LAB11c: Dynamic Storage Provisioning

LAB80 Dynamic Storage Provisioning

Setup NFS

1. Create the shared directory:

sudo mkdir -p /srv/nfs_share

1. Set permissions

sudo chown nobody:nogroup /srv/nfs_share
sudo chmod 777 /srv/nfs_share

1. Start NFS server

# Use --network=host and omit the -p port mappings
docker run -d \
  --name nfs-server \
  --privileged \
  --restart unless-stopped \
  --network=host \
  -v /srv/nfs_share:/data:rw \
  -e SHARED_DIRECTORY=/data \
  -e PERMITTED_CLIENTS="*" \
  itsthenetwork/nfs-server-alpine:12

Check logs

docker logs nfs-server

1. Install NFS client packages on every node

sudo apt update && sudo apt install nfs-common

To test mounting the share

sudo mkdir -p /mnt/test_nfs4
sudo mount -t nfs4 -o proto=tcp,port=2049 ><nfs_server_ip>:/ /mnt/test_nfs4

---

1. Add the official Helm repo

helm repo add nfs-subdir-external-provisioner https://kubernetes-sigs.github.io/nfs-subdir-external-provisioner/
helm repo update

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2. Create namespace

kubectl create namespace nfs-provisioner

---

3. Install using Helm (correct full command)

helm install nfs-provisioner \
  nfs-subdir-external-provisioner/nfs-subdir-external-provisioner \
  --namespace nfs-provisioner \
  --set nfs.server=<nfs_server_IP> \
  --set nfs.path=<nfs_share> \
  --set storageClass.name=nfs-client \
  --set storageClass.create=true \
  --set storageClass.defaultClass=false \
  --set storageClass.onDelete=true

What each flag does:

Flag	Meaning
--set nfs.server=	NFS server IP address
--set nfs.path=	Path exported by your NFS server
--set storageClass.create=true	Automatically create a StorageClass
--set storageClass.name=nfs-client	Name the SC nfs-client
--set storageClass.onDelete=true	Cleanup subdir when PVC deleted
--namespace nfs-provisioner	Clean isolation

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4. Verify installation

Pod:

kubectl get pods -n nfs-provisioner

Should show:

nfs-provisioner-xxxxx   1/1   Running

StorageClass:

kubectl get sc

Should show:

nfs-client   k8s-sigs.io/nfs-subdir-external-provisioner

---

5. Test with a PVC

Create pvc.yaml:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: test-pvc
spec:
  storageClassName: nfs-client
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 1Gi

Apply:

kubectl apply -f pvc.yaml
kubectl get pvc

Expected:

STATUS: Bound

---

6. Verify NFS directory creation

On your NFS server:

ls -l /data/nfs

You will see:

default-test-pvc-xxxxx/

📌 That means dynamic provisioning works.

---

Bonus: Make it the default StorageClass

If you want this to be the default SC:

kubectl patch storageclass nfs-client -p '{"metadata": {"annotations":{"storageclass.kubernetes.io/is-default-class":"true"}}}'

Test - Filling up Storage Quota

---

storage-filler.yaml

apiVersion: v1
kind: Pod
metadata:
  name: storage-filler
spec:
  containers:
    - name: filler
      image: busybox
      command: ["/bin/sh", "-c"]
      args:
        - |
          echo "Starting slow storage fill..."
          i=1
          while true; do
            echo "Creating file $i..."
            dd if=/dev/urandom of=/data/file_$i.bin bs=100M count=1 2>&1
            if [ $? -ne 0 ]; then
              echo "❌ Write failed — storage is FULL!"
              break
            fi
            i=$((i+1))
            sleep 5
          done
          echo "Sleeping so pod stays alive..."
          sleep 3600;
      volumeMounts:
        - name: vol
          mountPath: /data
  volumes:
    - name: vol
      persistentVolumeClaim:
        claimName: your-pvc-name

Replace:

your-pvc-name

with your real PVC name (the one that is 1 GB).

---

How to Run This

Apply PVC (example 1 GB)

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: test-pvc
spec:
  storageClassName: nfs-client
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 1Gi

Apply:

kubectl apply -f pvc.yaml
kubectl apply -f storage-filler.yaml

---

What You Will Observe When PVC Becomes Full

Your cluster will begin telling tales:

1. dd write error

Inside container logs:

dd: writing 'file_11.bin': No space left on device
❌ Write failed — storage is FULL!

2. Events on Pod

kubectl describe pod storage-filler

You may see:

No space left on device
Failed to write
Input/output error