feat: add hpa-vpa (#23)

15-hpa-vpa/01-hpa.yml

@@ -0,0 +1,46 @@
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: hpa-example
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: hpa-example
+  template:
+    metadata:
+      labels:
+        app: hpa-example
+    spec:
+      containers:
+        - name: hpa-example
+          image: k8s.gcr.io/hpa-example
+          ports:
+            - containerPort: 80
+          resources:
+            requests:
+              cpu: 200m
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: hpa-example
+spec:
+  ports:
+    - port: 80
+  selector:
+    app: hpa-example
+---
+apiVersion: autoscaling/v1
+kind: HorizontalPodAutoscaler
+metadata:
+  name: hpa-example
+spec:
+  maxReplicas: 10
+  minReplicas: 1
+  scaleTargetRef:
+    apiVersion: apps/v1
+    kind: Deployment
+    name: hpa-example
+  targetCPUUtilizationPercentage: 50

15-hpa-vpa/02-hpa.yml

@@ -1,13 +0,0 @@
----
-apiVersion: autoscaling/v1
-kind: HorizontalPodAutoscaler
-metadata:
-  name: simple-hpa
-spec:
-  maxReplicas: 10
-  minReplicas: 3
-  scaleTargetRef:
-    apiVersion: extensions/v1beta1
-    kind: Deployment
-    name: simple-deployment
-targetCPUUtilizationPercentage: 80

15-hpa-vpa/README.md

@@ -1,5 +1,7 @@
 # HPA, VPA
 
+## HPA
+
 HPA means `Horizontal Pod Autoscaler`. It automatically scales the number of pods in a replication controller, deployment or replica set based on observed CPU utilization (or, with custom metrics support, on some other application-provided metrics).
 
 Let's take an example with CPU usage:
@@ -13,9 +15,9 @@ spec:
   maxReplicas: 10
   minReplicas: 3
   scaleTargetRef:
-    apiVersion: extensions/v1beta1
+    apiVersion: apps/v1
     kind: Deployment
-    name: simple-deployment
+    name: my-deployment
 targetCPUUtilizationPercentage: 80
 ```
 
@@ -24,3 +26,71 @@ targetCPUUtilizationPercentage: 80
   * `minReplicas`: the minimum number of pods running
   * `scaleTargetRef`: what this HPA targets, here a `Deployment` named `simple-deployment`
 * `targetCPUUtilizationPercentage`: the percentage of CPU utilization to cross to activate the HPA
+
+Let's see an HPA in action. This exemple is inspired by [the official Kubernetes documentation](https://kubernetes.io/docs/tasks/run-application/horizontal-pod-autoscale-walkthrough/).
+
+To see it in action, we need to have a workload that consumes some CPU. We'll use an image that is CPU intensive: https://hub.docker.com/r/googlecontainer/hpa-example.
+
+This image computes the square root of numbers:
+
+```php
+<?php
+  $x = 0.0001;
+  for ($i = 0; $i <= 1000000; $i++) {
+    $x += sqrt($x);
+  }
+  echo "OK!";
+?>
+```
+
+First, you need to active the [`metric-server`](https://github.com/kubernetes-incubator/metrics-server/) on minikube:
+
+```sh
+minikube addons enable metrics-server
+```
+
+Review and apply the file [01-hpa.yml](./01-hpa.yml).
+
+Now let's generate some load on our service:
+
+```sh
+kubectl run -i --tty load-generator --image=busybox /bin/sh
+```
+
+Then run in this terminal:
+
+```sh
+while true; do wget -q -O- http://hpa-example; done
+```
+
+In another terminal look at the state of the pods and the hpa, remember the `-w` flag on `kubectl`.
+
+Wait a bit and see how it changes the pods and the hpa.
+
+Stop the load generator, again, wait a bit and see how it changes the pods and the hpa.
+
+## VPA
+
+VPA means `Vertical Pod Autoscaler`. It automatically find the right resources for pods in a replication controller, deployment or replica set based on observed CPU utilization.
+
+This feature is in beta, understand you can install it in your cluster but it's not integrate with the standard k8s source code.
+
+If you are adventurous you can try it by:
+
+1. Install [metrics-server](https://github.com/kubernetes-incubator/metrics-server#deployment).
+1. Install the [vpa](https://github.com/kubernetes/autoscaler/tree/master/vertical-pod-autoscaler).
+1. Try the exemple from the [vpa github repo](https://github.com/kubernetes/autoscaler/tree/master/vertical-pod-autoscaler#test-your-installation)
+
+## Exercices
+
+Nothing to see here.
+
+## Clean up
+
+```bash
+kubectl delete service,deployment,pod,crd,vpa --all
+```
+
+## Links
+
+* https://kubernetes.io/docs/tasks/run-application/horizontal-pod-autoscale/