You can manually scale replicas (pods) to test how your application responds to a change in available resources and state. Manually scaling resources also lets you define a set amount of resources to use to maintain a fixed cost. To manually scale, you define the replica count. The Kubernetes API then schedules creating additional pods based on that replica count.
Make sure that the load script is still running. If not run it again
# Generate some load to guinea-pig application
kubectl run -i --tty load-generator --rm --image=busybox --restart=Never -- /bin/sh -c "while sleep 0.01; do wget -q -O- http://guinea-pig-service/api/highcpu; done"Now, let's scale guinea-pig application to 3 instances and see how it will affect the performance.
# Scaling guinea-pig to 3 instances
kubectl scale deployment/guinea-pig --replicas=3
# Check that new pods are up and running
kubectl get po -w
NAME READY STATUS RESTARTS AGE
guinea-pig-6c994669b7-4p4b4 1/1 Running 0 7s
guinea-pig-6c994669b7-95n75 1/1 Running 0 7s
guinea-pig-6c994669b7-xnvnr 1/1 Running 0 36m
load-generator 1/1 Running 0 15mWait about 1-2 mins and refresh your dashboard. You should see that CPU usage dropped and our application is performing within acceptable CPU range (below 70%).
# Scaling guinea-pig to 3 instances
kubectl scale deployment/guinea-pig --replicas=1
# Check that we are back to one pod
kubectl get po -w
NAME READY STATUS RESTARTS AGE
guinea-pig-6c994669b7-xnvnr 1/1 Running 0 59m
load-generator 1/1 Running 0 38m