Tutorial: Deploy Linux applications in Azure Kubernetes Service on Azure Stack HCI

Applies to: AKS on Azure Stack HCI, AKS runtime on Windows Server 2019 Datacenter

In this tutorial, you deploy a multi-container application that includes a web front end and a Redis database instance in your Azure Kubernetes Service on Azure Stack HCI cluster. You then see how to test and scale your application.

This tutorial assumes a basic understanding of Kubernetes concepts. For more information, see Kubernetes core concepts for Azure Kubernetes Service on Azure Stack HCI.

Before you begin

Verify you have the following requirements ready:

  • An Azure Kubernetes Service on Azure Stack HCI cluster with at least one Linux worker node that is up and running.
  • A kubeconfig file to access the cluster.
  • Have the Azure Kubernetes Service on Azure Stack HCI PowerShell module installed.
  • Run the commands in this document in a PowerShell administrative window.
  • Ensure that OS-specific workloads land on the appropriate container host. If you have a mixed Linux and Windows worker nodes Kubernetes cluster, you can either use node selectors or taints and tolerations. For more information, see using node selectors and taints and tolerations.

Deploy the application

A Kubernetes manifest file defines a desired state for the cluster, such as what container images to run. In this quickstart, a manifest is used to create all objects needed to run the Azure vote application. This manifest includes two Kubernetes deployments - one for the sample Azure Vote Python applications, and the other for a Redis instance. Two Kubernetes services are also created - an internal service for the Redis instance, and an external service to access the Azure Vote application from the internet.

Create a file named azure-vote.yaml and copy in the following YAML definition.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: azure-vote-back
spec:
  replicas: 1
  selector:
    matchLabels:
      app: azure-vote-back
  template:
    metadata:
      labels:
        app: azure-vote-back
    spec:
      nodeSelector:
        "beta.kubernetes.io/os": linux
      containers:
      - name: azure-vote-back
        image: redis
        resources:
          requests:
            cpu: 100m
            memory: 128Mi
          limits:
            cpu: 250m
            memory: 256Mi
        ports:
        - containerPort: 6379
          name: redis
---
apiVersion: v1
kind: Service
metadata:
  name: azure-vote-back
spec:
  ports:
  - port: 6379
  selector:
    app: azure-vote-back
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: azure-vote-front
spec:
  replicas: 1
  selector:
    matchLabels:
      app: azure-vote-front
  template:
    metadata:
      labels:
        app: azure-vote-front
    spec:
      nodeSelector:
        "beta.kubernetes.io/os": linux
      containers:
      - name: azure-vote-front
        image: mcr.microsoft.com/azuredocs/azure-vote-front:v1
        resources:
          requests:
            cpu: 100m
            memory: 128Mi
          limits:
            cpu: 250m
            memory: 256Mi
        ports:
        - containerPort: 80
        env:
        - name: REDIS
          value: "azure-vote-back"
---
apiVersion: v1
kind: Service
metadata:
  name: azure-vote-front
spec:
  type: LoadBalancer
  ports:
  - port: 80
  selector:
    app: azure-vote-front

Deploy the application using the kubectl apply command and specify the name of your YAML manifest:

kubectl apply -f azure-vote.yaml

The following example output shows the Deployments and Services created successfully:

deployment "azure-vote-back" created
service "azure-vote-back" created
deployment "azure-vote-front" created
service "azure-vote-front" created

Test the application

When the application runs, a Kubernetes service exposes the application front end to the internet. This process can take a few minutes to complete.

To monitor progress, use the kubectl get service command with the --watch argument.

kubectl get service azure-vote-front --watch

Initially the EXTERNAL-IP for the azure-vote-front service is shown as pending.

NAME               TYPE           CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
azure-vote-front   LoadBalancer   10.0.37.27      <pending>     80:30572/TCP   22m

When the EXTERNAL-IP address changes from pending to an actual public IP address, use CTRL-C to stop the kubectl watch process. The following example output shows a valid public IP address assigned to the service:

NAME               TYPE           CLUSTER-IP   EXTERNAL-IP     PORT(S)        AGE
azure-vote-front   LoadBalancer   10.0.37.27   52.179.23.131   80:30572/TCP   24m

To see the Azure Vote app in action, open a web browser to the external IP address of your service.

Image of Kubernetes cluster on Azure

Scale application pods

We have created a single replica of the Azure Vote front end and Redis instance. To see the number and state of pods in your cluster, use the kubectl get command as follows:

kubectl get pods -n default

The following example output shows one front end pod and one back-end pod:

NAME                                READY     STATUS    RESTARTS   AGE
azure-vote-back-6bdcb87f89-g2pqg    1/1       Running   0          25m
azure-vote-front-84c8bf64fc-cdq86   1/1       Running   0          25m

To change the number of pods in the azure-vote-front deployment, use the kubectl scale command. The following example increases the number of front end pods to 5:

kubectl scale --replicas=5 deployment/azure-vote-front

Run kubectl get pods again to verify that additional pods have been created. After a minute or so, the additional pods are available in your cluster:

kubectl get pods -n default

Name                                READY   STATUS    RESTARTS   AGE
azure-vote-back-6bdcb87f89-g2pqg    1/1     Running   0          31m
azure-vote-front-84c8bf64fc-cdq86   1/1     Running   0          31m
azure-vote-front-84c8bf64fc-56h64   1/1     Running   0          80s
azure-vote-front-84c8bf64fc-djkp8   1/1     Running   0          80s
azure-vote-front-84c8bf64fc-jmmvs   1/1     Running   0          80s
azure-vote-front-84c8bf64fc-znc6z   1/1     Running   0          80s

Next steps