion: v1
kind: ResourceQuota
metadata:
  name: compute-resources
spec:
  hard:
    pods: "4" (1)
    requests.cpu: "1" (2)
    requests.memory: 1Gi (3)
    limits.cpu: "2" (4)
    limits.memory: 2Gi  (5)
1 The total number of pods in a non-terminal state that can exist in the project.
2 Across all pods in a non-terminal state, the sum of CPU requests cannot exceed 1 core.
3 Across all pods in a non-terminal state, the sum of memory requests cannot exceed 1Gi.
4 Across all pods in a non-terminal state, the sum of CPU limits cannot exceed 2 cores.
5 Across all pods in a non-terminal state, the sum of memory limits cannot exceed 2Gi.
Example 4. besteffort.yaml
apiVersion: v1
kind: ResourceQuota
metadata:
  name: besteffort
spec:
  hard:
    pods: "1" (1)
  scopes:
  - BestEffort  (2)
1 The total number of pods in a non-terminal state with BestEffort quality of service that can exist in the project.
2 Restricts the quota to only matching pods that have BestEffort quality of service for either memory or CPU.
Example 5. compute-resources-long-running.yaml
apiVersion: v1
kind: ResourceQuota
metadata:
  name: compute-resources-long-running
spec:
  hard:
    pods: "4" (1)
    limits.cpu: "4" (2)
    limits.memory: "2Gi" (3)
  scopes:
  - NotTerminating (4)
1 The total number of pods in a non-terminal state.
2 Across all pods in a non-terminal state, the sum of CPU limits cannot exceed this value.
3 Across all pods in a non-terminal state, the sum of memory limits cannot exceed this value.
4 Restricts the quota to only matching pods where spec.activeDeadlineSeconds is nil. For example, this quota would not charge for build or deployer pods.
Example 6. compute-resources-time-bound.yaml
apiVersion: v1
kind: ResourceQuota
metadata:
  name: compute-resources-time-bound
spec:
  hard:
    pods: "2" (1)
    limits.cpu: "1" (2)
    limits.memory: "1Gi" (3)
  scopes:
  - Terminating (4)
1 The total number of pods in a non-terminal state.
2 Across all pods in a non-terminal state, the sum of CPU limits cannot exceed this value.
3 Across all pods in a non-terminal state, the sum of memory limits cannot exceed this value.
4 Restricts the quota to only matching pods where spec.activeDeadlineSeconds >=0. For example, this quota would charge for build or deployer pods, but not long running pods like a web server or database.

Creating a Quota

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

Viewing a Quota

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 Settings tab.

You can also use the CLI to view quota details:

  1. First, get the list of quotas defined in the project. For example, for a project called demoproject:

    $ oc get quota -n demoproject
    NAME                AGE
    besteffort          11m
    compute-resources   2m
    core-object-counts  29m
  2. Then, describe the quota you are interested in, for example the core-object-counts quota:

    $ oc describe quota core-object-counts -n demoproject
    Name:			core-object-counts
    Namespace:		demoproject
    Resource		Used	Hard
    --------		----	----
    configmaps		3	10
    persistentvolumeclaims	0	4
    replicationcontrollers	3	20
    secrets			9	10
    services		2	10

Configuring Quota Synchronization Period

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 service to apply them.

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

The resource-quota-sync-period setting is designed to balance system performance. Reducing the sync period can result in a heavy load on the master.

Accounting for Quota in Deployment Configurations

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