KEDA is a Kubernetes-based Event Driven Autoscaler. With KEDA, you can drive the scaling of any container in Kubernetes based on the number of events needing to be processed.
The following demo is based on the examples here
Install KEDA
Follow setups in KEDA docs
I used Helm 3 method
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| kubectl create namespace keda
helm install keda kedacore/keda --namespace keda
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Install Prometheus
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| apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRole
metadata:
name: prometheus
rules:
- apiGroups: [""]
resources:
- services
verbs: ["get", "list", "watch"]
- nonResourceURLs: ["/metrics"]
verbs: ["get"]
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: default
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
name: prometheus
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: prometheus
subjects:
- kind: ServiceAccount
name: default
namespace: default
---
apiVersion: v1
kind: ConfigMap
metadata:
name: prom-conf
labels:
name: prom-conf
data:
prometheus.yml: |-
global:
scrape_interval: 5s
evaluation_interval: 5s
scrape_configs:
- job_name: 'go-prom-job'
kubernetes_sd_configs:
- role: service
relabel_configs:
- source_labels: [__meta_kubernetes_service_label_run]
regex: go-prom-app-service
action: keep
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: prometheus-deployment
spec:
replicas: 1
selector:
matchLabels:
app: prometheus-server
template:
metadata:
labels:
app: prometheus-server
spec:
containers:
- name: prometheus
image: prom/prometheus
args:
- "--config.file=/etc/prometheus/prometheus.yml"
- "--storage.tsdb.path=/prometheus/"
ports:
- containerPort: 9090
volumeMounts:
- name: prometheus-config-volume
mountPath: /etc/prometheus/
- name: prometheus-storage-volume
mountPath: /prometheus/
volumes:
- name: prometheus-config-volume
configMap:
defaultMode: 420
name: prom-conf
- name: prometheus-storage-volume
emptyDir: {}
---
apiVersion: v1
kind: Service
metadata:
name: prometheus-service
spec:
ports:
- port: 9090
protocol: TCP
selector:
app: prometheus-server
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Check prometheus from UI
kubectl port-forward service/prometheus-service 9090- open
localhost:9090 in a browser
Install redis for the demo app
helm install redis-server --set cluster.enabled=false --set usePassword=false stable/redis
Deploy demo app
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| apiVersion: apps/v1
kind: Deployment
metadata:
name: go-prom-app
spec:
replicas: 1
selector:
matchLabels:
app: go-prom-app
template:
metadata:
labels:
app: go-prom-app
spec:
containers:
- name: go-prom-app
image: abhirockzz/go-prom-app
env:
- name: REDIS_HOST
value: redis-server-master.default.svc.cluster.local
- name: REDIS_PORT
value: "6379"
imagePullPolicy: Always
ports:
- containerPort: 8080
---
apiVersion: v1
kind: Service
metadata:
name: go-prom-app-service
labels:
run: go-prom-app-service
spec:
ports:
- port: 8080
protocol: TCP
selector:
app: go-prom-app
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Make sure you can see the demo app in the prometheus targets page http://localhost:9090/targets
Deploy KEDA ScaledObject resource
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| apiVersion: keda.k8s.io/v1alpha1
kind: ScaledObject
metadata:
name: prometheus-scaledobject
namespace: default
labels:
deploymentName: go-prom-app
spec:
scaleTargetRef:
deploymentName: go-prom-app
pollingInterval: 15 # Optional. Default: 30 seconds
cooldownPeriod: 30 # Optional. Default: 300 seconds
minReplicaCount: 1 # Optional. Default: 0
maxReplicaCount: 10 # Optional. Default: 100
triggers:
- type: prometheus
metadata:
# Required
serverAddress: http://prometheus-service.default.svc.cluster.local:9090
metricName: access_frequency
threshold: '3'
query: sum(rate(http_requests[2m]))
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Testing KEDA
Make the demo app accessible locally
kubectl port-forward service/go-prom-app-service 8080
View current pods
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| # kubectl get pod
NAME READY STATUS RESTARTS AGE
go-prom-app-5547b97ccd-l5p8v 1/1 Running 0 6m
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watch pod changes:
kubectl get pods -l=app=go-prom-app -w
Start load testing
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| echo "GET http://localhost:8080/test" | vegeta attack -duration=100s | tee results.bin | vegeta report
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I am using vegeta for the loading here.
You will see number of pods increases.
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| # kubectl get pods -l=app=go-prom-app -w
NAME READY STATUS RESTARTS AGE
go-prom-app-5547b97ccd-l5p8v 1/1 Running 0 7h6m
go-prom-app-5547b97ccd-l8nsz 0/1 Pending 0 0s
go-prom-app-5547b97ccd-l8nsz 0/1 Pending 0 0s
go-prom-app-5547b97ccd-l8nsz 0/1 ContainerCreating 0 0s
go-prom-app-5547b97ccd-l8nsz 1/1 Running 0 4s
go-prom-app-5547b97ccd-7c64n 0/1 Pending 0 0s
go-prom-app-5547b97ccd-7c64n 0/1 Pending 0 0s
go-prom-app-5547b97ccd-tj8gw 0/1 Pending 0 0s
go-prom-app-5547b97ccd-tj8gw 0/1 Pending 0 0s
go-prom-app-5547b97ccd-7c64n 0/1 ContainerCreating 0 0s
go-prom-app-5547b97ccd-tj8gw 0/1 ContainerCreating 0 0s
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