Configure Memory and CPU Quotas for a Namespace

This page shows how to set quotas for the total amount memory and CPU that can be used by all Containers running in a namespace. You specify quotas in a ResourceQuota object.

Before you begin

You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one by using minikube or you can use one of these Kubernetes playgrounds:

To check the version, enter kubectl version.

Each node in your cluster must have at least 1 GiB of memory.

Create a namespace

Create a namespace so that the resources you create in this exercise are isolated from the rest of your cluster.

  1. kubectl create namespace quota-mem-cpu-example

Create a ResourceQuota

Here is the configuration file for a ResourceQuota object:

admin/resource/quota-mem-cpu.yaml Configure Memory and CPU Quotas for a Namespace - 图1

  1. apiVersion: v1
  2. kind: ResourceQuota
  3. metadata:
  4.   name: mem-cpu-demo
  5. spec:
  6.   hard:
  7.     requests.cpu: "1"
  8.     requests.memory: 1Gi
  9.     limits.cpu: "2"
  10.     limits.memory: 2Gi

Create the ResourceQuota:

  1. kubectl apply -f https://k8s.io/examples/admin/resource/quota-mem-cpu.yaml --namespace=quota-mem-cpu-example

View detailed information about the ResourceQuota:

  1. kubectl get resourcequota mem-cpu-demo --namespace=quota-mem-cpu-example --output=yaml

The ResourceQuota places these requirements on the quota-mem-cpu-example namespace:

  • Every Container must have a memory request, memory limit, cpu request, and cpu limit.
  • The memory request total for all Containers must not exceed 1 GiB.
  • The memory limit total for all Containers must not exceed 2 GiB.
  • The CPU request total for all Containers must not exceed 1 cpu.
  • The CPU limit total for all Containers must not exceed 2 cpu.

Create a Pod

Here is the configuration file for a Pod:

admin/resource/quota-mem-cpu-pod.yaml Configure Memory and CPU Quotas for a Namespace - 图2

  1. apiVersion: v1
  2. kind: Pod
  3. metadata:
  4.   name: quota-mem-cpu-demo
  5. spec:
  6.   containers:
  7.   - name: quota-mem-cpu-demo-ctr
  8.     image: nginx
  9.     resources:
  10.       limits:
  11.         memory: "800Mi"
  12.         cpu: "800m"
  13.       requests:
  14.         memory: "600Mi"
  15.         cpu: "400m"

Create the Pod:

  1. kubectl apply -f https://k8s.io/examples/admin/resource/quota-mem-cpu-pod.yaml --namespace=quota-mem-cpu-example

Verify that the Pod’s Container is running:

  1. kubectl get pod quota-mem-cpu-demo --namespace=quota-mem-cpu-example

Once again, view detailed information about the ResourceQuota:

  1. kubectl get resourcequota mem-cpu-demo --namespace=quota-mem-cpu-example --output=yaml

The output shows the quota along with how much of the quota has been used. You can see that the memory and CPU requests and limits for your Pod do not exceed the quota.

  1. status:
  2.   hard:
  3.     limits.cpu: "2"
  4.     limits.memory: 2Gi
  5.     requests.cpu: "1"
  6.     requests.memory: 1Gi
  7.   used:
  8.     limits.cpu: 800m
  9.     limits.memory: 800Mi
  10.     requests.cpu: 400m
  11.     requests.memory: 600Mi

Attempt to create a second Pod

Here is the configuration file for a second Pod:

admin/resource/quota-mem-cpu-pod-2.yaml Configure Memory and CPU Quotas for a Namespace - 图3

  1. apiVersion: v1
  2. kind: Pod
  3. metadata:
  4.   name: quota-mem-cpu-demo-2
  5. spec:
  6.   containers:
  7.   - name: quota-mem-cpu-demo-2-ctr
  8.     image: redis
  9.     resources:
  10.       limits:
  11.         memory: "1Gi"
  12.         cpu: "800m"
  13.       requests:
  14.         memory: "700Mi"
  15.         cpu: "400m"

In the configuration file, you can see that the Pod has a memory request of 700 MiB. Notice that the sum of the used memory request and this new memory request exceeds the memory request quota. 600 MiB + 700 MiB > 1 GiB.

Attempt to create the Pod:

  1. kubectl apply -f https://k8s.io/examples/admin/resource/quota-mem-cpu-pod-2.yaml --namespace=quota-mem-cpu-example

The second Pod does not get created. The output shows that creating the second Pod would cause the memory request total to exceed the memory request quota.

  1. Error from server (Forbidden): error when creating "examples/admin/resource/quota-mem-cpu-pod-2.yaml":
  2. pods "quota-mem-cpu-demo-2" is forbidden: exceeded quota: mem-cpu-demo,
  3. requested: requests.memory=700Mi,used: requests.memory=600Mi, limited: requests.memory=1Gi

Discussion

As you have seen in this exercise, you can use a ResourceQuota to restrict the memory request total for all Containers running in a namespace. You can also restrict the totals for memory limit, cpu request, and cpu limit.

If you want to restrict individual Containers, instead of totals for all Containers, use a LimitRange.

Clean up

Delete your namespace:

  1. kubectl delete namespace quota-mem-cpu-example

What’s next

For cluster administrators

For app developers