There are two ways to set a Resource QoS: pod configuration or namespace configuration. If you set a Resource QoS to the Namespace, it will apply to all pods that belong to the same Namespace. If you set a Resource QoS to a pod, it will apply to the pod only. In addition, if you set it to both namespace and pod, it takes a value from the namespace configuration first, and then overwrite it with the pod configuration. Thus, we will set up two Namespaces, one which has a Resource QoS, and one that does not, to see how different they are:

1. Create two namespaces by using the kubectl command as follows:

$ kubectl create namespace chap8-no-qos
namespace "chap8-no-qos" created

$ kubectl create namespace chap8-qos
namespace "chap8-qos" created

2. Prepare a YAML file that sets spec.limits.defaultRequest.cpu: 0.1 as follows:

$ cat resource-request-cpu.yml
apiVersion: v1
kind: LimitRange
metadata:
  name: resource-request-cpu
spec:
  limits:
  - defaultRequest:
      cpu: 0.1
    type: Container

3. Do this by typing the kubectl command so that it applies to the chap8-qos namespace only:

$ kubectl create -f resource-request-cpu.yml --namespace=chap8-qos
limitrange "resource-request-cpu" created

4. Check the resource limit on both chap8-qos and chap8-no-qos with the kubectl command:

//chap8-no-qos doesn't have any resource limits value
$ kubectl describe namespaces chap8-no-qos
Name:         chap8-no-qos
Labels:       <none>
Annotations:  <none>
Status:       Active
No resource quota.
No resource limits.


//chap8-qos namespace has a resource limits value
$ kubectl describe namespaces chap8-qos
Name:         chap8-qos
Labels:       <none>
Annotations:  <none>
Status:       Active
No resource quota.
Resource Limits
 Type       Resource  Min  Max  Default Request  Default Limit  Max Limit/Request Ratio
 ----       --------  ---  ---  ---------------  -------------  -----------------------
 Container  cpu       -    -    100m             -              -