loadGen

React app to view metrics and to start/stop load testing (displays only readyReplicas for now. Similarly other metrics like cpu, memory utilization and more can be added)

3 deployments

• React app served on nginx
• node server to generate load
• node server subjected to load

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Requires a kubernetes environment up and running with additional default addons:

• metrics-server
• ingress

Consider these as you rollout HPA(step 8):

• The default HPA check interval is 30 seconds. This can be configured through the --horizontal-pod-autoscaler-sync-period flag of the controller manager

• HPA waits for 3 minutes after the last scale-up events to allow metrics to stabilize. This can also be configured through -- horizontal-pod-autoscaler-upscale-delay flag

• HPA waits for 5 minutes from the last scale-down event to avoid autoscaler thrashing. Configurable through — horizontal-pod-autoscaler-downscale-delay flag

for minikube

$ minikube start — extra-config=controller-manager.horizontal-pod-autoscaler-upscale-delay=1m — extra-config=controller-manager.horizontal-pod-autoscaler-downscale-delay=1m — extra-config=controller-manager.horizontal-pod-autoscaler-sync-period=10s — extra-config=controller-manager.horizontal-pod-autoscaler-downscale-stabilization=1m

Build images

$ docker build -t <name>:<tag> ./frontend/
$ docker build -t <name>:<tag> ./backend/loadgen/
$ docker build -t <name>:<tag> ./backend/loadnode/

change image name and tag in *.deployment.yaml files accordingly

kubectl away

ServiceAccount, Role and RoleBinding

1. create a serice account named testsa in default namespace

$ kubectl create sa testsa

2. create a role that allows pods to access resource: deployments with verbs: get, watch, list (just enough permissions to get no. of ready replicas)

$ kubectl create -f testsa-role.yaml

3. Bind this role to the testsa service account (pods with testsa service account now will have permissions to access resource: deployments with verbs: get, watch, list)

$ kubectl create -f testsa-rolebinding.yaml

volume mount

create /home/flag/flag.txt file (used as hostPath volume mount). It is written with boolean value by node-app-containers. Since request to stop load may not be directed to the same pod that served to start load as there are multiple replicas of the same pod, value is read from fla.txt and runs/breaks loop to generate/stop load.

Backend

4. create loadnode-deployment and service (server subjected to load)

$ kubectl create -f loadnode-deployment.yaml
$ kubectl create -f loadnode-service.yaml

5. create node-app-deployment and service (server that causes load)

$ kubectl create -f node-app-deployment.yaml
$ kubectl create -f node-app-service.yaml

Frontend

6. create react-service1-deployment and service (frontend)

$ kubectl create -f react-service1-deployment.yaml
$ kubectl create -f react-service1-service.yaml

7. create ingress to reach your frontend application.

$ kubectl create -f test-ingress.yaml

To check IP of ingress.

$ kubectl describe ingress react-ingress

Horizontal pod autoscaler

8. hpa maintains average cpu utilization of 4% across all pods and scales up/down accordingly

$ kubectl autoscale deployment loadnode-app-deployment --cpu-percent=4 --min=1 --max=4 

Test

• Access Ingress IP from browser and react application should be displayed.
• press on "getReplicas". Should show "1" as there is no load yet.
• press "genLoad" and wait for a minute
• Meanwhile open and exec kubectl get hpa loadnode-app-deployment -w to monitor the avg CPU utilization.
• Once average crosses 4%, pods are upscaled to max of 4.
• press "stopLoad" and wait. You should see falling cpu utilization and reducing number of replicas