Day 17/40
Kubernetes Autoscaling | HPA Vs VPA
Video Link
@piyushsachdeva
Git Repository
My Git Repo
In this section, we're going to explain Auto Scaling, HPA and VPA.
Scaling is changing your workloads to meet the demand and it can be manually or automatically.
Three common solutions for scaling applications in Kubernetes environments are:
- Horizontal Pod Autoscaler (HPA): Automatically adds or removes for example pod replicas.
- Vertical Pod Autoscaler (VPA): Automatically adds or adjusts resources for example CPU and memory reservations for your pods.
- Cluster Autoscaler: Automatically adds or removes nodes in a cluster based on all pods’ requested resources.
(Photo from the video)
(Photo from the video)
There are another types of autoscaling for instance:
- Event based autoscaling (KEDA)
- Cron/Schedule based autoscaling
Demo
For doing some hands-on demo, we need the metrics-server pod is running.
root@localhost:~# kubectl get pods -n kube-system
NAME READY STATUS RESTARTS AGE
coredns-7db6d8ff4d-bftnd 1/1 Running 1 (13d ago) 14d
coredns-7db6d8ff4d-zs54d 1/1 Running 1 (13d ago) 14d
etcd-lucky-luke-control-plane 1/1 Running 1 (13d ago) 14d
kindnet-fbwgj 1/1 Running 1 (13d ago) 14d
kindnet-hxb7v 1/1 Running 1 (13d ago) 14d
kindnet-kh5s6 1/1 Running 1 (13d ago) 14d
kube-apiserver-lucky-luke-control-plane 1/1 Running 1 (13d ago) 14d
kube-controller-manager-lucky-luke-control-plane 1/1 Running 1 (13d ago) 14d
kube-proxy-42h2f 1/1 Running 1 (13d ago) 14d
kube-proxy-dhzrs 1/1 Running 1 (13d ago) 14d
kube-proxy-rlzwk 1/1 Running 1 (13d ago) 14d
kube-scheduler-lucky-luke-control-plane 1/1 Running 1 (13d ago) 14d
metrics-server-55677cdb4c-t5wrw 1/1 Running 0 108s
- The deployment yaml file:
apiVersion: apps/v1
kind: Deployment
metadata:
name: php-apache
spec:
selector:
matchLabels:
run: php-apache
template:
metadata:
labels:
run: php-apache
spec:
containers:
- name: php-apache
image: registry.k8s.io/hpa-example
ports:
- containerPort: 80
resources:
limits:
cpu: 500m
requests:
cpu: 200m
---
apiVersion: v1
kind: Service
metadata:
name: php-apache
labels:
run: php-apache
spec:
ports:
- port: 80
selector:
run: php-apache
It implements 2 workloads in one yaml file, one for deployment and one for service with 3 - between them.
Let's run them
root@localhost:~# kubectl apply -f day17-deploy.yaml
deployment.apps/php-apache created
service/php-apache created
root@localhost:~# kubectl get po,deploy,svc
NAME READY STATUS RESTARTS AGE
pod/php-apache-678865dd57-rlgqw 1/1 Running 0 67s
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/php-apache 1/1 1 1 67s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 14d
service/php-apache ClusterIP 10.96.250.6 <none> 80/TCP 67s
We define 50% threshold for cpu usage for the deployment and minimum and maximum replica for it.
root@localhost:~# kubectl autoscale deploy php-apache --cpu-percent=50 --min=1 --max=10
horizontalpodautoscaler.autoscaling/php-apache autoscaled
root@localhost:~# kubect get hpa
kubect: command not found
root@localhost:~# kubectl get hpa
NAME REFERENCE TARGETS MINPODS MAXPODS REPLICAS AGE
php-apache Deployment/php-apache cpu: 0%/50% 1 10 1 17s
Now, we generate some loads on the deployment and see what will be happened.
root@localhost:~# kubectl run -i --tty load-generator --rm --image=busybox:1.28 --restart=Never -- /bin/sh -c "while sleep 0.01; do wget -q -O- http://php-apache; done"
OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!
root@localhost:~# kubectl get po,deploy,svc,hpa
NAME READY STATUS RESTARTS AGE
pod/load-generator 1/1 Running 0 9s
pod/php-apache-678865dd57-rlgqw 1/1 Running 0 13m
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/php-apache 1/1 1 1 13m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 14d
service/php-apache ClusterIP 10.96.250.6 <none> 80/TCP 13m
NAME REFERENCE TARGETS MINPODS MAXPODS REPLICAS AGE
horizontalpodautoscaler.autoscaling/php-apache Deployment/php-apache cpu: 0%/50% 1 10 1 6m45s
root@localhost:~# kubectl get po,deploy,svc,hpa
NAME READY STATUS RESTARTS AGE
pod/load-generator 1/1 Running 0 30s
pod/php-apache-678865dd57-g4gl6 1/1 Running 0 6s
pod/php-apache-678865dd57-rlgqw 1/1 Running 0 13m
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/php-apache 2/2 2 2 13m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 14d
service/php-apache ClusterIP 10.96.250.6 <none> 80/TCP 13m
NAME REFERENCE TARGETS MINPODS MAXPODS REPLICAS AGE
horizontalpodautoscaler.autoscaling/php-apache Deployment/php-apache cpu: 61%/50% 1 10 1 7m6s
root@localhost:~# kubectl get po,deploy,svc,hpa
NAME READY STATUS RESTARTS AGE
pod/load-generator 1/1 Running 0 99s
pod/php-apache-678865dd57-g4gl6 1/1 Running 0 75s
pod/php-apache-678865dd57-gfjpb 1/1 Running 0 15s
pod/php-apache-678865dd57-gh5fl 1/1 Running 0 60s
pod/php-apache-678865dd57-hkn4b 1/1 Running 0 60s
pod/php-apache-678865dd57-k4g55 1/1 Running 0 45s
pod/php-apache-678865dd57-rlgqw 1/1 Running 0 15m
pod/php-apache-678865dd57-td5ht 1/1 Running 0 45s
pod/php-apache-678865dd57-w69s2 1/1 Running 0 15s
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/php-apache 8/8 8 8 15m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 14d
service/php-apache ClusterIP 10.96.250.6 <none> 80/TCP 15m
NAME REFERENCE TARGETS MINPODS MAXPODS REPLICAS AGE
horizontalpodautoscaler.autoscaling/php-apache Deployment/php-apache cpu: 59%/50% 1 10 6 8m15s
And when we stop the loads, the replicas start to decreasing
OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!OK!^Cpod "load-generator" deleted
pod default/load-generator terminated (Error)
root@localhost:~# kubectl get po,deploy,svc,hpa
NAME READY STATUS RESTARTS AGE
pod/php-apache-678865dd57-rlgqw 1/1 Running 0 21m
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/php-apache 1/1 1 1 21m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 14d
service/php-apache ClusterIP 10.96.250.6 <none> 80/TCP 21m
NAME REFERENCE TARGETS MINPODS MAXPODS REPLICAS AGE
horizontalpodautoscaler.autoscaling/php-apache Deployment/php-apache cpu: 0%/50% 1 10 2 14m
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