Kubernetes Storage

Overview

This guide covers storage concepts in Kubernetes, including volumes, persistent volumes, storage classes, and best practices for managing application data.

Prerequisites

• Basic understanding of Kubernetes concepts
• Knowledge of storage systems
• Familiarity with cloud storage
• Understanding of persistence concepts

Learning Objectives

• Understand Kubernetes storage concepts
• Learn volume management
• Master persistent volumes
• Implement storage classes
• Configure dynamic provisioning

Table of Contents

1. Volumes
2. Persistent Volumes
3. Storage Classes
4. Volume Snapshots
5. Storage Best Practices

Volumes

EmptyDir Volume

apiVersion: v1
kind: Pod
metadata:
  name: test-pod
spec:
  containers:
  - name: test-container
    image: nginx
    volumeMounts:
    - mountPath: /cache
      name: cache-volume
  volumes:
  - name: cache-volume
    emptyDir: {}

HostPath Volume

apiVersion: v1
kind: Pod
metadata:
  name: test-pod
spec:
  containers:
  - name: test-container
    image: nginx
    volumeMounts:
    - mountPath: /test-pd
      name: test-volume
  volumes:
  - name: test-volume
    hostPath:
      path: /data
      type: Directory

Persistent Volumes

PersistentVolume

apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-volume
spec:
  capacity:
    storage: 10Gi
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Retain
  storageClassName: standard
  nfs:
    path: /tmp
    server: 172.17.0.2

PersistentVolumeClaim

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pv-claim
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 5Gi
  storageClassName: standard

Using PVC in Pod

apiVersion: v1
kind: Pod
metadata:
  name: pv-pod
spec:
  containers:
  - name: test-container
    image: nginx
    volumeMounts:
    - mountPath: "/var/www/html"
      name: pv-storage
  volumes:
  - name: pv-storage
    persistentVolumeClaim:
      claimName: pv-claim

Storage Classes

Basic StorageClass

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: standard
provisioner: kubernetes.io/aws-ebs
parameters:
  type: gp2
reclaimPolicy: Retain
allowVolumeExpansion: true

Dynamic Provisioning

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: fast
provisioner: kubernetes.io/aws-ebs
parameters:
  type: io1
  iopsPerGB: "10"
  fsType: ext4

Volume Snapshots

VolumeSnapshotClass

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshotClass
metadata:
  name: csi-hostpath-snapclass
driver: hostpath.csi.k8s.io
deletionPolicy: Delete

VolumeSnapshot

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshot
metadata:
  name: new-snapshot
spec:
  volumeSnapshotClassName: csi-hostpath-snapclass
  source:
    persistentVolumeClaimName: pv-claim

Restore from Snapshot

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: restore-pvc
spec:
  dataSource:
    name: new-snapshot
    kind: VolumeSnapshot
    apiGroup: snapshot.storage.k8s.io
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 10Gi

Storage Best Practices

Volume Security Context

apiVersion: v1
kind: Pod
metadata:
  name: security-context-pod
spec:
  securityContext:
    fsGroup: 2000
  containers:
  - name: sec-ctx-container
    image: nginx
    volumeMounts:
    - name: sec-ctx-vol
      mountPath: /data/demo
  volumes:
  - name: sec-ctx-vol
    persistentVolumeClaim:
      claimName: pv-claim

Resource Quotas

apiVersion: v1
kind: ResourceQuota
metadata:
  name: storage-quota
spec:
  hard:
    persistentvolumeclaims: "10"
    requests.storage: "500Gi"

Best Practices

1. Use appropriate storage types
2. Implement proper backup strategies
3. Configure storage classes correctly
4. Monitor storage usage
5. Implement proper access controls
6. Use volume snapshots
7. Plan for scalability

Common Pitfalls

1. Incorrect storage class selection
2. Poor capacity planning
3. Missing backup strategy
4. Inadequate monitoring
5. Performance issues
6. Security misconfigurations

Implementation Examples

Complete Storage Configuration

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: fast-storage
provisioner: kubernetes.io/aws-ebs
parameters:
  type: io1
  iopsPerGB: "10"
  fsType: ext4
reclaimPolicy: Retain
allowVolumeExpansion: true
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: app-data
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: fast-storage
  resources:
    requests:
      storage: 100Gi
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: web
spec:
  serviceName: "nginx"
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx
        ports:
        - containerPort: 80
          name: web
        volumeMounts:
        - name: www
          mountPath: /usr/share/nginx/html
  volumeClaimTemplates:
  - metadata:
      name: www
    spec:
      accessModes: [ "ReadWriteOnce" ]
      storageClassName: fast-storage
      resources:
        requests:
          storage: 1Gi

Backup Configuration

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshotClass
metadata:
  name: csi-aws-snapclass
driver: ebs.csi.aws.com
deletionPolicy: Retain
parameters:
  description: "Daily backup snapshot"
---
apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshot
metadata:
  name: volume-snap-1
spec:
  volumeSnapshotClassName: csi-aws-snapclass
  source:
    persistentVolumeClaimName: app-data

Resources for Further Learning

• Kubernetes Storage Documentation
• Persistent Volumes
• Storage Classes
• Volume Snapshots

Practice Exercises

1. Create and use PersistentVolumes
2. Implement StorageClasses
3. Configure volume snapshots
4. Set up dynamic provisioning
5. Implement backup strategies