Tasks

Step-by-step instructions for performing operations with Kubernetes.

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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:

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.

kubectl create namespace quota-mem-cpu-example

Create a ResourceQuota

Here is the configuration file for a ResourceQuota object:

quota-mem-cpu.yaml
apiVersion: v1
kind: ResourceQuota
metadata:
  name: mem-cpu-demo
spec:
  hard:
    requests.cpu: "1"
    requests.memory: 1Gi
    limits.cpu: "2"
    limits.memory: 2Gi

Create the ResourceQuota:

kubectl create -f https://k8s.io/docs/tasks/administer-cluster/quota-mem-cpu.yaml --namespace=quota-mem-cpu-example

View detailed information about the ResourceQuota:

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:

Create a Pod

Here is the configuration file for a Pod:

quota-mem-cpu-pod.yaml
apiVersion: v1
kind: Pod
metadata:
  name: quota-mem-cpu-demo
spec:
  containers:
  - name: quota-mem-cpu-demo-ctr
    image: nginx
    resources:
      limits:
        memory: "800Mi"
        cpu: "800m" 
      requests:
        memory: "600Mi"
        cpu: "400m"

Create the Pod:

kubectl create -f https://k8s.io/docs/tasks/administer-cluster/quota-mem-cpu-pod.yaml --namespace=quota-mem-cpu-example

Verify that the Pod’s Container is running:

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

Once again, view detailed information about the ResourceQuota:

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.

status:
  hard:
    limits.cpu: "2"
    limits.memory: 2Gi
    requests.cpu: "1"
    requests.memory: 1Gi
  used:
    limits.cpu: 800m
    limits.memory: 800Mi
    requests.cpu: 400m
    requests.memory: 600Mi

Attempt to create a second Pod

Here is the configuration file for a second Pod:

quota-mem-cpu-pod-2.yaml
apiVersion: v1
kind: Pod
metadata:
  name: quota-mem-cpu-demo-2
spec:
  containers:
  - name: quota-mem-cpu-demo-2-ctr
    image: redis
    resources:
      limits:
        memory: "1Gi"
        cpu: "800m"      
      requests:
        memory: "700Mi"
        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:

kubectl create -f https://k8s.io/docs/tasks/administer-cluster/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.

Error from server (Forbidden): error when creating "docs/tasks/administer-cluster/quota-mem-cpu-pod-2.yaml":
pods "quota-mem-cpu-demo-2" is forbidden: exceeded quota: mem-cpu-demo,
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:

kubectl delete namespace quota-mem-cpu-example

What’s next

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