build-and-deploy-simple-guestbook-app

Build-and-Deploy-Simple-Guestbook-App

Guestbook is a simple web application that I have build and deployed with Docker and Kubernetes. The application consists of a web front end that will have a text input where one can enter any text and submit it. For all of these, I have created Kubernetes Deployments and Pods. Then I applied Horizontal Pod Scaling to the Guestbook application and finally worked on Rolling Updates and Rollbacks.

I exported my namespace as an environment variable so that it could be used in subsequent commands:

• export MY_NAMESPACE=sn-labs-$USERNAME

Build the guestbook app using the Docker Build command:

• docker build . -t us.icr.io/$MY_NAMESPACE/guestbook:v1

Push the image to IBM Cloud Container Registry:

• docker push us.icr.io/$MY_NAMESPACE/guestbook:v1

Verify that the image was pushed successfully:

• ibmcloud cr images
• View crimages.png

Apply the deployment using:

• kubectl apply -f deployment.yml

Open a New Terminal and enter the below command to view your application:

• kubectl port-forward deployment.apps/guestbook 3000:3000
• View app.png

Autoscale the Guestbook deployment:

• kubectl autoscale deployment guestbook --cpu-percent=5 --min=1 --max=10

To check the current status of the newly-made HorizontalPodAutoscaler, by running:

• kubectl get hpa guestbook
• View hpa.png

Enter the below command to generate load on the app to observe the autoscaling:

• kubectl run -i --tty load-generator --rm --image=busybox:1.36.0 --restart=Never -- /bin/sh -c "while sleep 0.01; do wget -q -O- https://ayusshgupta2-3000.theiaopenshiftnext-0-labs-prod-theiaopenshift-4-tor01.proxy.cognitiveclass.ai/; done"

Run the below command to observe the replicas increase in accordance with the autoscaling:

• kubectl get hpa guestbook --watch
• View hpa2.png

To perform Rolling Updates and Rollbacks on the Guestbook application, follow the below steps:

1. Update the title and header in index.html to any other suitable title and header like Guestbook - v2 & Guestbook - v2.

   Run the below command to build and push your updated app image:

   • docker build . -t us.icr.io/$MY_NAMESPACE/guestbook:v1 && docker push us.icr.io/$MY_NAMESPACE/guestbook:v1

2. Update the values of the CPU in the deployment.yml to cpu: 5m and cpu: 2m as below:

   Apply the changes to the deployment.yml file:

   • kubectl apply -f deployment.yml
   • View deployment.yml

3. Open a new terminal and run the port-forward command again to start the app:

   • kubectl port-forward deployment.apps/guestbook 3000:3000
   • View up-app.png

4. Run the below command to see the details of Revision of the deployment rollout:

   • kubectl rollout history deployments guestbook --revision=2
   • View rev.png

5. Run the below command to get the replica sets and observe the deployment that is being used now:

   • kubectl get rs

6. Run the below command to undo the deploymnent and set it to Revision 1:

   • kubectl rollout undo deployment/guestbook --to-revision=1

7. Run the below command to get the replica sets after the Rollout has been undone. The deployment being used would have changed as below:

   • kubectl get rs
   • View rs.png