Deploying an application

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KB0049702

Deploying an application


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Objective

OVHcloud Managed Kubernetes service provides you with Kubernetes clusters without the hassle of installation or operation. This guide will explain how to deploy a simple Hello World application on a OVHcloud Managed Kubernetes cluster.

Requirements

  • an OVHcloud Managed Kubernetes cluster
  • at least one node on the cluster (see the ordering a node guide for details)
  • a well configured kubectl (see the configuring kubectl guide for details)

When a LoadBalancer Service resource is created inside a Managed Kubernetes cluster, an associated Public Cloud Load Balancer is automatically created, allowing public access to your K8S application. The Public Cloud Load Balancer service is hourly charged and will appear in your Public Cloud project. For more information, please refer to the following documentation: Network Load Balancer price.

Instructions

Step 1 - Deploy your first application

The following command will deploy a simple application (nginx image) using a Kubernetes Deployment and a Kubernetes Service.

Create a new namespace:

kubectl create ns hello-app

Create a hello.yml file for our ovhplatform/hello Docker image:

apiVersion: v1
kind: Service
metadata:
  name: hello-world
  labels:
    app: hello-world
spec:
  type: LoadBalancer
  ports:
  - port: 80
    targetPort: 80
    protocol: TCP
    name: http
  selector:
    app: hello-world
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: hello-world-deployment
  labels:
    app: hello-world
spec:
  replicas: 1
  selector:
    matchLabels:
      app: hello-world
  template:
    metadata:
      labels:
        app: hello-world
    spec:
      containers:
      - name: hello-world
        image: ovhplatform/hello
        ports:
        - containerPort: 80

And apply the file:

kubectl apply -f hello.yml -n hello-app

After applying the YAML file, a new hello-world service and the corresponding hello-world-deployment deployment are created in the hello-app namespace:

$ kubectl apply -f hello.yml -n hello-app
service/hello-world created
deployment.apps/hello-world-deployment created

The application you have just deployed is a simple Nginx server with a single static Hello World page. Basically it just deploys the Docker image ovhplatform/hello.

Step 2 - List the pods

You have just deployed a hello-world service in a pod in your worker node. Let's verify that everything is correct by listing the pods.

kubectl get pods -n hello-app -l app=hello-world

You should see your newly created pod:

$ kubectl get pods -n hello-app -l app=hello-world
NAME                                           READY     STATUS    RESTARTS   AGE
hello-world-deployment-d98c6464b-7jqvg         1/1       Running   0          47s

In this tutorial, we chose to create a special namespace to isolate our application.

But if you want to use the default namespace instead, it's the default Kubernetes namespace so you don't need to specify it in your kubectl commands.

Step 3 - List the deployments

You can also verify that the deployment is active:

kubectl get deploy -n hello-app -l app=hello-world

And you will see the hello-service-deployment:

$ kubectl get deploy -n hello-app -l app=hello-world
NAME                          DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
hello-world-deployment        1         1         1            1           1m

Step 4 - List the services

Now, you will use kubectl to view your service:

kubectl get services -n hello-app -l app=hello-world

You should see your newly created service:

$ kubectl get services -n hello-app -l app=hello-world
NAME          TYPE           CLUSTER-IP     EXTERNAL-IP    PORT(S)        AGE
hello-world   LoadBalancer   10.3.234.211   51.178.69.47   80:31885/TCP   6m54s

In case you get <pending> under EXTERNAL-IP, it may take a minute or two to provision the LoadBalancer, so try again in a few moments.

Step 5 - Test your service

Retrieve the URL of the hello-world application:

$ export SERVICE_URL=$(kubectl get svc hello-world -n hello-app -o jsonpath='{.status.loadBalancer.ingress[].ip}')

$ echo "http://$SERVICE_URL/"
http://135.125.83.30/

Copy/paste the URL in your browser to see your new running hello-world application:

Testing your service

You can also test the newly created service, in command line, with curl:

curl $SERVICE_URL

You should see your newly created service:

curl $SERVICE_URL
<!doctype html>

<html>
<head>
<title>OVH K8S</title>
</head>
<body>
<div class="title">
<p>Hello from Kubernetes!</p>
<img src="./ovh.svg"/>
</div>
</body>
</html>

If you have an error message "Failed to connect to 135.125.83.30 port 80: Connection refused", it's normal. The service is starting, so you have to wait a few seconds in order to test it again.

Step 6 - Clean up

At the end, you can clean up by deleting the service and the deployment.

Let's delete the namespace (deleting the namespace will delete all resources created within it, including the deployment and the service):

kubectl delete ns hello-app

If you list the services, the deployments and the pods, you will see that hello-world doesn't exist anymore:

$ kubectl delete service hello-world -n hello-app
namespace "hello-app" deleted

$ kubectl get services -l app=hello-world -n hello-app
No resources found in hello-app namespace.

$ kubectl get deployments -n hello-app -l app=hello-world
No resources found in hello-app namespace.

$ kubectl get pods -n hello-app -l app=hello-world
No resources found in hello-app namespace.

Go further

To learn more about using your Kubernetes cluster the practical way, we invite you to look at our OVHcloud Managed Kubernetes doc site.

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