Clone a database cluster in Kubernetes using a Cloud Storage backup

This page shows you how to clone a database cluster in Kubernetes using a Cloud Storage backup of an AlloyDB Omni database cluster.

The following workflow explains the steps used to clone:

Create and apply the DBCluster manifest file on the target database cluster with the livenessProbe parameter disabled.
Create and configure the pgbackrest.conf file to access the Cloud Storage backup.
Use pgBackRest commands to verify you can access source backups.
Use pgBackRest commands to restore the backup to the target database cluster.

Before you begin

Make sure you have access to the full path of the Cloud Storage bucket where your source database cluster backup is stored. This is the same path you used when you created the BackupPlan resource for your source database cluster.
Create a target AlloyDB Omni database cluster. For more information about installing AlloyDB Omni on Kubernetes, see Create a database cluster.
Ensure you are logged in to the database as the postgres user.

Create a database cluster in a target database cluster

Create a database cluster by temporarily disabling the livenessProbe parameter while the restore process completes.

Create the DBCluster resource manifest file:
```
  apiVersion: v1
  kind: Secret
  metadata:
    name: db-pw-DB_CLUSTER_NAME
  type: Opaque
  data:
    DB_CLUSTER_NAME: "ENCODED_PASSWORD"
  ---
  apiVersion: alloydbomni.dbadmin.goog/v1
  kind: DBCluster
  metadata:
    name: DB_CLUSTER_NAME
  spec:
    primarySpec:
      availabilityOptions:
        livenessProbe: "Disabled"
      adminUser:
        passwordRef:
          name: db-pw-DB_CLUSTER_NAME
      resources:
        cpu: CPU_COUNT
        memory: MEMORY_SIZE
        disks:
        - name: DataDisk
          size: DISK_SIZE
          storageClass: standard
```
Replace the following:
- DB_CLUSTER_NAME: the name of this database cluster—for example, my-db-cluster.
- ENCODED_PASSWORD: the database login password for the default postgres user role, encoded as a base64 string—for example, Q2hhbmdlTWUxMjM= for ChangeMe123.
- CPU_COUNT: the number of CPUs available to each database instance in this database cluster.
- MEMORY_SIZE: the amount of memory per database instance of this database cluster. We recommend setting this to 8 gigabytes per CPU. For example, if you set cpu to 2 earlier in this manifest, then we recommend setting memory to 16Gi.
- DISK_SIZE: the disk size per database instance—for example, 10Gi.
Apply the manifest file:
```
  kubectl apply -f DBCLUSTER_FILENAME
```
Replace the following:
- DBCLUSTER_FILENAME: the name of the DBCluster manifest file created in the previous step.

Use the kubectl describe command to verify that the database cluster resource is in the READY status.

Configure the `pgBackRest` file

Configure the pgBackRest file to enable the target database cluster to access the Cloud Storage bucket where source backups reside.

In your target database cluster, find the database cluster pod details:

  kubectl get pod -l "alloydbomni.internal.dbadmin.goog/dbcluster=<var>DB_CLUSTER_NAME</var>, alloydbomni.internal.dbadmin.goog/task-type=database"

The response includes the name of the cluster database pod.

Log into the pod:
```
  kubectl exec -ti DATABASE_POD_NAME  -- /bin/bash
```
Replace the following:
- DATABASE_POD_NAME: the name of the database cluster pod from the previous step.
Stop the pod before updating the pgBackRest configuration file:
```
  supervisorctl.par stop postgres
```
Create a pgBackRest configuration file to access backups stored in Cloud Storage:
```
  cat << EOF > /backup/pgbackrest.conf
  [db]
  pg1-path=/mnt/disks/pgsql/data
  pg1-socket-path=/tmp
  pg1-user=pgbackrest
  [global]
  log-path=/obs/pgbackrest
  log-level-file=info
  repo1-type=gcs
  repo1-gcs-bucket=GCS_SOURCE_BACKUP_BUCKET_NAME
  repo1-path=GCS_SOURCE_BACKUP_BUCKET_PATH
  repo1-storage-ca-file=/etc/ssl/certs/ca-certificates.crt
  repo1-retention-full=9999999
  repo1-gcs-key-type=auto
```
Replace the following:
- GCS_SOURCE_BACKUP_BUCKET_NAME: the name of the Cloud Storage bucket that you created when creating the BackupPlan resource manifest file for the source database cluster. This is not the full URL to the bucket; don't prefix the bucket name with gs://.
- GCS_SOURCE_BACKUP_BUCKET_PATH: the path of the directory that the AlloyDB Omni Operator writes backups into, within the Cloud Storage bucket for the source database cluster. The path must be absolute, beginning with /.
The repo1-gcs-key-type is set to auto to use the instance's service account. For more information about other options, see GCS Repository Key Type Option.

Verify source backups in the target database cluster

Run pgBackRest commands to verify that the source database cluster backups are accessible on the target database cluster.

pgbackrest --config-path=/backup --stanza=db --repo=1 info

The following is a sample response:

  stanza: db
      status: ok
      cipher: none
      db (current)
          wal archive min/max (15): 000000010000000000000002/00000001000000000000000D
          full backup: 20240213-231400F
              timestamp start/stop: 2024-02-13 23:14:00+00 / 2024-02-13 23:17:14+00
              wal start/stop: 000000010000000000000003 / 000000010000000000000003
              database size: 38.7MB, database backup size: 38.7MB
              repo1: backup set size: 4.6MB, backup size: 4.6MB
          incr backup: 20240213-231400F_20240214-000001I
              timestamp start/stop: 2024-02-14 00:00:01+00 / 2024-02-14 00:00:05+00
              wal start/stop: 00000001000000000000000D / 00000001000000000000000D
              database size: 38.7MB, database backup size: 488.3KB
              repo1: backup set size: 4.6MB, backup size: 84.2KB
              backup reference list: 20240213-231400F

The timestamps in the response are used either to restore the full backup or to restore from a point in time from the recovery window.

Restore the backup in the target database cluster

After you identify the backup or a point in time you want to restore to, run pgBackRest commands in your target database cluster. For more information about these commands, see Restore Command.

The following are some sample pgBackRest restore commands:

Restore from a backup

pgbackrest --config-path=/backup --stanza=db --repo=1 restore --set=20240213-231400F --type=immediate --target-action=promote --delta --link-all --log-level-console=info

Restore from a point in time

pgbackrest --config-path=/backup --stanza=db --repo=1 restore --target="2024-01-22 11:27:22" --type=time --target-action=promote --delta --link-all --log-level-console=info

Restart the pod

After the restore command completes successfully, you can start the postgres process.

supervisorctl.par start postgres

After the postgres process starts, you can connect to the primary instance and run queries to verify that the data is restored from the backup. For more information, see Connect to AlloyDB Omni running on Kubernetes.

What's next

Clone a database cluster in Kubernetes using a local backup