GKE Persistent Disks Custom StorageClass

Step-00: Pre-requisites¶

Verify if GKE Cluster is created

Verify if kubeconfig for kubectl is configured in your local terminal

# Configure kubeconfig for kubectl
gcloud container clusters get-credentials <CLUSTER-NAME> --region <REGION> --project <PROJECT>

# Replace Values CLUSTER-NAME, ZONE, PROJECT
gcloud container clusters get-credentials standard-cluster-private-1 --region us-central1 --project kdaida123

Feature: Compute Engine persistent disk CSI Driver
Verify the Feature Compute Engine persistent disk CSI Driver enabled in GKE Cluster.
This is required for mounting the Google Compute Engine Persistent Disks to Kubernetes Workloads in GKE Cluster.

Step-01: Introduction¶

Feaute-1: Create custom Kubernetes StorageClass instead of using predefined one in GKE Cluster. custom storage class gke-pd-standard-rwo-sc
Feature-2: Test allowVolumeExpansion: true in Storage Class
Feature-3: Use reclaimPolicy: Retain in Storage Class and Test it

Step-02: List Kubernetes Storage Classes in GKE Cluster¶

# List Storage Classes
kubectl get sc

Step-03: 00-storage-class.yaml¶

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata: 
  name: gke-pd-standard-rwo-sc
provisioner: pd.csi.storage.gke.io
volumeBindingMode: WaitForFirstConsumer 
allowVolumeExpansion: true
reclaimPolicy: Retain 
parameters:
  type: pd-balanced

# STORAGE CLASS 
# 1. A StorageClass provides a way for administrators 
# to describe the "classes" of storage they offer.
# 2. Here we are offering GCP PD Storage for GKE Cluster

Step-04: 01-persistent-volume-claim.yaml¶

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mysql-pv-claim
spec: 
  accessModes:
    - ReadWriteOnce
  storageClassName: gke-pd-standard-rwo-sc
  resources: 
    requests:
      storage: 4Gi

Step-05: Other Kubernetes YAML Manifests¶

No changes to other Kubernetes YAML Manifests
They are same as previous section
02-UserManagement-ConfigMap.yaml
03-mysql-deployment.yaml
04-mysql-clusterip-service.yaml
05-UserMgmtWebApp-Deployment.yaml
06-UserMgmtWebApp-LoadBalancer-Service.yaml

Step-06: Deploy kube-manifests¶

# Deploy Kubernetes Manifests
kubectl apply -f kube-manifests/

# List Storage Classes
kubectl get sc
Observation: 
1. You should find the new custom storage class object created with name as "gke-pd-standard-rwo-sc"

# List PVC
kubectl get pvc

# List PV
kubectl get pv

# List ConfigMaps
kubectl get configmap

# List Deployments
kubectl get deploy

# List Pods
kubectl get pods

# List Services
kubectl get svc

# Verify Pod Logs
kubectl get pods
kubectl logs -f <USERMGMT-POD-NAME>
kubectl logs -f usermgmt-webapp-6ff7d7d849-7lrg5

Step-07: Verify Persistent Disks¶

Go to Compute Engine -> Storage -> Disks
Search for 4GB Persistent Disk
Observation: You should see the disk type as Balanced persistent disk

Step-08: Access Application¶

# List Services
kubectl get svc

# Access Application
http://<ExternalIP-from-get-service-output>
Username: admin101
Password: password101

# Create New User (Used for testing  `allowVolumeExpansion: true` Option)
Username: admin102
Password: password102
First Name: fname102
Last Name: lname102
Email Address: admin102@stacksimplify.com
Social Security Address: ssn102

Step-09: Update 01-persistent-volume-claim.yaml from 4Gi to 8Gi¶

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mysql-pv-claim
spec: 
  accessModes:
    - ReadWriteOnce
  storageClassName: gke-pd-standard-rwo-sc
  resources: 
    requests:
      #storage: 4Gi # Commment at Step-09
      storage: 8Gi # UnCommment at Step-09

Step-10: Deploy updated kube-manifests¶

# Deploy Kubernetes Manifests
kubectl apply -f kube-manifests/

# List PVC
kubectl get pvc
Observation:
1. Wait for 2 to 3 mins and automatically CAPACITY value changes from 4Gi to 8Gi

# List PV
kubectl get pv
Observation:
1. Wait for 2 to 3 mins and automatically CAPACITY value changes from 4Gi to 8Gi

# Access Application
http://<ExternalIP-from-get-service-output>
Username: admin101
Password: password101
Observation:
1. No impact to underlying MySQL Database data.
2. VolumeExpansion is seamless without impacting the real data. 
3. We should find the two users which are present before VolumeExpansion as-is.

Step-11: Verify Persistent Disks¶

Go to Compute Engine -> Storage -> Disks
Search for 8GB Persistent Disk, as 4GB disk expaned to 8GB now.
Observation: You should see the disk type as Balanced persistent disk

Step-12: Verify reclaimPolicy: Retain¶

# Delete kube-manifests
kubectl delete -f kube-manifests/

# List Storage Class
kubectl get sc
Observation:
1. Custom storage class deleted

# List PVC
kubectl get pvc
Observation:
1. PVC deleted

# List PV
kubectl get pv
Observation:
1. PV still present
2. PV STATUS will be in "Released", not used by anyoe.

Step-13: Verify Persistent Disks¶

Go to Compute Engine -> Storage -> Disks
Search for 8GB Persistent Disk.
Observation: You should see the disk is still present even after all kube-manifests (storageclass, pvc) all deleted.
This is due to we have used reclaimPolicy: Retain in Custom Storage Class

Step-14: Clone Persistent Disk¶

Question: Why we are cloning the disk ?
Answer: In the next demo, we are going use the pre-existing persistent disk in our demo. For that purpose we are cloning it.
Go to Compute Engine -> Storage -> Disks
Search for 8GB Persistent Disk.
Click on Clone Disk
Name: preexisting-pd
Description: preexisting-pd Demo with GKE
Location: Single
Snapshot Schedule: UNCHECK
Click on CREATE

Step-15: Delete Retained Persistent Disk from this Demo¶

Go to Compute Engine -> Storage -> Disks
Search for 8GB Persistent Disk.
Disk Name: pvc-3f2c1daa-122d-4bdb-a7b6-b9943631cc14

Click on DELETE DISK

# List PV
kubectl get pv

# Delete  PV 
kubectl delete pv pvc-3f2c1daa-122d-4bdb-a7b6-b9943631cc14 

# List PV
kubectl get pv

Step-16: Change PVC 8Gi to 4Gi: 01-persistent-volume-claim.yaml¶

Change PVC 8Gi to 4Gi so that kube-manifests will be demo ready for students.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mysql-pv-claim
spec: 
  accessModes:
    - ReadWriteOnce
  storageClassName: gke-pd-standard-rwo-sc
  resources: 
    requests:
      storage: 4Gi # Commment at Step-09
      #storage: 8Gi # UnCommment at Step-09

Reference¶

Using the Compute Engine persistent disk CSI Driver