Deploy the Guestbook Application on a TKG Cluster

Deploy the Guestbook application to your TKG cluster and explore Kubernetes.

Deploying the Guestbook application is a useful way to explore Kubernetes. The application uses Deployment and ReplicaSet objects to deploy pods in the default namespace, and exposes these pods using Services. Guestbook data is persisted so that if the application goes down, the data remains. This tutorial uses a dynamic persistent volume claim (PVC) to request persistent storage resources without knowing the details of the underlying storage. The storage used for the PVC is allocated from the storage quota for the vSphere Namespace. Containers by default are ephemeral and stateless. For stateful workloads, a common approach is to create a persistent volume claim (PVC). You can use a PVC to mount the persistent volumes and access storage. The request dynamically provisions a persistent volume object and a matching virtual disk. The claim is bound to the persistent volume. When you delete the claim, the corresponding persistent volume object and the provisioned virtual disk are also deleted.

Prerequisites

Review the following topics:

• Guestbook application tutorial in the Kubernetes documentation
• Provision a TKG cluster.
• Connect to the TKG cluster.

Procedure

1. Log in to the TKG cluster.
2. Create the Guestbook namespace.

   kubectl create namespace guestbook

   Verify:

   kubectl get ns

3. Create role-based access control using the default privileged PSP.

   kubectl create clusterrolebinding default-tkg-admin-privileged-binding --clusterrole=psp:vmware-system-privileged --group=system:authenticated

   Note: If you require more security, apply a RoleBinding on the Guestbook namespace.
4. Verify the storage class, or create one.
   To verify an existing storage class:

   kubectl describe namespace

   Or, if you have vSphere administrator permissions:

   kubectl get storageclass

5. Create the dynamic persistent volume claims (PVCs) YAML files that reference the storage class.
   Use the following YAML files. Update each with the name of the storage class.

   • Redis Leader Persistent Volume Claim
   • Redis Follower Persistent Volume Claim
6. Apply the Guestbook PVCs to the cluster.

   kubectl apply -f redis-leader-pvc.yaml -n guestbook

   kubectl apply -f redis-follower-pvc.yaml -n guestbook

7. Verify the status of the PVCs.

   kubectl get pvc,pv -n guestbook

   The PVCs and persistent volumes (PVs) are listed and available for use.

   NAME                                       STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS         AGE
   persistentvolumeclaim/redis-follower-pvc   Bound    pvc-37b72f35-3de2-4f84-be7d-50d5dd968f62   2Gi        RWO            tkgs-storage-class   66s
   persistentvolumeclaim/redis-leader-pvc     Bound    pvc-2ef51f31-dd4b-4fe2-bf4c-f0149cb4f3da   2Gi        RWO            tkgs-storage-class   66s
   
   NAME                                                CAPACITY   ACCESS MODES   RECLAIM POLICY STATUS   CLAIM                 STORAGECLASS         
   persistentvolume/pvc-2ef51f31-dd4b-4fe2-bf4c   2Gi  RWO            Delete           Bound    guestbook/redis-leader-pvc     tkgs-storage-class
   persistentvolume/pvc-37b72f35-3de2-4f84-be7d   2Gi  RWO            Delete           Bound    guestbook/redis-follower-pvc   tkgs-storage-class

8. Create the Guestbook YAML files.
   Use the following YAML files:

   • Redis Leader Deployment
   • Redis Follower Deployment
   • Redis Leader Service
   • Redis Follower Service
   • Guestbook Frontend Deployment
   • Guestbook Frontend Service
9. Deploy the Guestbook application in its namespace.

   kubectl apply -f . --namespace guestbook

10. Verify creation of the Guestbook resources.

    kubectl get all -n guestbook

    NAME                                                 READY   STATUS              RESTARTS   AGE
    pod/guestbook-frontend-deployment-56fc5b6b47-cd58r   1/1     Running             0          65s
    pod/guestbook-frontend-deployment-56fc5b6b47-fh6dp   1/1     Running             0          65s
    pod/guestbook-frontend-deployment-56fc5b6b47-hgd2b   1/1     Running             0          65s
    pod/redis-follower-deployment-6fc9cf5759-99fgw       1/1     Running             0          65s
    pod/redis-follower-deployment-6fc9cf5759-rhxf7       1/1     Running             0          65s
    pod/redis-leader-deployment-7d89bbdbcf-flt4q         1/1     Running             0          65s
    
    NAME                                 TYPE           CLUSTER-IP       EXTERNAL-IP     PORT(S)        AGE
    service/guestbook-frontend           LoadBalancer   10.10.89.59      10.19.15.99     80:31513/TCP   65s
    service/redis-follower               ClusterIP      10.111.163.189   <none>          6379/TCP       65s
    service/redis-leader                 ClusterIP      10.111.70.189    <none>          6379/TCP       65s
    
    NAME                                            READY   UP-TO-DATE   AVAILABLE   AGE
    deployment.apps/guestbook-frontend-deployment   3/3     3            3           65s
    deployment.apps/redis-follower-deployment       1/2     2            1           65s
    deployment.apps/redis-leader-deployment         1/1     1            1           65s
    
    NAME                                                       DESIRED   CURRENT   READY   AGE
    replicaset.apps/guestbook-frontend-deployment-56fc5b6b47   3         3         3       65s
    replicaset.apps/redis-follower-deployment-6fc9cf5759       2         2         1       65s
    replicaset.apps/redis-leader-deployment-7d89bbdbcf         1         1         1       65s

11. Access the Guestbook web page using the External-IP address of the service/guestbook-frontend load balancer, which in this example is 10.19.15.99.
    You see the Guestbook web interface, and you can enter values into the Guestbook database. If you restart the application, the data is persisted.