To demonstrate independent scaling, let's use the guestbook example that we used in the previous chapter. Let's follow these steps to learn how to implement independent scaling: 

1. Install the guestbook by running the kubectl create command in the Azure command line:

kubectl create -f https://raw.githubusercontent.com/kubernetes/examples/master/guestbook/all-in-one/guestbook-all-in-one.yaml

2. After you have entered the preceding command, you should see the following output in your command-line output:

ab443838-9b3e-4811-b287-74e417a9@Azure:~$ kubectl create -f https://raw.githubusercontent.com/kubernetes/examples/master/guestbook/all-in-one/guestbook-all-in-one.yaml
service/redis-master created
deployment.apps/redis-master created
service/redis-slave created
deployment.apps/redis-slave created
service/frontend created
deployment.apps/frontend created

3. After a few minutes, you should get the following output in which you will see that none of the containers are accessible from the internet, and no external IP is assigned: 

ab443838-9b3e-4811-b287-74e417a9@Azure:~$ kc get all
NAME READY STATUS RESTARTS AGE
pod/frontend-56f7975f44-7sdn5 1/1 Running 0 1m
pod/frontend-56f7975f44-hscn7 1/1 Running 0 1m
pod/frontend-56f7975f44-pqvbg 1/1 Running 0 1m
pod/redis-master-6b464554c8-8nv4s 1/1 Running 0 1m
pod/redis-slave-b58dc4644-597qt 1/1 Running 0 1m
pod/redis-slave-b58dc4644-xtdkx 1/1 Running 0 1m

NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/frontend ClusterIP 10.0.174.190 <none> 80/TCP 1m
service/kubernetes ClusterIP 10.0.0.1 <none> 443/TCP 3d
service/redis-master ClusterIP 10.0.208.204 <none> 6379/TCP 1m
service/redis-slave ClusterIP 10.0.225.59 <none> 6379/TCP 1m

NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
deployment.apps/frontend 3 3 3 3 1m
deployment.apps/redis-master 1 1 1 1 1m
deployment.apps/redis-slave 2 2 2 2 1m

NAME DESIRED CURRENT READY AGE
replicaset.apps/frontend-56f7975f44 3 3 3 1m
replicaset.apps/redis-master-6b464554c8 1 1 1 1m
replicaset.apps/redis-slave-b58dc4644 2 2 2 1m

4. Expose the frontend to the public internet by default using the following command:

kc get -o yaml svc/frontend > frontend-service.yaml
code frontend-service.yaml

5. Edit the frontend-service.yaml file to set the labels, ports, and selector, which should appear as follows (or you can cut and paste the following):

apiVersion: v1
kind: Service
metadata:
 labels:
 app: guestbook
 tier: frontend
 name: frontend
spec:
 ports:
 - port: 80
 protocol: TCP
 targetPort: 80
 selector:
 app: guestbook
 tier: frontend
 type: LoadBalancer

6. Save the file and recreate the frontend service so that we can access it publicly by deleting the frontend service and recreating it as follows:

kubectl delete -f frontend-service.yaml
kubectl create -f frontend-service.yaml

7. Use the following command to get the public IP to access the application via the internet:

kubectl get svc

You will get the following output. You need to look for the IP displayed under the EXTERNAL-IP column:

NAME           TYPE           CLUSTER-IP     EXTERNAL-IP     PORT(S)        AGE
frontend       LoadBalancer   10.0.196.116   <EXTERNAL-IP>   80:30063/TCP   2m

8. Type the IP address from the preceding output into your browser navigation bar as follows: http://<EXTERNAL-IP>/. The result of this is shown in the following screenshot:

The familiar guestbook sample should be visible. You have successfully publically accessed the guestbook.