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Kubernetes Volumes: Nginx Pod and Deployment Examples with NFS Volume, Pod and Deployment Examples with EmptyDir Volume, Deployment Example with PersistentVolume, External Storage Provider with NFS

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Kubernetes Kubectl
Table of Contents
Kubernetes-Components - This article is part of a series.
Part 1: Kubernetes Configuration Manifests: Create Manifests from RAW Output and Dry-Run Command
Part 2: Kubernetes Non-Disruptive & Disruptive Configuration Updates: Kubectl Apply, Edit, Patch & Replace; Update Rollouts and Rollbacks with Set Image Command
Part 3: Kubernetes Pods: Create Pods with Run-Command and YAML Configuration; Single & Multi Container Pods, Port-Forwarding, Find Container on Worker Node
Part 4: Kubernetes Pods: Init & Sidecar Container Overview, Init Container Examples
Part 5: Kubernetes Kubernetes Deployments & Replication Controllers (Soon Depricated): Example Deployment with Create-Command and YAML Configuration, Scale the Deployment; Example Replication Controller
Part 6: Kubernetes Services: Example ClusterIP, NodePort & LoadBalancer Services with Expose-Command and YAML Configuration; Service for External Endpoint
Part 7: Kubernetes Resource Management: Deploy Kubernetes Metrics Server, Vish/Stress Container Example, Define Resource Requests and Limits, Verify Resource Usage with kubectl top, Define a LimitRange for a Namespace
Part 8: Kubernetes Monitoring & Logs: Monitor Applications with top, Monitor Events Pod specific and Cluster wide, Container STDOUT and STDERR Logs
Part 9: Kubernetes Security: Immutable Deployment - Deploy Container with ReadOnly-Filesystem and Writable-Volume
Part 10: Kubernetes Security: Pod Security Admission (PSA) - Overview, Enforce Pod Security Standard at a Namespace; Example Nginx Pod SecurityContext for Restricted PSS
Part 11: This Article
Part 12: Kubernetes Secrets: Opaque Secret Configuration, Pod Examples with Environment Variable Secrets and Volume Secrets; SSH Authentication Secret with Pod Example
Part 13: Kubernetes ConfigMaps: Mount ConfigMap to Pod as Volume, Mount ConfigMap as Environment Variable
Part 14: Kubernetes Sets - ReplicaSets & DaemonSets: Overview, Example ReplicaSet, Example DaemonSet with and without NodeSelector / Node Labeling
Part 15: Kubernetes Sets - StatefulSets: Difference between StatefulSet & ReplcaSet; StatefulSet Example with VolumeClaimTemplate and Stateless Service
Part 16: Kubernetes Labels, Annotations, Affinity / Anti-Affinity, Taints & Tolerations: Node Labeling, Pod Labeling & NodeSelector; Pod Annotations; Node Affinity, Pod Anti-Affinity; Node Taints and Pod Tolerations
Part 17: Kubernetes Configuration Management - Helm Charts: Create a Custom Helm Chart
Part 18: Kubernetes Configuration Management - Kustomize: Kustomize Example
Part 19: Kubernetes Networking - Network Policies: Ingress and Egress Policy Examples
Part 20: Kubernetes Networking - Liveness, Readiness & Startup Probe Examples: Liveness Probe (TCP), Readiness Probes (TCP / Single Pod and Multi Pod Dependency), Startup Probe (Command, TCP & HTTP)
Part 21: Kubernetes Networking - DNS: CoreDNS custom Hosts entry (K3s & K8s Version), Deployment with custom Hosts entry; Backup and Restore the CoreDNS ConfigMap; DNS Troubleshooting
Part 22: Kubernetes Horizontal Pod Autoscaling: Install Kubernetes Metrics Server, Example Deployment with Horizontal Pod Autoscaler (HPA)
Part 23: Kubernetes Jobs: Jobs Overview, Basic Non-parallel & Parallel Job Examples; CronJob & RBAC Example that Restarts a Deployment
Part 24: Kubernetes Role Based Access Control (RBAC): RBAC Overview, Create Service Account, Example Role and RoleBinding
Part 25: Kubernetes Kubeconfig: Create example Kubeconfig with new (RBAC) Service Account and ClusterRole / ClusterRole Binding
Part 26: Kubernetes Etcd Snapshot: Etcd Snapshot and Restore with Etcdctl, Verify Etcd Member Health; Etcdctl Commands
Part 27: Kubernetes Troubleshooting: Cluster, Nodes, Pods & Kubelet
Part 28: Kubernetes Commands: Kubectl Autocomplete, Cluster Nodes, Namespaces, LimitRange Resource Limits, Pods, Deployments, Replication Controllers, Services, HPA, Secrets, Cronjobs, Helm, Logs, K9s TUI

Overview
#

I use the following nodes based on a Kubernetes K8s cluster with MetalLB, that is deployed bare metal on Debian 12 in this tutorial:

192.168.30.71 deb-02 # Controller / Master Node
192.168.30.72 deb-03 # Controller / Master Node
192.168.30.73 deb-04 # Worker Node
192.168.30.74 deb-05 # Worker Node
192.168.30.60 # NFS server

Kubernetes Volumes Types
#

  • nfs Multiple pods can mount and share the files in the same nfs volume. If the pod is terminated, the data is still accessible on the NFS share.

  • emptyDir Creates an volume for containers in the same pod to share. The volume and it’s files is erased when the pod is removed.


Nginx with NFS Volume Example
#

NFS Server Setup
#

I’m using the following NFS server configuration:

# Install NFS package
sudo apt install nfs-kernel-server

# Open NFS configuration
sudo vi /etc/exports

# NFS configuration
/srv/nfs/k8s_share 192.168.30.71(rw,sync,no_root_squash)
/srv/nfs/k8s_share 192.168.30.72(rw,sync,no_root_squash)
/srv/nfs/k8s_share 192.168.30.73(rw,sync,no_root_squash)
/srv/nfs/k8s_share 192.168.30.74(rw,sync,no_root_squash)

# Install NFS package
sudo apt install nfs-kernel-server

# Restart NFS server
sudo systemctl restart nfs-server

Install NFS on Kubernetes Nodes
#

Install the NFS utilities package on all Kubernetes nodes:

# Install NFS utilities package
sudo apt install nfs-common -y

Verify the NFS Server Configuration
#

Verify the connection to the NFS server from all Kubernetes nodes:

# Install NFS utilities package (Should already be installed)
sudo apt install nfs-common -y

# Find the showmount bin
find / -name showmount 2>/dev/null

# Verify that the NFS server is correctly configured
/usr/sbin/showmount -e 192.168.30.60

# Shell output:
Export list for 192.168.30.60:
/srv/nfs/k8s_share 192.168.30.74,192.168.30.73,192.168.30.72,192.168.30.71

Optional: Manually mount the NFS server on the Kubernetes nodes, to verify that it workes:

# Mount NFS share
sudo mount -t nfs 192.168.30.60:/srv/nfs/k8s_share /mnt

# Verify mount
ls /mnt

# Shell output:
index.html

# Unmount
sudo umount /mnt

Nginx Pod with NFS Mount
#

Pod Configuration
# 

# Create configuration for the pod
vi nginx-nfs-pod.yaml

apiVersion: v1
kind: Pod
metadata:
  name: nfs-nginx
  labels:
    app: nfs-nginx
spec:
  containers:
  - name: nginx-container
    image: nginx
    volumeMounts:
      - name: nfs
        mountPath: "/usr/share/nginx/html"  # Mount to the Nginx web root
    ports:
    - containerPort: 80
  volumes:
    - name: nfs
      nfs:
        server: "192.168.30.60"
        path: "/srv/nfs/k8s_share"

# Deploy the pod
kubectl create -f nginx-nfs-pod.yaml

Pod Details & Logs
# 

# List pod details: Check the NFS mounting status
kubectl describe pod nfs-nginx

# Shell output:
Name:             nfs-nginx
Namespace:        default
Priority:         0
Service Account:  default
Node:             node4/192.168.30.74
Start Time:       Tue, 28 May 2024 19:37:02 +0200
Labels:           app=nfs-nginx
Annotations:      cni.projectcalico.org/containerID: 52ab9edd6534cc409bed8ecf4ad5210b46aa42e34a1dd48e98817a39c3b0a629
                  cni.projectcalico.org/podIP: 10.233.74.92/32
                  cni.projectcalico.org/podIPs: 10.233.74.92/32
Status:           Running
IP:               10.233.74.92
IPs:
  IP:  10.233.74.92
...
...
Events:
  Type    Reason     Age   From               Message
  ----    ------     ----  ----               -------
  Normal  Scheduled  5s    default-scheduler  Successfully assigned default/nfs-nginx to node4
  Normal  Pulling    5s    kubelet            Pulling image "nginx"
  Normal  Pulled     4s    kubelet            Successfully pulled image "nginx" in 1.011s (1.011s including waiting)
  Normal  Created    4s    kubelet            Created container nginx-container
  Normal  Started    3s    kubelet            Started container nginx-container

# List the pods logs:
kubectl logs nfs-nginx

Verify the Nginx Website
# 

# Curl the Nginx website
curl 10.233.74.92:80

Delete the Resources
# 

# Delete the pod
kubectl delete pod nfs-nginx

Nginx Deployment with NFS Mount
#

Deployment Configuration
# 

# Create configuration for the deployment
vi nginx-nfs-deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nfs-nginx-deployment
  labels:
    app: nfs-nginx
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nfs-nginx  # Labels of the pods being selected
  template:
    metadata:
      labels:
        app: nfs-nginx  # Labels applied to the pods created from this template
    spec:
      containers:
      - name: nginx-container
        image: nginx
        ports:
        - containerPort: 80
        volumeMounts:
        - name: nfs
          mountPath: "/usr/share/nginx/html"  # Mount to the Nginx web root
      volumes:
      - name: nfs
        nfs:
          server: "192.168.30.60"
          path: "/srv/nfs/k8s_share"

# Deploy the pod
kubectl create -f nginx-nfs-deployment.yaml

Verify the Deployment
# 

# Verify the pods are deployed
kubectl get deployments nfs-nginx-deployment

# Shell output:
NAME                   READY   UP-TO-DATE   AVAILABLE   AGE
nfs-nginx-deployment   2/2     2            2           20s

List Deployment Details
# 

# List the deployment details
kubectl describe deployment nfs-nginx-deployment

# Shell output:
Pod Template:
  Labels:  app=nfs-nginx
  Containers:
   nginx-container:
    Image:        nginx
    Port:         80/TCP
    Host Port:    0/TCP
    Environment:  <none>
    Mounts:
      /usr/share/nginx/html from nfs (rw)
  Volumes:
   nfs:
    Type:      NFS (an NFS mount that lasts the lifetime of a pod)
    Server:    192.168.30.60
    Path:      /srv/nfs/k8s_share
    ReadOnly:  false
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      True    MinimumReplicasAvailable
  Progressing    True    NewReplicaSetAvailable
OldReplicaSets:  <none>
NewReplicaSet:   nfs-nginx-deployment-cf964486f (2/2 replicas created)
Events:
  Type    Reason             Age    From                   Message
  ----    ------             ----   ----                   -------
  Normal  ScalingReplicaSet  3m10s  deployment-controller  Scaled up replica set nfs-nginx-deployment-cf964486f to 2

Create a LoadBalancer Service
# 

vi nfs-nginx-loadbalancer.yaml

apiVersion: v1
kind: Service
metadata:
  name: nfs-nginx-loadbalancer
spec:
  type: LoadBalancer
  selector:
    app: nfs-nginx # This must match the label selector of the deployment
  ports:
    - protocol: TCP
      port: 80  # The port the LoadBalancer service will be accessible on
      targetPort: 80  # The container port to direct traffic to

# Deploy the LoadBalancer service
kubectl apply -f nfs-nginx-loadbalancer.yaml

LoadBalancer Service Details
# 

# List LoadBalancer service details
kubectl get svc nfs-nginx-loadbalancer

# Shell output:
NAME                     TYPE           CLUSTER-IP      EXTERNAL-IP      PORT(S)        AGE
nfs-nginx-loadbalancer   LoadBalancer   10.233.23.246   192.168.30.242   80:30389/TCP   32s

Access the LoadBalancer
# 

# Open the URL in a browser
192.168.30.242:80

Delete Resources
# 

# Delete the LoadBalancer service
kubectl delete svc nfs-nginx-loadbalancer

# Delete the deployment
delete deployment nfs-nginx-deployment

EmptyDir Volume Example
#

This is a simple example of two containers in a pod using a shared emptyDir volume in the pod. The frist alpine container writes a html file into the volume, the second Nginx container deployes the file as a website.

Two Container Pod with EmptyDir Volume
#

Pod Configuration
# 

# Create configuration for the pod
vi emptydir-shared-storage-pod.yaml

apiVersion: v1
kind: Pod
metadata:
  name: emptydir-shared-storage
  labels:
    app: nfs-nginx
spec:
  containers:

    - name: alpine-container
      image: alpine
      volumeMounts:
        - name: shared-storage
          mountPath: /usr/share/data
      command: ["/bin/sh"]
      args: ["-c", "echo 'EmptyDir Volume Example' > /usr/share/data/index.html; sleep infinity"]

    - name: nginx-container
      image: nginx
      volumeMounts:
        - name: shared-storage
          mountPath: "/usr/share/nginx/html"
      ports:
      - containerPort: 80

  volumes:
    - name: shared-storage
      emptyDir: {}

# Deploy the pod
kubectl create -f emptydir-shared-storage-pod.yaml

Pod Details & Logs
# 

# List pods
kubectl get pods

# Shell output:
NAME                      READY   STATUS    RESTARTS   AGE
emptydir-shared-storage   2/2     Running   0          7s

# List pod details: 
kubectl describe pod emptydir-shared-storage

# Shell output:
Name:             emptydir-shared-storage
Namespace:        default
Priority:         0
Service Account:  default
Node:             node4/192.168.30.74
Start Time:       Tue, 28 May 2024 22:55:16 +0200
Labels:           app=nfs-nginx
Annotations:      cni.projectcalico.org/containerID: 2cb0c5f2f828a260b8a85128e87b6831a1958bd7f06fa46e9f67643c8768e220
                  cni.projectcalico.org/podIP: 10.233.74.98/32
                  cni.projectcalico.org/podIPs: 10.233.74.98/32
Status:           Running
IP:               10.233.74.98
IPs:
  IP:  10.233.74.98
...
...
Events:
  Type    Reason     Age   From               Message
  ----    ------     ----  ----               -------
  Normal  Scheduled  22s   default-scheduler  Successfully assigned default/emptydir-shared-storage to node4
  Normal  Pulling    21s   kubelet            Pulling image "alpine"
  Normal  Pulled     20s   kubelet            Successfully pulled image "alpine" in 1.008s (1.008s including waiting)
  Normal  Created    20s   kubelet            Created container alpine-container
  Normal  Started    20s   kubelet            Started container alpine-container
  Normal  Pulling    20s   kubelet            Pulling image "nginx"
  Normal  Pulled     19s   kubelet            Successfully pulled image "nginx" in 967ms (967ms including waiting)
  Normal  Created    19s   kubelet            Created container nginx-container
  Normal  Started    19s   kubelet            Started container nginx-container

# List the pods logs:
kubectl logs emptydir-shared-storage

Verify the Nginx Website
# 

# Curl the Nginx website
curl 10.233.74.98:80

# Shell output:
EmptyDir Volume Example

Delete the Resources
# 

# Delete the pod
kubectl delete pod emptydir-shared-storage

Two Container Deployment with EmptyDir Volume
#

Deployment Configuration
# 

# Create configuration for the deployment
vi emptydir-shared-storage-deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: emptydir-shared-storage-deployment
  labels:
    app: emptydir-nginx
spec:
  replicas: 2
  selector:
    matchLabels:
      app: emptydir-nginx  # Labels of the pods being selected
  template:
    metadata:
      labels:
        app: emptydir-nginx  # Labels applied to the pods created from this template
    spec:
      containers:
        - name: alpine-container
          image: alpine
          volumeMounts:
            - name: shared-storage
              mountPath: /usr/share/data
          command: ["/bin/sh"]
          args: ["-c", "echo 'EmptyDir Volume Example' > /usr/share/data/index.html; sleep infinity"]

        - name: nginx-container
          image: nginx
          volumeMounts:
            - name: shared-storage
              mountPath: "/usr/share/nginx/html"
          ports:
            - containerPort: 80

      volumes:
        - name: shared-storage
          emptyDir: {}

# Deploy the pod
kubectl create -f emptydir-shared-storage-deployment.yaml

Verify the Deployment
# 

# List the pods of the deployment
kubectl get pods -l app=emptydir-nginx

# Shell output:
NAME                                                  READY   STATUS    RESTARTS   AGE
emptydir-shared-storage-deployment-76f857754f-5fjwk   2/2     Running   0          3m45s
emptydir-shared-storage-deployment-76f857754f-pghcv   2/2     Running   0          3m45

# Verify the pods are deployed
kubectl get deployments emptydir-shared-storage-deployment

# Shell output:
NAME                                 READY   UP-TO-DATE   AVAILABLE   AGE
emptydir-shared-storage-deployment   2/2     2            2           4m52s

List Deployment Details
# 

# List the deployment details
kubectl describe deployment emptydir-shared-storage-deployment

# Shell output:
Events:
  Type    Reason             Age   From                   Message
  ----    ------             ----  ----                   -------
  Normal  ScalingReplicaSet  37s   deployment-controller  Scaled up replica set emptydir-shared-storage-deployment-76f857754f to 2

Create a LoadBalancer Service
# 

vi emptydir-shared-storage-loadbalancer.yaml

apiVersion: v1
kind: Service
metadata:
  name: emptydir-shared-storage-loadbalancer
spec:
  type: LoadBalancer
  selector:
    app: emptydir-nginx # This must match the label selector of the deployment
  ports:
    - protocol: TCP
      port: 80  # The port the LoadBalancer service will be accessible on
      targetPort: 80  # The container port to direct traffic to

# Deploy the LoadBalancer service
kubectl apply -f emptydir-shared-storage-loadbalancer.yaml

LoadBalancer Service Details
# 

# List LoadBalancer service details
kubectl get svc emptydir-shared-storage-loadbalancer

# Shell output:
NAME                                   TYPE           CLUSTER-IP      EXTERNAL-IP      PORT(S)        AGE
emptydir-shared-storage-loadbalancer   LoadBalancer   10.233.25.241   192.168.30.241   80:30931/TCP   6s

Access the LoadBalancer
# 

# Open the URL in a browser
192.168.30.241:80

# Or use curl
curl 192.168.30.241:80

# Shell output

Delete Resources
# 

# Delete the LoadBalancer service
kubectl delete svc emptydir-shared-storage-loadbalancer

# Delete the deployment
kubectl delete deployment emptydir-shared-storage-deployment

PersistentVolume Example
#

Overview
#

  1. Provision the specification of a PersistentVolume (PV)

  2. Request for storage by PersistentVolumeClaim (PVC). PVCs can request specific size and access modes (such as read/write or read-only).

  3. A pod mounts the volume by the reference of the PersistentVolumeClaim (PVC)

PersistentVolume (PV)
#

Host Path & HTML File
#

Create the host path on a specific worker node, or all worker nodes, regarding the PersistentVolume configuration that is used:

# Create the host path
sudo mkdir -p /mnt/example-dir

# Create a index.html file for Nginx
echo "PersistentVolume Example" | sudo tee /mnt/example-dir/index.html

YAML Configuration
# 

# Create the PersistentVolume configuration
vi persistentvolume-example.yaml
PersistentVolume: General host path 
apiVersion: v1
kind: PersistentVolume
metadata:
  name: example-pv
spec:
  capacity:
    storage: 3Gi
  volumeMode: Filesystem
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Retain
  storageClassName: manual
  hostPath:
    path: /mnt/example-dir
PersistentVolume: Specified node host path 
apiVersion: v1
kind: PersistentVolume
metadata:
  name: example-pv
spec:
  capacity:
    storage: 3Gi
  volumeMode: Filesystem
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Retain
  storageClassName: manual
  hostPath:
    path: /mnt/example-dir
  nodeAffinity:
    required:
      nodeSelectorTerms:
      - matchExpressions:
        - key: kubernetes.io/hostname
          operator: In
          values:
          - node3

Note: This setup ties the scheduling of any pod that uses this PV to Kubernetes node3.

# Create the PersistentVolume
kubectl create -f persistentvolume-example.yaml

Description
#

AccessModes: (Based on the capability of the storage provider)

  • ReadWriteOnce Allows the volume to be mounted as read-write by a single node. This means only one node can mount the volume and read from or write to it at any one time. (Commonly used for databases)

  • ReadOnlyMany Storage provider must support multiple readers and writers simultaneously

  • ReadWriteMany Storage provider must support multiple readers and writers simultaneously

persistentVolumeReclaimPolicy:

  • Retain Volume persists when the PVC is deleted
  • Recycle Kubernetes will delete the volume

List PersistentVolumes & Details
# 

# List PersistentVolumes
kubectl get pv

# Shell output:
NAME         CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM   STORAGECLASS   VOLUMEATTRIBUTESCLASS   REASON   AGE
example-pv   3Gi        RWO            Retain           Available           manual         <unset>                          11s

# List PV details
kubectl describe pv example-pv

# Shell:
Name:              example-pv
Labels:            <none>
Annotations:       <none>
Finalizers:        [kubernetes.io/pv-protection]
StorageClass:      manual
Status:            Available
Claim:
Reclaim Policy:    Retain
Access Modes:      RWO
VolumeMode:        Filesystem
Capacity:          3Gi
Node Affinity:
  Required Terms:
    Term 0:        kubernetes.io/hostname in [node3]
Message:
Source:
    Type:          HostPath (bare host directory volume)
    Path:          /mnt/example-dir
    HostPathType:
Events:            <none>

PersistentVolumeClaim (PVC)
# 

# Create a PersistentVolumeClaim configuration
vi persistentvolume-claim-example.yaml

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: example-pvc
spec:
  accessModes:
    - ReadWriteOnce
  volumeMode: Filesystem
  resources:
    requests:
      storage: 1Gi
  storageClassName: manual

# Create the PersistentVolumeClaim
kubectl create -f persistentvolume-claim-example.yaml

List PersistentVolumeClaims & Details
# 

# List PersistentVolumeClaims
kubectl get pvc

# Shell output:
NAME          STATUS   VOLUME       CAPACITY   ACCESS MODES   STORAGECLASS   VOLUMEATTRIBUTESCLASS   AGE
example-pvc   Bound    example-pv   3Gi        RWO            manual         <unset>                 4s

STATUS:

  • Bound Claim is bound successfully
  • Unbound No PersistentVolume matches the request
# List PV details
kubectl describe pvc example-pvc

# Shell:
Name:          example-pvc
Namespace:     default
StorageClass:  manual
Status:        Bound
Volume:        example-pv
Labels:        <none>
Annotations:   pv.kubernetes.io/bind-completed: yes
               pv.kubernetes.io/bound-by-controller: yes
Finalizers:    [kubernetes.io/pvc-protection]
Capacity:      3Gi
Access Modes:  RWO
VolumeMode:    Filesystem
Used By:       <none>
Events:        <none>

Deployment with PVC Volume
# 

# Create deployment configuration
vi pvc-nginx-deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: pvc-nginx-deployment
  labels:
    app: pvc-nginx
spec:
  replicas: 1
  selector:
    matchLabels:
      app: pvc-nginx  # Labels of the pods being selected
  template:
    metadata:
      labels:
        app: pvc-nginx # Labels applied to the pods created from this template
    spec:
      containers:
      - name: nginx-container
        image: nginx
        ports:
        - containerPort: 80
        volumeMounts:
        - name: example-pvc-volume
          mountPath: "/usr/share/nginx/html"  # Mount to the Nginx web root
      volumes:
      - name: example-pvc-volume
        persistentVolumeClaim:
          claimName: example-pvc

# Deploy the pod
kubectl create -f pvc-nginx-deployment.yaml

List Deployment Details
# 

# List deployment details
kubectl describe deployment pvc-nginx-deployment

# Shell putput:
Name:                   pvc-nginx-deployment
Namespace:              default
CreationTimestamp:      Wed, 29 May 2024 23:32:24 +0200
Labels:                 app=pvc-nginx
Annotations:            deployment.kubernetes.io/revision: 1
Selector:               app=pvc-nginx
Replicas:               1 desired | 1 updated | 1 total | 1 available | 0 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:  app=pvc-nginx
  Containers:
   nginx-container:
    Image:        nginx
    Port:         80/TCP
    Host Port:    0/TCP
    Environment:  <none>
    Mounts:
      /usr/share/nginx/html from example-pvc-volume (rw)
  Volumes:
   example-pvc-volume:
    Type:       PersistentVolumeClaim (a reference to a PersistentVolumeClaim in the same namespace)
    ClaimName:  example-pvc
    ReadOnly:   false
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      True    MinimumReplicasAvailable
  Progressing    True    NewReplicaSetAvailable
OldReplicaSets:  <none>
NewReplicaSet:   pvc-nginx-deployment-6f5d749f7f (1/1 replicas created)
Events:
  Type    Reason             Age    From                   Message
  ----    ------             ----   ----                   -------
  Normal  ScalingReplicaSet  2m36s  deployment-controller  Scaled up replica set pvc-nginx-deployment-6f5d749f7f to 1

Create a LoadBalancer Service
# 

# Create the LoadBalancer configuration
vi pvc-nginx-deployment-loadbalancer.yaml

apiVersion: v1
kind: Service
metadata:
  name: pvc-nginx-deployment-loadbalancer
spec:
  type: LoadBalancer
  selector:
    app: pvc-nginx # This must match the label selector of the deployment
  ports:
    - protocol: TCP
      port: 80  # The port the LoadBalancer service will be accessible on
      targetPort: 80  # The container port to direct traffic to

# Deploy the LoadBalancer service
kubectl apply -f pvc-nginx-deployment-loadbalancer.yaml

LoadBalancer Service Details
# 

# List LoadBalancer service details
kubectl get svc pvc-nginx-deployment-loadbalancer

# Shell output:
NAME                                TYPE           CLUSTER-IP      EXTERNAL-IP      PORT(S)        AGE
pvc-nginx-deployment-loadbalancer   LoadBalancer   10.233.56.172   192.168.30.241   80:31292/TCP   4s

Access the LoadBalancer
# 

# Open the URL in a browser
192.168.30.241:80

# Or use curl
curl 192.168.30.241:80

Delete Resources
# 

# Delete the LoadBalancer service
kubectl delete svc pvc-nginx-deployment-loadbalancer

# Delete the deployment
kubectl delete deployment pvc-nginx-deployment

# Delete the PVC
kubectl delete pvc example-pvc

# Delete the PV
kubectl delete pv example-pv



External Storage Provider
#

Helm
#

Helm Repository: NFS Subdir External Provisioner
# 

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

Deploy the Provisioner
#

Install the NFS provisioner in the “kube-system” namespace and configures it to use the NFS server:

# Update package index
helm install nfs-provisioner nfs-subdir-external-provisioner/nfs-subdir-external-provisioner \
    --set nfs.server=192.168.30.60 \
    --set nfs.path=/srv/nfs/k8s_share \
    --namespace kube-system

# Shell output:
NAME: nfs-provisioner
LAST DEPLOYED: Sat Jun 15 16:08:06 2024
NAMESPACE: kube-system
STATUS: deployed
REVISION: 1
TEST SUITE: None

Verify the StorageClass
# 

# List storage classes
kubectl get storageclass

# Shell output:
NAME             PROVISIONER                                                     RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE
local-storage    kubernetes.io/no-provisioner                                    Delete          Immediate           false                  44h
nfs-client       cluster.local/nfs-provisioner-nfs-subdir-external-provisioner   Delete          Immediate           true                   24s

# List storage class details
kubectl describe sc nfs-client

# Shell output:
Name:                  nfs-client
IsDefaultClass:        No
Annotations:           meta.helm.sh/release-name=nfs-provisioner,meta.helm.sh/release-namespace=kube-system
Provisioner:           cluster.local/nfs-provisioner-nfs-subdir-external-provisioner
Parameters:            archiveOnDelete=true
AllowVolumeExpansion:  True
MountOptions:          <none>
ReclaimPolicy:         Delete
VolumeBindingMode:     Immediate
Events:                <none>

Configure Default StorageClass
# 

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

Verify the “IsDefaultClass” is set to “Yes”:

# Verify / list storage class details
kubectl describe storageclass nfs-client

# Shell output:
Name:                  nfs-client
IsDefaultClass:        Yes
Annotations:           meta.helm.sh/release-name=nfs-provisioner,meta.helm.sh/release-namespace=kube-system,storageclass.kubernetes.io/is-default-class=true
Provisioner:           cluster.local/nfs-provisioner-nfs-subdir-external-provisioner
Parameters:            archiveOnDelete=true
AllowVolumeExpansion:  True
MountOptions:          <none>
ReclaimPolicy:         Delete
VolumeBindingMode:     Immediate
Events:                <none>

PersistentVolumeClaim Test
#

Test if a PersistentVolumeClaim is able to bind:

PersistentVolumeClaim Manifest
# 

# Create a manifest for the test PVC
vi nfs-test-pvc.yaml

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

# Deploy the PVS
kubectl apply -f nfs-test-pvc.yaml

Verify the PVC Bind
# 

# Verify the binding of the PVC
kubectl get pvc test-nfs-pvc

# Shell output:
NAME           STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   VOLUMEATTRIBUTESCLASS   AGE
nfs-test-pvc   Bound    pvc-cd8b737a-155d-4ef0-aac7-c80f15334296   1Gi        RWX            nfs-client     <unset>                 4s

Delete the PVC Test
# 

# Delete the PVC
kubectl delete pvc nfs-test-pvc
Kubernetes-Components - This article is part of a series.
Part 1: Kubernetes Configuration Manifests: Create Manifests from RAW Output and Dry-Run Command
Part 2: Kubernetes Non-Disruptive & Disruptive Configuration Updates: Kubectl Apply, Edit, Patch & Replace; Update Rollouts and Rollbacks with Set Image Command
Part 3: Kubernetes Pods: Create Pods with Run-Command and YAML Configuration; Single & Multi Container Pods, Port-Forwarding, Find Container on Worker Node
Part 4: Kubernetes Pods: Init & Sidecar Container Overview, Init Container Examples
Part 5: Kubernetes Kubernetes Deployments & Replication Controllers (Soon Depricated): Example Deployment with Create-Command and YAML Configuration, Scale the Deployment; Example Replication Controller
Part 6: Kubernetes Services: Example ClusterIP, NodePort & LoadBalancer Services with Expose-Command and YAML Configuration; Service for External Endpoint
Part 7: Kubernetes Resource Management: Deploy Kubernetes Metrics Server, Vish/Stress Container Example, Define Resource Requests and Limits, Verify Resource Usage with kubectl top, Define a LimitRange for a Namespace
Part 8: Kubernetes Monitoring & Logs: Monitor Applications with top, Monitor Events Pod specific and Cluster wide, Container STDOUT and STDERR Logs
Part 9: Kubernetes Security: Immutable Deployment - Deploy Container with ReadOnly-Filesystem and Writable-Volume
Part 10: Kubernetes Security: Pod Security Admission (PSA) - Overview, Enforce Pod Security Standard at a Namespace; Example Nginx Pod SecurityContext for Restricted PSS
Part 11: This Article
Part 12: Kubernetes Secrets: Opaque Secret Configuration, Pod Examples with Environment Variable Secrets and Volume Secrets; SSH Authentication Secret with Pod Example
Part 13: Kubernetes ConfigMaps: Mount ConfigMap to Pod as Volume, Mount ConfigMap as Environment Variable
Part 14: Kubernetes Sets - ReplicaSets & DaemonSets: Overview, Example ReplicaSet, Example DaemonSet with and without NodeSelector / Node Labeling
Part 15: Kubernetes Sets - StatefulSets: Difference between StatefulSet & ReplcaSet; StatefulSet Example with VolumeClaimTemplate and Stateless Service
Part 16: Kubernetes Labels, Annotations, Affinity / Anti-Affinity, Taints & Tolerations: Node Labeling, Pod Labeling & NodeSelector; Pod Annotations; Node Affinity, Pod Anti-Affinity; Node Taints and Pod Tolerations
Part 17: Kubernetes Configuration Management - Helm Charts: Create a Custom Helm Chart
Part 18: Kubernetes Configuration Management - Kustomize: Kustomize Example
Part 19: Kubernetes Networking - Network Policies: Ingress and Egress Policy Examples
Part 20: Kubernetes Networking - Liveness, Readiness & Startup Probe Examples: Liveness Probe (TCP), Readiness Probes (TCP / Single Pod and Multi Pod Dependency), Startup Probe (Command, TCP & HTTP)
Part 21: Kubernetes Networking - DNS: CoreDNS custom Hosts entry (K3s & K8s Version), Deployment with custom Hosts entry; Backup and Restore the CoreDNS ConfigMap; DNS Troubleshooting
Part 22: Kubernetes Horizontal Pod Autoscaling: Install Kubernetes Metrics Server, Example Deployment with Horizontal Pod Autoscaler (HPA)
Part 23: Kubernetes Jobs: Jobs Overview, Basic Non-parallel & Parallel Job Examples; CronJob & RBAC Example that Restarts a Deployment
Part 24: Kubernetes Role Based Access Control (RBAC): RBAC Overview, Create Service Account, Example Role and RoleBinding
Part 25: Kubernetes Kubeconfig: Create example Kubeconfig with new (RBAC) Service Account and ClusterRole / ClusterRole Binding
Part 26: Kubernetes Etcd Snapshot: Etcd Snapshot and Restore with Etcdctl, Verify Etcd Member Health; Etcdctl Commands
Part 27: Kubernetes Troubleshooting: Cluster, Nodes, Pods & Kubelet
Part 28: Kubernetes Commands: Kubectl Autocomplete, Cluster Nodes, Namespaces, LimitRange Resource Limits, Pods, Deployments, Replication Controllers, Services, HPA, Secrets, Cronjobs, Helm, Logs, K9s TUI