Launching the simple application with Azure Kubernetes Service

In previous few blogs, we have explained about the Kubernetes and container orchestration. Microsoft Azure provides the hosted Kubernetes service. To create the basic Kubernetes Cluster on Azure please visit our previous blog.
In this blog, I will launch a simple application on Azure Container Service.

Pre-requisite

• Kubernetes Cluster
• Kubectl utility
• Deployment and Services in Kubernetes
• Azure CLI

Application: Hello World

This is a simple hello-world application. We will be creating the 5 deployments of the app and external load balancer service to access the app.

Before that please make sure Azure CLI is installed and kubectl is configured with your Kubernetes Cluster.

To make sure kubectl is configured with Azure K8S cluster use following command:

az aks get-credentials --name crK8sCluster --resource-group k8sResourceGroup

Modify --nameand according--resource-group to the cluster configuration. (You will get this when you created the cluster)

$ kubectl get nodes
NAME                       STATUS    ROLES     AGE       VERSION
aks-nodepool1-83648360-0   Ready     agent     51d       v1.7.7

Now the cluster is configured properly.

Let’s check deployment.yml for creating the application:

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: hello-world
  labels:
    app: hello-world
    ver: v1
spec:
  replicas: 5
  selector:
    matchLabels:
      app: hello-world
      ver: v1
  template:
    metadata:
      labels:
        app: hello-world
        ver: v1
    spec:
      containers:
      - name: hello-world
        image: kubejack/helloworld:latest
        imagePullPolicy: Always
        ports:
        - containerPort: 3000

This is the deployment specifications for the hello-world application. And we exposed the app on container port.3000 But to access the app it is required to have external service.

For this, external load balancer service is required. The service will create the external load balancer on Azure and expose the application to the internet.

service.yml:

apiVersion: v1
kind: Service
metadata:
  name: hello-world-svc
  labels:
    name: hello-world-svc
spec:
  type: LoadBalancer
  ports:
    - port: 80
      targetPort: 3000
      protocol: TCP
  selector:
    app: hello-world
    ver: v1

To know more the services please view our blog for services.

Let’s create the deployment and service:

kubectl create -f deployment.yml

and

kubectl create -f service.yml

You will get :

$ kubectl get po -o wide 
NAME                                       READY     STATUS              RESTARTS   AGE       IP            NODE
bitcoin-core-deployment-2058282966-cwchl   1/1       Running             51         45d       10.244.0.7    aks-nodepool1-83648360-0
cr-development-jenkins-2645363986-99n88    1/1       Running             0          34d       10.244.0.22   aks-nodepool1-83648360-0
hello-world-493621601-brnw9                0/1       ContainerCreating   0          30s       <none>        aks-nodepool1-83648360-0
hello-world-493621601-h7qg1                0/1       ContainerCreating   0          30s       <none>        aks-nodepool1-83648360-0
hello-world-493621601-knsm5                0/1       ContainerCreating   0          30s       <none>        aks-nodepool1-83648360-0
hello-world-493621601-qjg7d                0/1       ContainerCreating   0          30s       <none>        aks-nodepool1-83648360-0
hello-world-493621601-tj379                0/1       ContainerCreating   0          30s       <none>        aks-nodepool1-83648360-0

After few seconds,

$ kubectl get po
NAME                                       READY     STATUS    RESTARTS   AGE
hello-world-493621601-brnw9                1/1       Running   0          1m
hello-world-493621601-h7qg1                1/1       Running   0          1m
hello-world-493621601-knsm5                1/1       Running   0          1m
hello-world-493621601-qjg7d                1/1       Running   0          1m
hello-world-493621601-tj379                1/1       Running   0          1m

All the pods will be in running state.

But to access the application we need to check if service exposed the load balancer and given the external IP or not.

$ kubectl get svc 
NAME                           TYPE           CLUSTER-IP     EXTERNAL-IP      PORT(S)          AGE
hello-world-svc                LoadBalancer   10.0.108.140   52.170.233.129   80:30558/TCP     1m
kubernetes                     ClusterIP      10.0.0.1       <none>           443/TCP          51d

Here you can see the external IP exposed 52.170.233.129.

Now its time to verify if the application is running on specified IP or not.
With the curl command lets check it:

$ curl http://52.170.233.129
Hello World!

It’s working. This is the simple way to launch the application with Azure Kubernetes Service.

To delete the application:

$ kubectl delete -f deployment.yml
$ kubectl delete -f service.yml 

It will delete all resources that we have created so far.