Using a Statefulset to demo VCD cloud and storage providers.

This post uses a statefulset to deploy nginx with pvc and load balancer services into a Kubernetes cluster running in VMware Cloud Director enabled with Container Service Extension.

VCD has a cloud provider named vmware-cloud-director-ccm-0 and a CSI provider named csi-vcd-controllerplugin-0.

If you sent the following command to a Kubernetes cluster

kubectl get po -n kube-system

You would see output like this

csi-vcd-controllerplugin-0                  3/3     Running   0          11h
csi-vcd-nodeplugin-lh2gs                    2/2     Running   0          13h
vmware-cloud-director-ccm-99fd59464-79z8r   1/1     Running   0          11h

Contents of web-statefulset.yaml, available on my GitHub here.

apiVersion: v1
kind: Service
metadata:
  name: nginx-service
  namespace: web-statefulset
spec:
  selector:
    app: nginx
  ports:
    - port: 80
      targetPort: 80
  type: LoadBalancer
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: web-statefulset
  namespace: web-statefulset
spec:
  selector:
    matchLabels:
      app: nginx
  serviceName: "nginx-service"
  replicas: 1
  template:
    metadata:
      labels:
        app: nginx
    spec:
      terminationGracePeriodSeconds: 10
      containers:
      - name: nginx
        image: k8s.gcr.io/nginx-slim:0.8
        ports:
        - containerPort: 80
          name: nginx
        volumeMounts:
        - name: www
          mountPath: /usr/share/nginx/html
  volumeClaimTemplates:
  - metadata:
      name: www
    spec:
      accessModes: [ "ReadWriteOnce" ]
      storageClassName: "vcd-disk-dev"
      resources:
        requests:
          storage: 1Gi

Lets deploy into a new namespace, for that we create a new namespace first.

kubectl create ns web-statefulset

Deploy the statefulset with the following command

kubectl apply -f web-statefulset.yaml

You’ll see named disks and ingress services create in VCD and Avi respectively.

If you tried to access the nginx webpage using the service IP address, you wouldn’t see any web page, although the connection is working. This is because the nginx app using the /usr/share/nginx/html mount point to an empty PVC. We need to copy a basic index.html into that directory to get a webpage.

We can do that by logging into the pod and downloading a sample index.html for nginx.

kubectl exec -it web-statefulset-0 -n web-statefulset -- bash

curl https://raw.githubusercontent.com/hugopow/cse/main/index.html -o /usr/share/nginx/html/index.html

Now when you connect to the external IP you would get a very simple webpage.

The index.html file is stored on /usr/share/nginx/html/index.html, which is mounted to /sdb1 backed by the PVC.

Author: Hugo Phan

@hugophan View all posts by Hugo Phan