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| title | content_template | weight |
|---|---|---|
| Configure Quality of Service for Pods | templates/task | 30 |
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This page shows how to configure Pods so that they will be assigned particular Quality of Service (QoS) classes. Kubernetes uses QoS classes to make decisions about scheduling and evicting Pods.
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QoS classes
When Kubernetes creates a Pod it assigns one of these QoS classes to the Pod:
- Guaranteed
- Burstable
- BestEffort
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 qos-example
Create a Pod that gets assigned a QoS class of Guaranteed
For a Pod to be given a QoS class of Guaranteed:
- Every Container in the Pod must have a memory limit and a memory request, and they must be the same.
- Every Container in the Pod must have a CPU limit and a CPU request, and they must be the same.
Here is the configuration file for a Pod that has one Container. The Container has a memory limit and a memory request, both equal to 200 MiB. The Container has a CPU limit and a CPU request, both equal to 700 milliCPU:
{{< codenew file="pods/qos/qos-pod.yaml" >}}
Create the Pod:
kubectl create -f https://k8s.io/examples/pods/qos/qos-pod.yaml --namespace=qos-example
View detailed information about the Pod:
kubectl get pod qos-demo --namespace=qos-example --output=yaml
The output shows that Kubernetes gave the Pod a QoS class of Guaranteed. The output also verifies that the Pod Container has a memory request that matches its memory limit, and it has a CPU request that matches its CPU limit.
spec:
containers:
...
resources:
limits:
cpu: 700m
memory: 200Mi
requests:
cpu: 700m
memory: 200Mi
...
qosClass: Guaranteed
{{< note >}} Note: If a Container specifies its own memory limit, but does not specify a memory request, Kubernetes automatically assigns a memory request that matches the limit. Similarly, if a Container specifies its own CPU limit, but does not specify a CPU request, Kubernetes automatically assigns a CPU request that matches the limit. {{< /note >}}
Delete your Pod:
kubectl delete pod qos-demo --namespace=qos-example
Create a Pod that gets assigned a QoS class of Burstable
A Pod is given a QoS class of Burstable if:
- The Pod does not meet the criteria for QoS class Guaranteed.
- At least one Container in the Pod has a memory or CPU request.
Here is the configuration file for a Pod that has one Container. The Container has a memory limit of 200 MiB and a memory request of 100 MiB.
{{< codenew file="pods/qos/qos-pod-2.yaml" >}}
Create the Pod:
kubectl create -f https://k8s.io/examples/pods/qos/qos-pod-2.yaml --namespace=qos-example
View detailed information about the Pod:
kubectl get pod qos-demo-2 --namespace=qos-example --output=yaml
The output shows that Kubernetes gave the Pod a QoS class of Burstable.
spec:
containers:
- image: nginx
imagePullPolicy: Always
name: qos-demo-2-ctr
resources:
limits:
memory: 200Mi
requests:
memory: 100Mi
...
qosClass: Burstable
Delete your Pod:
kubectl delete pod qos-demo-2 --namespace=qos-example
Create a Pod that gets assigned a QoS class of BestEffort
For a Pod to be given a QoS class of BestEffort, the Containers in the Pod must not have any memory or CPU limits or requests.
Here is the configuration file for a Pod that has one Container. The Container has no memory or CPU limits or requests:
{{< codenew file="pods/qos/qos-pod-3.yaml" >}}
Create the Pod:
kubectl create -f https://k8s.io/examples/pods/qos/qos-pod-3.yaml --namespace=qos-example
View detailed information about the Pod:
kubectl get pod qos-demo-3 --namespace=qos-example --output=yaml
The output shows that Kubernetes gave the Pod a QoS class of BestEffort.
spec:
containers:
...
resources: {}
...
qosClass: BestEffort
Delete your Pod:
kubectl delete pod qos-demo-3 --namespace=qos-example
Create a Pod that has two Containers
Here is the configuration file for a Pod that has two Containers. One container specifies a memory request of 200 MiB. The other Container does not specify any requests or limits.
{{< codenew file="pods/qos/qos-pod-4.yaml" >}}
Notice that this Pod meets the criteria for QoS class Burstable. That is, it does not meet the criteria for QoS class Guaranteed, and one of its Containers has a memory request.
Create the Pod:
kubectl create -f https://k8s.io/examples/pods/qos/qos-pod-4.yaml --namespace=qos-example
View detailed information about the Pod:
kubectl get pod qos-demo-4 --namespace=qos-example --output=yaml
The output shows that Kubernetes gave the Pod a QoS class of Burstable:
spec:
containers:
...
name: qos-demo-4-ctr-1
resources:
requests:
memory: 200Mi
...
name: qos-demo-4-ctr-2
resources: {}
...
qosClass: Burstable
Delete your Pod:
kubectl delete pod qos-demo-4 --namespace=qos-example
Clean up
Delete your namespace:
kubectl delete namespace qos-example
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