Thursday, May 17, 2018

kubernetes - Resource quota

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

Create a resource quota config file as
apiVersion: v1
kind: ResourceQuota
metadata:
  name: pod-demo
spec:
  hard:
    pods: "2"

In our resource quota file we have limited our number of pod creation to 2. 

Create the resource quota as,
[root@manja17-I13330 kubenetes-config]# kubectl create -f basic-resourcequota.yml --namespace=sample-testing
resourcequota "pod-demo" created

Once created , add the resource quota to a namespace as,
[root@manja17-I13330 kubenetes-config]# kubectl get resourcequota --namespace=sample-testing
NAME       AGE
pod-demo   55s

When we get the pods, we see we already have 2 pods running in this namespace,

[root@manja17-I13330 kubenetes-config]# kubectl get pods --namespace=sample-testing
NAME                                    READY STATUS RESTARTS AGE
test-service-deploy-85c8787b6f-sfprn   1/1 Running 0 57s
test-service-deploy-85c8787b6f-wvnfc  1/1 Running 0 14s

Now lets try to create a new pod and see how it goes
[root@manja17-I13330 kubenetes-config]# cat basic-single-container-pod.yml
apiVersion: v1
kind: Pod
metadata:
 name: testing-service
spec:
 containers:
   - name: test-ser
     image: docker.io/jagadesh1982/testing-service
     ports:
     - containerPort: 9876
     resources:
       limits:
         memory: "64Mi"
         cpu: "500m"

[root@manja17-I13330 kubenetes-config]# kubectl create -f  basic-single-container-pod.yml --namespace=sample-testing

Error from server (Forbidden): error when creating "basic-single-container-pod.yml": pods "testing-service" is forbidden: exceeded quota: pod-demo, requested: pods=1, used: pods=2, limited: pods=2

Now when i run the pod creation it gives me an error saying that the resource quota limit for pod is reached and cannot create any more.

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