Create a Kubernetes Metrics Server
1. To clone the GitHub repository of metrics-server, run the following command:
git clone https://github.com/kubernetes-incubator/metrics-server.git
cd metrics-server/
2. To install Metrics Server from the root of the Metrics Server directory, run the following command:
kubectl create -f deploy/1.8+/
3. To confirm that Metrics Server is running, run the following command:
kubectl get pods -n kube-system
The output should look similar to the following:
$ kubectl get pods -n kube-system | grep metrics-server
metrics-server-85cc795fbf-79d72 1/1 Running 0 22s
Create a php-apache deployment and a service
1. To create a php-apache deployment, run the following command:
kubectl create deployment php-apache --image=k8s.gcr.io/hpa-example
2. To set the CPU requests, run the following command:
kubectl patch deployment php-apache
-p='{"spec":{"template":{"spec":{"containers":[{"name":"hpa-example","resources":{"requests":{"cpu":"200m"}}}]}}}}'
Important: If you don’t set the value for cpu correctly, then the CPU utilization metric for the pod won’t be defined and the HPA can’t scale.
3. To expose the deployment as a service, run the following command:
kubectl create service clusterip php-apache --tcp=80
4. To create an HPA, run the following command:
kubectl autoscale deployment php-apache --cpu-percent=50 --min=1 --max=10
5. To confirm that the HPA was created, run the following command.
kubectl get hpa
6. To create apod to connect to the deployment that you created earlier, run the following command:
kubectl run --generator=run-pod/v1 -i --tty load-generator --image=busybox /bin/sh
7. To test a load on the pod in the namespace that you used in step 1, run the following script:
while true; do wget -q -O- http://php-apache; done
Note: To exit the while loop and the tty session of the load generator pod, use CTRL + Cto cancel the loop, and then use CTRL + D to exit the session.
8. To see how the HPA scales the pod based on CPU utilization metrics, run the following command (preferably from another terminal window):
kubectl get hpa -w
TheMetrics Server is now up and running, and you can use it to get resource-based metrics.
9. To clean up the resources used for testing the HPA, run the following commands:
kubectl delete hpa,service,deployment php-apache
kubectl delete pod load-generator
VirtuallyLG 