Kubernetes Persistent Volume Claim

A Kubernetes Persistent Volume Claim (PVC) like sending a request for storage space within a Kubernetes cluster. It’s a resource that allows a pod to request specific storage resources, such as size and access mode, without needing to know the details of the underlying storage implementation. For example, pod asking for storage without knowing all the technical details about how the storage works. Once a PVC is created or we can say once you make this request, Kubernetes will automatically bind it to an available Persistent Volume (PV) that satisfies the request.

This makes it easier for users to request and use storage resources dynamically without having to manage the underlying storage Infrastructure because they don’t have to worry about managing the storage themselves. PVCs are really helpful, especially when you have applications that need to keep data even if the pod restarts or moves around in the cluster.

An Introduction To Kubernetes Volume Snapshots

Kubernetes is an open-source container orchestration platform designed to automate the deployment, scaling, and management of containerized applications with unparalleled efficiency and flexibility to meet fluctuating demand and ensure high availability through the automated self-healing mechanism.

Kubernetes, crafted in the Go programming language and originating from Google’s internal ” Borg ” project, officially emerged as an open-source platform. later subsequent donation to the Cloud Native Computing Foundation (CNCF). Kubernetes has seen exponential growth and adoption, becoming the standard for container orchestration Tools in the Tech industry.

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Kubernetes Volume

One crucial aspect of Kubernetes is managing data persistence, which is where volumes and snapshots come into play. One issue arises when a container crashes or stops, resulting in the loss of the container state and any files created or modified during its lifetime. Upon a crash, kubelet restarts the container with a clean slate, leading to data loss. Additionally, managing shared files among multiple containers within a Pod can be complex. Kubernetes volume abstraction addresses these challenges by providing a solution for persistent storage and shared filesystems across containers....

Kubernetes Persistent Volume

A Kubernetes persistent volume (PV) is a piece of storage provisioned either statically by an administrator or dynamically by a storage class. PV is not dependent on the lifecycle of a pod. PVs provide a way for pods to access durable, persistent storage that can survive pod restarts or rescheduling. PVs are especially useful for stateful applications such as databases where data persistence is critical....

Kubernetes Persistent Volume Specification

It mainly consists of several components...

Persistent Volume (PV) Manifest File

apiVersion: v1kind: PersistentVolumemetadata: name: flask-volumespec: capacity: storage: 1Gi accessModes: - ReadWriteOnce hostPath: path: /data/flask...

Kubernetes Persistent Volume Claim

A Kubernetes Persistent Volume Claim (PVC) like sending a request for storage space within a Kubernetes cluster. It’s a resource that allows a pod to request specific storage resources, such as size and access mode, without needing to know the details of the underlying storage implementation. For example, pod asking for storage without knowing all the technical details about how the storage works. Once a PVC is created or we can say once you make this request, Kubernetes will automatically bind it to an available Persistent Volume (PV) that satisfies the request....

Kubernetes Persistent Volume Claim (PVC) Specification

It mainly consists of several components....

Persistent Volume Claim (PVC) Manifest File

apiVersion: v1kind: PersistentVolumeClaimmetadata: name: flask-claimspec: accessModes: - ReadWriteOnce resources: requests: storage: 1Gi...

Mount the Volume in a Pod

Now, why we do need to Create Pod manifest ? we have already created manifests for Persistent Volume (PV) and Persistent Volume Claim (PVC). these resources are used to provide and claim storage within the Kubernetes cluster....

Pod Manifest File

apiVersion: v1kind: Podmetadata: name: flask-pod labels: app: flask-appspec: containers: - name: flask-container image: DockerHubUsername/your-image-name:tag volumeMounts: - name: flask-volume mountPath: /volume/data volumes: - name: flask-volume PersistentVolumeClaim: claimName: flask-claim...

PV and PVC are created and Mounted in a Pod

To check if a persistent volume and persistent volume claim are created and mounted in a pod we can use following command....

How To Access Application Running Inside Pod?

To access the Application running inside a Kubernetes pod, we need to expose the application either through port forwarding or by creating a Kubernetes Service....

Kubernetes Service Manifest File

apiVersion: v1kind: Servicemetadata: name: flask-servicespec: selector: app: flask-app ports: - protocol: TCP port: 8080 targetPort: 8080 type: NodePort...

Kubernetes Snapshots

Kubernetes volumes snapshots enhance the capabilities of volumes by enabling the creation of snapshots that capture the exact state of volume data at a specific point in time. These snapshots provide a reliable means for backing up, recovering, and cloning data, ensuring data integrity and enabling robust backup solutions for Kubernetes applications....

Benefits of Kubernetes Volumes Snapshots

1. Robust Data Security...

Volume V/s Snapshot

Parameter Volume Snapshot Definition A volume in Kubernetes is a storage abstraction that allows containers within a pod to access shared or persistent data. It provides a way to store and persist data that can be shared among multiple containers within the same pod. A snapshot is a point-in-time copy of the data stored in a volume. It captures the state of the data at a specific moment, allowing users to create backups or clones of their storage resources. Purpose Volumes are used to provide storage to containers within pods. They allow containers to access and store data persistently or temporarily during the lifetime of a pod. Snapshots are used to create backups or clones of data stored in volumes. They provide a way to capture the state of the data at a specific moment, enabling data protection, disaster recovery, and application cloning. Lifecycle Volumes have a lifecycle tied to the pod they are attached to. They are created when the pod is created and destroyed when the pod is deleted. Snapshots have a separate lifecycle independent of the volume or pod. They are created at a specific moment in time and can exist even after the original volume or pod is deleted. Mutability Volumes are mutable, meaning they can be read from and written to by containers within the pod. Changes made to the volume are reflected in real-time. Snapshots are immutable, meaning they cannot be modified after creation. They provide a consistent copy of the data at the time of the snapshot and cannot be altered. Usage Volumes are used to provide persistent storage to application running in Kubernetes pods. They can be used for storing application data, configuration files, and other persistent resources. Snapshots are used for data backup, disaster recovery, and cloning purposes. They enable users to create point-in-time copies of data for archiving, testing, or restoring purposes....

Step-by-Step Implementation of Kubernetes volume Snapshot

Make sure the VolumeSnapshot API is installed in your Kubernetes cluster. This API is required to create and manage volume snapshots....

Apply Custom Resource Definitions (CRDs)

The VolumeSnapshot API requires Custom Resource Definitions (CRDs) to be installed in the cluster....

Note:

Installation of the CRDs is the responsibility of the Kubernetes distribution. Without the required CRDs present, the creation of a VolumeSnapshotClass fails. And you also need to ensure that the required components, including the external snapshotter controller (snapshot-controller, StorageClass) are installed....

Step 1: Create VolumeSnapshotClass

To define custom behaviors for volume snapshots, you can create a VolumeSnapshotClass object. VolumeSnapshotClass provides a way to describe the “classes” of storage when provisioning a volume snapshot....

Step 3: Create VolumeSnapshot

In Kubernetes, a VolumeSnapshot denotes a snapshot of a volume within a storage system....

VolumeSnapshot YAML File

apiVersion: snapshot.storage.k8s.io/v1kind: VolumeSnapshotmetadata: name: volume-snapshotspec: volumeSnapshotClassName: snapshot-class source: persistentVolumeClaimName: flask-claim...

Conclusion

we successfully created Kubernetes volume snapshots We followed the steps to create PersistentVolume (PV), PersistentVolumeClaim (PVC), VolumeSnapshotClass, VolumeSnapshot, and VolumeSnapshotContent. These snapshots provide a point-in-time copy of the data stored in the PersistentVolume, which can be used for backup, cloning, or other data management purposes....

Kubernetes Volume Snapshot – FAQ’s

What is a Kubernetes volume snapshot ?...