Deploy-an-application

This guide outlines the steps to deploy an application to a Kubernetes cluster managed by Utho, along with example outputs for each command to help verify execution.

Prerequisites

To follow this guide, you must:

• Install docker, the docker command-line tool
• Install kubectl, the Kubernetes command-line tool.

1. Access the Kubernetes Cluster

• Download the kubeconfig file from the cluster management section on Utho’s platform.

• Use the following command to configure your local system to use the Kubernetes cluster:

  export KUBECONFIG=/path/to/kubeconfig

• Verify the cluster connection:

  kubectl cluster-info

  Sample Output :

  Kubernetes control plane is running at https://123.45.67.89:6443
  CoreDNS is running at https://123.45.67.89:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

2. Prepare Your Application for Deployment

• Ensure your application is containerized. Build and push your application image to a container registry. Example Docker commands:

  docker build -t <your-image-name>:<tag> .
  docker push <registry-url>/<your-image-name>:<tag>

  Sample Output :

  Sending build context to Docker daemon  10.24kB
  Step 1/4 : FROM nginx
  ---> 4bb46517cac3
  Step 2/4 : COPY . /usr/share/nginx/html
  ---> Using cache
  Step 3/4 : EXPOSE 80
  ---> Using cache
  Step 4/4 : CMD ["nginx", "-g", "daemon off;"]
  ---> Using cache
  Successfully built d9f2e4d3a356
  Successfully tagged <registry-url>/<your-image-name>:<tag>
  
  The push refers to repository [<registry-url>/<your-image-name>]
  abc1234: Pushed
  latest: digest: sha256:abcdef1234567890 size: 1573

3. Create Kubernetes Deployment YAML

• Prepare a YAML file for your application’s deployment and service. deployment.yaml

  apiVersion: apps/v1
  kind: Deployment
  metadata:
    name: my-app
    labels:
      app: my-app
  spec:
    replicas: 3
    selector:
      matchLabels:
        app: my-app
    template:
      metadata:
        labels:
          app: my-app
      spec:
        containers:
        - name: my-app-container
          image: <registry-url>/<your-image-name>:<tag>
          ports:
          - containerPort: 80
  ---
  apiVersion: v1
  kind: Service
  metadata:
    name: my-app-service
  spec:
    selector:
      app: my-app
    ports:
      - protocol: TCP
        port: 80
        targetPort: 80
    type: LoadBalancer

4. Apply the YAML File

• Deploy your application using the YAML file:

  kubectl apply -f deployment.yaml

  Sample Output :

  deployment.apps/my-app created
  service/my-app-service created

• Verify the deployment and service:

  kubectl get deployments

  Sample Output :

  NAME      READY   UP-TO-DATE   AVAILABLE   AGE
  my-app    3/3     3            3           2m

  kubectl get pods

  Sample Output :

  NAME                     READY   STATUS    RESTARTS   AGE
  my-app-658f89f469-abcde  1/1     Running   0          2m
  my-app-658f89f469-fghij  1/1     Running   0          2m
  my-app-658f89f469-klmno  1/1     Running   0          2m

  kubectl get services

  Sample Output :

  NAME              TYPE           CLUSTER-IP      EXTERNAL-IP      PORT(S)        AGE
  my-app-service    LoadBalancer   10.96.245.195   123.45.67.89     80:30382/TCP   2m

5. Monitor the Deployment

• Check the logs of your application pods to ensure everything is working correctly:

  kubectl logs -f <pod-name>

  Sample Output :

  Starting server on port 80
  Server running at http://0.0.0.0:80

• Monitor the health of your application:

  kubectl get pods --watch

  Sample Output :

  NAME                     READY   STATUS    RESTARTS   AGE
  my-app-658f89f469-abcde  1/1     Running   0          5m
  my-app-658f89f469-fghij  1/1     Running   0          5m
  my-app-658f89f469-klmno  1/1     Running   0          5m

6. Access Your Application

• Note the external IP of the LoadBalancer service:

  kubectl get service my-app-service

  Sample Output :

  NAME              TYPE           CLUSTER-IP      EXTERNAL-IP      PORT(S)        AGE
  my-app-service    LoadBalancer   10.96.245.195   123.45.67.89     80:30382/TCP   2m

• Test the application:

  curl http://123.45.67.89

  Sample Output :

  Welcome to My App!

7. Scale the Application (Optional)

• To scale the number of replicas:

  kubectl scale deployment my-app --replicas=5

  Sample Output :

  deployment.apps/my-app scaled

• Verify the scaling:

  kubectl get pods

  Sample Output :

  NAME                     READY   STATUS    RESTARTS   AGE
  my-app-658f89f469-abcde  1/1     Running   0          2m
  my-app-658f89f469-fghij  1/1     Running   0          2m
  my-app-658f89f469-klmno  1/1     Running   0          2m
  my-app-658f89f469-pqrst  1/1     Running   0          30s
  my-app-658f89f469-uvwxy  1/1     Running   0          30s

8. Update the Application (Optional)

• Update the application with a new container image:

  kubectl set image deployment/my-app my-app-container=<new-image-url>

  Sample Output :

  deployment.apps/my-app image updated

• Monitor the rollout status:

  kubectl rollout status deployment/my-app

  Sample Output :

  deployment "my-app" successfully rolled out

9. Clean Up Resources

• To delete the deployment and service:

  kubectl delete -f deployment.yaml

  Sample Output :

  deployment.apps "my-app" deleted
  service "my-app-service" deleted

• Verify resource deletion:

  kubectl get all

  Sample Output :

  No resources found in default namespace.

By following these steps and verifying with the sample outputs, you can successfully deploy your application on Utho’s Kubernetes cluster.