# Longhorn-Restoring a PostgreSQL Cluster

# Restoring a PostgreSQL Cluster (CloudNativePG) on Kubernetes Using an Existing Backup & Longhorn

# 1\. Scenario & Goal

Overview (one sentence): We use an existing Longhorn backup to seed a new PostgreSQL cluster (managed by CNPG) in a new Kubernetes cluster via a fixed flow: restore → PVC → VolumeSnapshot → CNPG bootstrap.

# 2\. Procedure

1. Restore the backup (set replica count).
    
    * Restore the required Longhorn backup and set the number of Longhorn replicas for the restored volume (e.g., 2 or 3).
        
    * ![](https://cdn.hashnode.com/res/hashnode/image/upload/v1762253801127/730d4f6d-37f0-4484-b0c7-4a2b7a045e52.png align="center")
        
2. Create a new PVC with a distinct name.
    
    * In the target namespace, create a PersistentVolumeClaim that binds to Longhorn for this restored data. Use a name different from any previous PVC.
        
    * ![](https://cdn.hashnode.com/res/hashnode/image/upload/v1762253975463/77644ef6-2c2d-4880-8ab8-dc4143b0fbc1.png align="center")
        
3. Create a Kubernetes VolumeSnapshot from that PVC
    
    * Using the CSI snapshot API, create a VolumeSnapshot that references the newly created PVC as its source. This snapshot becomes the hand-off artifact to your CNPG bootstrap.
        
    * ```yaml
        apiVersion: snapshot.storage.k8s.io/v1
        kind: VolumeSnapshotClass
        metadata:
          name: longhorn-snapclass
        driver: driver.longhorn.io
        deletionPolicy: Retain
        ---
        apiVersion: snapshot.storage.k8s.io/v1
        kind: VolumeSnapshot
        metadata: { name: VolumeSnapshot-test, namespace: pro }
        spec:
          volumeSnapshotClassName: longhorn-snapclass
          source: { persistentVolumeClaimName: pvc-test }
        ```
        
4. Bootstrap CNPG from the VolumeSnapshot.
    
    * In the CNPG cluster spec, reference that VolumeSnapshot in the bootstrap section so the new PostgreSQL cluster initializes from it.
        
    * ```yaml
        apiVersion: postgresql.cnpg.io/v1
        kind: Cluster
        metadata:
          name: project-postgres-cluster
          namespace: pro
        spec:
          instances: 1
          imageName: ghcr.io/cloudnative-pg/postgresql:17.5
          enableSuperuserAccess: true
          storage:
            storageClass: longhorn
            size: 100Gi
          bootstrap:
            recovery:
              volumeSnapshots:
                storage:
                  apiGroup: snapshot.storage.k8s.io
                  kind: VolumeSnapshot
                  name: VolumeSnapshot-test
        ```
        
    
    * Important note: The PostgreSQL image version must exactly match the image version used in the old cluster from which the backup was taken.
        
    
    # Fainally
    
    Wait until all CNPG pods are Ready and the cluster status is Healthy.
    
    Connect and run simple checks (e.g., record counts, integrity queries) to confirm the dataset is correct.