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autoscaling/readme.md

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+# Kubernetes Autoscaling Guide
+
+## Cluster Autoscaling
+
+Cluster autoscaler allows us to scale cluster nodes when they become full <br/>
+I would recommend to learn about scaling your cluster nodes before scaling pods. <br/>
+
+## Horizontal Pod Autoscaling
+
+HPA allows us to scale pods when their resource utilisation goes over a threshold <br/>
+
+## Requirements
+
+### A Cluster 
+
+* For both autoscaling guides, we'll need a cluster. <br/>
+* For `Cluster Autoscaler` You need a cloud based cluster that supports the cluster autoscaler <br/>
+* For `HPA` We'll use [kind](http://kind.sigs.k8s.io/)
+
+### Cluster Autoscaling - Creating an AKS Cluster
+
+```
+# azure example
+
+NAME=aks-getting-started
+RESOURCEGROUP=aks-getting-started
+SERVICE_PRINCIPAL=
+SERVICE_PRINCIPAL_SECRET=
+
+az aks create -n $NAME \
+--resource-group $RESOURCEGROUP \
+--location australiaeast \
+--kubernetes-version 1.16.10 \
+--nodepool-name default \
+--node-count 1 \
+--node-vm-size Standard_F4s_v2  \
+--node-osdisk-size 250 \
+--service-principal $SERVICE_PRINCIPAL \
+--client-secret $SERVICE_PRINCIPAL_SECRET \
+--output none \
+--enable-cluster-autoscaler \
+--min-count 1 \
+--max-count 5
+```
+
+### Horizontal Pod Autocaling - Creating a Kind Cluster
+
+My Node has 6 CPU cores for this demo <br/>
+
+```
+kind create cluster --name hpa --image kindest/node:v1.18.4
+```
+
+### Metric Server
+
+* For `Cluster Autoscaler` - On cloud-based clusters, Metric server may already be installed. <br/>
+* For `HPA` - We're using kind
+
+[Metric Server](https://github.com/kubernetes-sigs/metrics-server) provides container resource metrics for use in autoscaling pipelines <br/>
+
+Because I run K8s `1.18` in `kind`, the Metric Server version i need is `0.3.7` <br/>
+We will need to deploy Metric Server [0.3.7](https://github.com/kubernetes-sigs/metrics-server/releases/tag/v0.3.7) <br/>
+I used `components.yaml`from the release page link above. <br/>
+
+<b>Important Note</b> : For Demo clusters (like `kind`), you will need to disable TLS <br/>
+You can disable TLS by adding the following to the metrics-server container args <br/>
+
+<b>For production, make sure you remove the following :</b> <br/>
+
+```
+- --kubelet-insecure-tls
+- --kubelet-preferred-address-types="InternalIP"
+
+```
+
+Deployment: <br/>
+
+
+```
+cd kubernetes\autoscaling
+kubectl -n kube-system apply -f .\components\metric-server\metricserver-0.3.7.yaml
+
+#test 
+kubectl -n kube-system get pods
+
+#note: wait for metrics to populate!
+kubectl top nodes
+
+```
+
+## Example Application
+
+For all autoscaling guides, we'll need a simple app, that generates some CPU load <br/>
+
+* Build the app
+* Push it to a registry
+* Ensure resource requirements are set
+* Deploy it to Kubernetes
+* Ensure metrics are visible for the app
+
+```
+# build
+
+cd kubernetes\autoscaling\components\application
+docker build . -t aimvector/application-cpu:v1.0.0
+
+# push
+docker push aimvector/application-cpu:v1.0.0
+
+# resource requirements
+resources:
+  requests:
+    memory: "50Mi"
+    cpu: "500m"
+  limits:
+    memory: "500Mi"
+    cpu: "2000m"
+
+# deploy 
+kubectl apply -f deployment.yaml
+
+# metrics
+kubectl top pods
+
+```
+
+## Cluster Autoscaler
+
+For cluster autoscaling, you should be able to scale the pods manually and watch the cluster scale. </br>
+Cluster autoscaling stops here. </br>
+For Pod Autoscaling (HPA), continue</br>
+
+## Generate some traffic
+
+Let's deploy a simple traffic generator pod
+
+```
+cd kubernetes\autoscaling\components\application
+kubectl apply -f .\traffic-generator.yaml
+
+# get a terminal to the traffic-generator
+kubectl exec -it traffic-generator sh
+
+# install wrk
+apk add --no-cache wrk
+
+# simulate some load
+wrk -c 5 -t 5 -d 99999 -H "Connection: Close" http://application-cpu
+
+#you can scale to pods manually and see roughly 6-7 pods will satisfy resource requests.
+kubectl scale deploy/application-cpu --replicas 2
+```
+
+## Deploy an autoscaler
+
+```
+# scale the deployment back down to 2
+kubectl scale deploy/application-cpu --replicas 2
+
+# deploy the autoscaler
+kubectl autoscale deploy/application-cpu --cpu-percent=95 --min=1 --max=10
+
+# pods should scale to roughly 6-7 to match criteria of 95% of resource requests
+
+kubectl get pods
+kubectl top pods
+kubectl get hpa/application-cpu  -owide
+
+kubectl describe hpa/application-cpu 
+
+```
+
+## Vertical Pod Autoscaling
+
+The vertical pod autoscaler allows us to automatically set request values on our pods <br/>
+based on recommendations.
+This helps us tune the request values based on actual CPU and Memory usage.<br/>
+
+More [here](./vertical-pod-autoscaling/readme.md)
+