KEDA example

This repository consists of everything you need to setup simple Kubernetes cluster and demonstrate usage of KEDA redis and mysql scalers. For more samples check https://github.com/kedacore/samples

The included helper provides an easy way to perform both 0 -> n and n -> 0 scalings.

Create cluster

The deployment consists of 4 components:

MySQL instance
Redis instance
Dummy pod that will be scaled up and down
App service that provides some helper methods

kubectl apply -f deployment/

Install KEDA

Follow the official KEDA guide https://keda.sh/deploy/

Observe

To observe how everything works you can watch two things:

number of pods and their state: watch -n2 "kubectl get pods"
HPA stats: watch -n2 "kubectl get hpa"

Redis example

To scale the dummy deployment using Redis scaler first we have to deploy the ScaledObjects:

kubectl apply -f keda/redis-hpa.yaml

this should result in creation of a new ScaledObjects and new HPA

# kubectl get scaledobjects
NAME                 DEPLOYMENT   TRIGGERS   AGE
redis-scaledobject   dummy        redis      5s

# kubectl get hpa
NAME             REFERENCE          TARGETS              MINPODS   MAXPODS   REPLICAS   AGE
keda-hpa-dummy   Deployment/dummy   <unknown>/10 (avg)   1         4         0          45s

To scale up we have to populate the Redis queue. To do this we can use the helper app:

kubectl exec $(kubectl get pods | grep "server" | cut -f 1 -d " ") -- keda-talk redis publish

and to scale down:

kubectl exec $(kubectl get pods | grep "server" | cut -f 1 -d " ") -- keda-talk redis drain

MySQL example

To scale the dummy deployment using MySQL scaler first we have to deploy the ScaledObjects:

kubectl apply -f keda/mysql-hpa.yaml

this should result again in creation of ScaleObject and an HPA:

# kubectl get scaledobjects
NAME                 DEPLOYMENT   TRIGGERS   AGE
mysql-scaledobject   dummy        redis      5s

# kubectl get hpa
NAME             REFERENCE          TARGETS              MINPODS   MAXPODS   REPLICAS   AGE
keda-hpa-dummy   Deployment/dummy   <unknown>/10 (avg)   1         4         0          45s

To scale up we have to insert some values to MySQL database. To do this we can use the helper app:

kubectl exec $(kubectl get pods | grep "server" | cut -f 1 -d " ") -- keda-talk mysql insert