In the blog I shall be describing the step by step process to setup a Kubernetes cluster using minikube to run a node js based application in Azure cloud and autoscaling the application using Horizontal Pod AutoScaler.
- Spin up a Standard D4s v3 (4 vcpus, 16 GiB memory) Virtual machine in Azure based on Linux (ubuntu 18.04)
- Putty into the server and sudo su -. Execute all following commands as root.
sudo apt-get update
sudo apt-get install -y apt-transport-https
sudo apt-get install -y virtualbox virtualbox-ext-pack
- Install kubectl
curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add –
sudo touch /etc/apt/sources.list.d/kubernetes.list
echo "deb http://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee -a /etc/apt/sources.list.d/kubernetes.list
sudo apt-get update
sudo apt-get install -y kubectl
- Install minikube
curl -LO https://storage.googleapis.com/minikube/releases/latest/minikube-latest.x86_64.rpm
sudo rpm -ivh minikube-latest.x86_64.rpm
chmod +x minikube && sudo mv minikube /usr/local/bin/
minikube start
- Run the following commands to ensure proper installation.
kubectl api-versions
kubectl get services
- Create a new node js application
apt-get install npm
npm init // this create a new package.json file in the directory- Create an index.js file with the following code.
const http = require(‘http’);
const port = process.env.PORT || 3000;
const server = http.createServer((req, res) => {
res.statusCode = 200;
res.setHeader(‘Content-Type’, ‘text/plain’);
res.end(‘Hello World\n’);
});server.listen(port, () => {
console.log(‘Server running on port: ${port}’);
});
- Create a Dockerfile in the same directory with the following content
FROM node:alpine
RUN mkdir -p /usr/src/app
WORKDIR /usr/src/app
ADD index.js ./
ADD package.json ./
RUN npm install
CMD ["npm", "start"]
Sudo apt-get install docker.io
docker login
docker build -t rtdhaccount/node-application .
docker push rtdhaccount/node-application
- Deploy to kubernetes
- Create a folder called k8s
- Create deployment.yml inside k8s with the following content
apiVersion: extensions/v1
kind: Deployment
metadata:
name: node-application-deployment
spec:
replicas: 1
template:
metadata:
labels:
app: node-application
spec:
containers:
- name: node-application
image: rtdhaccount/node-application
imagePullPolicy: Always
ports:
- containerPort: 3000- Create service.yml inside k8s with the following content
apiVersion: v1
kind: Service
metadata:
name: node-application
labels:
app: node-application
spec:
selector:
app: node-application
ports:
- port: 3000
protocol: TCP
nodePort: 30001
type: LoadBalancer- Verify the service using the following commands
kubectl apply -f k8s
kubectl get services
kubectl get deployments
kubectl get pods
- Access Minikube dashboard. To access the minikube dashboard. Open a new putty window and run
sudo kubectl proxy --address='0.0.0.0' --disable-filter=trueopen a new browser window and enter the url below
where xx.yy.zz.ww is the public ipaddress of your VM.
Ensure that port 8001 is open to inbound traffic in the VM
Incase you get the error :
Unable to start VM: Error getting state for host: machine does not exist
minikube delete
minikube start
- Accessing the node application.Open a new putty window and setup port forwarding like below
sudo ssh -i ~/.minikube/machines/minikube/id_rsa docker@$(minikube ip) -L \*:30001:0.0.0.0:30001And the access your application from the browser window using the url
Ensure that port 30001 is open to inbound traffic in the VM
Incase of any errors in port forwarding
ssh-keygen -f "/root/.ssh/known_hosts" -R "192.168.99.100"- Scaling the cluster using Horizontal pod autoscaler. Create a new file hpa.yml under the k8s folder with the following content
apiVersion: autoscaling/v1
kind: HorizontalPodAutoscaler
metadata:
annotations:
name: node-application
namespace: default
spec:
maxReplicas: 5
minReplicas: 1
scaleTargetRef:
apiVersion: extensions/v1
kind: Deployment
name: node-application
targetCPUUtilizationPercentage: 1
With targetCPUUtilizationPercentage option, we are saying that, Once the cpu load inside observed CPU more than 1%, scale this pod.
kubectl apply -f k8s/hpa.yml- Deploy the metrics-server
kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/download/v0.3.6/components.yaml
kubectl get deployment metrics-server -n kube-system
minikube addons list
minikube addons enable metrics-server
kubectl get hpa- Testing using apache benchmark : Install apache benchmark using the below command
apt-get install apache2-utils
ab -c 500 -n 100000 -t 100000 http://xx.yy.zz.ww:30001/- Observe the pods scaling up using the commands
kubectl get pods
kubectl get hpa
References :
https://matthewpalmer.net/kubernetes-app-developer/articles/install-kubernetes-ubuntu-tutorial.html
Raghu Tirnellai's blog 