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.

This guide describes how resource quotas work, how cluster administrators can set and manage resource quotas on a per project basis, and how developers and cluster administrators can view them.

Resources managed by quotas

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

A pod is in a terminal state if status.phase in (Failed, Succeeded) is true.

Table 1. Compute resources managed by quota
Resource Name Description

cpu

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

memory

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

ephemeral-storage

The sum of local ephemeral storage requests across all pods in a non-terminal state cannot exceed this value. ephemeral-storage and requests.ephemeral-storage are the same value and can be used interchangeably. This resource is available only if you enabled the ephemeral storage technology preview. This feature is disabled by default.

requests.cpu

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

requests.memory

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

requests.ephemeral-storage

The sum of ephemeral storage requests across all pods in a non-terminal state cannot exceed this value. ephemeral-storage and requests.ephemeral-storage are the same value and can be used interchangeably. This resource is available only if you enabled the ephemeral storage technology preview. This feature is disabled by default.

limits.cpu

The sum of CPU limits across all pods in a non-terminal state cannot exceed this value.

limits.memory

The sum of memory limits across all pods in a non-terminal state cannot exceed this value.

limits.ephemeral-storage

The sum of ephemeral storage limits across all pods in a non-terminal state cannot exceed this value. This resource is available only if you enabled the ephemeral storage technology preview. This feature is disabled by default.

Table 2. Storage resources managed by quota
Resource Name Description

requests.storage

The sum of storage requests across all persistent volume claims in any state cannot exceed this value.

persistentvolumeclaims

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

<storage-class-name>.storageclass.storage.k8s.io/requests.storage

The sum of storage requests across all persistent volume claims in any state that have a matching storage class, cannot exceed this value.

<storage-class-name>.storageclass.storage.k8s.io/persistentvolumeclaims

The total number of persistent volume claims with a matching storage class that can exist in the project.

Table 3. 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.

replicationcontrollers

The total number of ReplicationControllers 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.

services.loadbalancers

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

services.nodeports

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

Quota scopes

Each quota can have an associated set of scopes. A quota only measures 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.

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 limiting 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

  • ephemeral-storage

  • requests.ephemeral-storage

  • limits.ephemeral-storage

Ephemeral storage requests and limits apply only if you enabled the ephemeral storage technology preview. This feature is disabled by default.

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 statistics are in the system.

Requests versus limits

When allocating compute resources, each container might specify a request and a limit value each for CPU, memory, and ephemeral storage. 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.

Sample resource quota definitions

core-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)
    services.loadbalancers: "2" (6)
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 ReplicationControllers 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.
6 The total number of services of type LoadBalancer that can exist in the project.
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 imagestreams that can exist in the project.
compute-resources.yaml
apiVersion: v1
kind: ResourceQuota
metadata:
  name: compute-resources
spec:
  hard:
    pods: "4" (1)
    requests.cpu: "1" (2)
    requests.memory: 1Gi (3)
    requests.ephemeral-storage: 2Gi (4)
    limits.cpu: "2" (5)
    limits.memory: 2Gi (6)
    limits.ephemeral-storage: 4Gi (7)
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 ephemeral storage requests cannot exceed 2Gi.
5 Across all pods in a non-terminal state, the sum of CPU limits cannot exceed 2 cores.
6 Across all pods in a non-terminal state, the sum of memory limits cannot exceed 2Gi.
7 Across all pods in a non-terminal state, the sum of ephemeral storage limits cannot exceed 4Gi.
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.
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)
    limits.ephemeral-storage: "4Gi" (4)
  scopes:
  - NotTerminating (5)
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 Across all pods in a non-terminal state, the sum of ephemeral storage limits cannot exceed this value.
5 Restricts the quota to only matching pods where spec.activeDeadlineSeconds is set to nil. Build pods will fall under NotTerminating unless the RestartNever policy is applied.
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)
    limits.ephemeral-storage: "1Gi" (4)
  scopes:
  - Terminating (5)
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 Across all pods in a non-terminal state, the sum of ephemeral storage limits cannot exceed this value.
5 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.
storage-consumption.yaml
apiVersion: v1
kind: ResourceQuota
metadata:
  name: storage-consumption
spec:
  hard:
    persistentvolumeclaims: "10" (1)
    requests.storage: "50Gi" (2)
    gold.storageclass.storage.k8s.io/requests.storage: "10Gi" (3)
    silver.storageclass.storage.k8s.io/requests.storage: "20Gi" (4)
    silver.storageclass.storage.k8s.io/persistentvolumeclaims: "5" (5)
    bronze.storageclass.storage.k8s.io/requests.storage: "0" (6)
    bronze.storageclass.storage.k8s.io/persistentvolumeclaims: "0" (7)
1 The total number of persistent volume claims in a project
2 Across all persistent volume claims in a project, the sum of storage requested cannot exceed this value.
3 Across all persistent volume claims in a project, the sum of storage requested in the gold storage class cannot exceed this value.
4 Across all persistent volume claims in a project, the sum of storage requested in the silver storage class cannot exceed this value.
5 Across all persistent volume claims in a project, the total number of claims in the silver storage class cannot exceed this value.
6 Across all persistent volume claims in a project, the sum of storage requested in the bronze storage class cannot exceed this value. When this is set to 0, it means bronze storage class cannot request storage.
7 Across all persistent volume claims in a project, the sum of storage requested in the bronze storage class cannot exceed this value. When this is set to 0, it means bronze storage class cannot create claims.

Creating a quota

You can create a quota to constrain resource usage in a given project.

Procedure
  1. Define the quota in a file.

  2. Use the file to create the quota and apply it to a project:

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

    For example:

    $ oc create -f core-object-counts.yaml -n demoproject

Creating object count quotas

You can create an object count quota for all OpenShift Container Platform standard namespaced resource types, such as BuildConfig, and DeploymentConfig. An object quota count places a defined quota on all standard namespaced resource types.

When using a resource quota, an object is charged against the quota if it exists in server storage. These types of quotas are useful to protect against exhaustion of storage resources.

Procedure

To configure an object count quota for a resource:

  1. Run the following command:

    $ oc create quota <name> \
        --hard=count/<resource>.<group>=<quota>,count/<resource>.<group>=<quota> (1)
    1 <resource> is the name of the resource, and <group> is the API group, if applicable. Use the oc api-resources command for a list of resources and their associated API groups.

    For example:

    $ oc create quota test \
        --hard=count/deployments.extensions=2,count/replicasets.extensions=4,count/pods=3,count/secrets=4
    resourcequota "test" created

    This example limits the listed resources to the hard limit in each project in the cluster.

  2. Verify that the quota was created:

    $ oc describe quota test
    Name:                         test
    Namespace:                    quota
    Resource                      Used  Hard
    --------                      ----  ----
    count/deployments.extensions  0     2
    count/pods                    0     3
    count/replicasets.extensions  0     4
    count/secrets                 0     4

Setting resource quota for extended resources

Overcommitment of resources is not allowed for extended resources, so you must specify requests and limits for the same extended resource in a quota. Currently, only quota items with the prefix requests. is allowed for extended resources. The following is an example scenario of how to set resource quota for the GPU resource nvidia.com/gpu.

Procedure
  1. Determine how many GPUs are available on a node in your cluster. For example:

    # oc describe node ip-172-31-27-209.us-west-2.compute.internal | egrep 'Capacity|Allocatable|gpu'
                        openshift.com/gpu-accelerator=true
    Capacity:
     nvidia.com/gpu:  2
    Allocatable:
     nvidia.com/gpu:  2
      nvidia.com/gpu  0           0

    In this example, 2 GPUs are available.

  2. Set a quota in the namespace nvidia. In this example, the quota is 1:

    # cat gpu-quota.yaml
    apiVersion: v1
    kind: ResourceQuota
    metadata:
      name: gpu-quota
      namespace: nvidia
    spec:
      hard:
        requests.nvidia.com/gpu: 1
  3. Create the quota:

    # oc create -f gpu-quota.yaml
    resourcequota/gpu-quota created
  4. Verify that the namespace has the correct quota set:

    # oc describe quota gpu-quota -n nvidia
    Name:                    gpu-quota
    Namespace:               nvidia
    Resource                 Used  Hard
    --------                 ----  ----
    requests.nvidia.com/gpu  0     1
  5. Run a pod that asks for a single GPU:

    # oc create -f gpu-pod.yaml
    apiVersion: v1
    kind: Pod
    metadata:
      generateName: gpu-pod-
      namespace: nvidia
    spec:
      restartPolicy: OnFailure
      containers:
      - name: rhel7-gpu-pod
        image: rhel7
        env:
          - name: NVIDIA_VISIBLE_DEVICES
            value: all
          - name: NVIDIA_DRIVER_CAPABILITIES
            value: "compute,utility"
          - name: NVIDIA_REQUIRE_CUDA
            value: "cuda>=5.0"
        command: ["sleep"]
        args: ["infinity"]
        resources:
          limits:
            nvidia.com/gpu: 1
  6. Verify that the pod is running:

    # oc get pods
    NAME              READY     STATUS      RESTARTS   AGE
    gpu-pod-s46h7     1/1       Running     0          1m
  7. Verify that the quota Used counter is correct:

    # oc describe quota gpu-quota -n nvidia
    Name:                    gpu-quota
    Namespace:               nvidia
    Resource                 Used  Hard
    --------                 ----  ----
    requests.nvidia.com/gpu  1     1
  8. Attempt to create a second GPU pod in the nvidia namespace. This is technically available on the node because it has 2 GPUs:

    # oc create -f gpu-pod.yaml
    Error from server (Forbidden): error when creating "gpu-pod.yaml": pods "gpu-pod-f7z2w" is forbidden: exceeded quota: gpu-quota, requested: requests.nvidia.com/gpu=1, used: requests.nvidia.com/gpu=1, limited: requests.nvidia.com/gpu=1

    This Forbidden error message is expected because you have a quota of 1 GPU and this pod tried to allocate a second GPU, which exceeds its quota.

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 Quota page.

You can also use the CLI to view quota details.

Procedure
  1. 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. 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, but before quota usage is restored, a user might encounter problems when attempting to reuse the resources. The synchronization time frame of resources is determined by the resource-quota-sync-period setting, which can be configured by a cluster administrator.

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.

Procedure

To configure the quota synchronization period:

  1. Edit the Kubernetes controller manager.

    $ oc edit kubecontrollermanager cluster
  2. Change the unsupportedconfigOverrides field to have the following settings, specifying the amount of time, in seconds, for the resource-quota-sync-period field:

      unsupportedConfigOverrides:
        extendedArguments:
          resource-quota-sync-period:
          - 60s