Performing a Rolling Update of an Application in Kubernetes

In this hands-on lab, you will be presented with a 3-node cluster. You will need to deploy your application, so you can begin serving your end users. You will deploy the image from `linuxacademycontent/kubeserve:v1` and then verify the deployment was successful. Once your application is running and serving clients, you will perform a rolling update, making sure the rollout is successful and there is no downtime for your end users. You will make use of the `kubectl` command-line tool to perform all operations, in combination with the `set image` command to perform the rolling update to the new version. When you have verified the end users are now using version 2 of the app versus version 1, you may consider this hands-on lab complete.

Learning Objectives

Successfully complete this lab by achieving the following learning objectives:

Create and Roll Out Version 1 of the Application, and Verify a Successful Deployment

Create the kubeserve-deployment.yaml file, and add the following YAML to create your deployment:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: kubeserve
spec:
  replicas: 3
  selector:
    matchLabels:
      app: kubeserve
  template:
    metadata:
      name: kubeserve
      labels:
        app: kubeserve
    spec:
      containers:
      - image: linuxacademycontent/kubeserve:v1
        name: app

Use the following command to create the deployment:

kubectl apply -f kubeserve-deployment.yaml --record

Use the following command to verify the deployment was successful:
```
kubectl rollout status deployments kubeserve
```
Use the following command to verify the app is at the correct version:
```
kubectl describe deployment kubeserve
```

Scale Up the Application to Create High Availability

Use the following command to scale up your application to 5 replicas:
```
kubectl scale deployment kubeserve --replicas=5
```
Use the following command to verify the additional replicas have been created:
```
kubectl get pods
```

Create a Service So Users Can Access the Application

Use the following command to create a service for your deployment:

kubectl expose deployment kubeserve --port 80 --target-port 80 --type NodePort

Use the following command to verify the service is present and collect the cluster IP:
```
kubectl get services
```

Perform a Rolling Update to Version 2 of the Application, and Verify Its Success

Use this curl loop command to see the version change as you perform the rolling update:
```
while true; do curl http://<ip-address-of-the-service>; done
```

Use this command to perform the update (while the curl loop is running):

kubectl set image deployments/kubeserve app=linuxacademycontent/kubeserve:v2 --v 6

Use this command to view the additional ReplicaSet created during the update:
```
kubectl get replicasets
```
Use this command to verify all pods are up and running:
```
kubectl get pods
```
Use this command to view the rollout history:
```
kubectl rollout history deployment kubeserve
```

What are Hands-on Labs

Hands-on Labs are real environments created by industry experts to help you learn. These environments help you gain knowledge and experience, practice without compromising your system, test without risk, destroy without fear, and let you learn from your mistakes. Hands-on Labs: practice your skills before delivering in the real world.

Performing a Rolling Update of an Application in Kubernetes

About this Hands-on Lab

Learning Objectives

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