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Backup & Restore Elasticsearch Using Stash

KubeDB uses Stash to backup and restore databases. Stash by AppsCode is a cloud native data backup and recovery solution for Kubernetes workloads. Stash utilizes restic to securely backup stateful applications to any cloud or on-prem storage backends (for example, S3, GCS, Azure Blob storage, Minio, NetApp, Dell EMC etc.).

  

How Backup Works

The following diagram shows how Stash takes a backup of an Elasticsearch database. Open the image in a new tab to see the enlarged version.

The backup process consists of the following steps:

1. At first, a user creates a secret with access credentials of the backend where the backed up data will be stored.

2. Then, she creates a Repository crd that specifies the backend information along with the secret that holds the credentials to access the backend.

3. Then, she creates a BackupConfiguration crd targeting the AppBinding crd of the desired database. The BackupConfiguration object also specifies the Task to use to backup the database.

4. Stash operator watches for BackupConfiguration crd.

5. Once Stash operator finds a BackupConfiguration crd, it creates a CronJob with the schedule specified in BackupConfiguration object to trigger backup periodically.

6. On the next scheduled slot, the CronJob triggers a backup by creating a BackupSession crd.

7. Stash operator also watches for BackupSession crd.

8. When it finds a BackupSession object, it resolves the respective Task and Function and prepares a Job definition to backup.

9. Then, it creates the Job to backup the targeted database.

10. The backup Job reads necessary information to connect with the database from the AppBinding crd. It also reads backend information and access credentials from Repository crd and Storage Secret respectively.

11. Then, the Job dumps the targeted database and uploads the output to the backend. Stash stores the dumped files temporarily before uploading into the backend. Hence, you should provide a PVC template using spec.interimVolumeTemplate field of BackupConfiguration crd to use to store those dumped files temporarily.

12. Finally, when the backup is completed, the Job sends Prometheus metrics to the Pushgateway running inside Stash operator pod. It also updates the BackupSession and Repository status to reflect the backup procedure.

How Restore Process Works

The following diagram shows how Stash restores backed up data into an Elasticsearch database. Open the image in a new tab to see the enlarged version.

The restore process consists of the following steps:

1. At first, a user creates a RestoreSession crd targeting the AppBinding of the desired database where the backed up data will be restored. It also specifies the Repository crd which holds the backend information and the Task to use to restore the target.

2. Stash operator watches for RestoreSession object.

3. Once it finds a RestoreSession object, it resolves the respective Task and Function and prepares a Job definition to restore.

4. Then, it creates the Job to restore the target.

5. The Job reads necessary information to connect with the database from respective AppBinding crd. It also reads backend information and access credentials from Repository crd and Storage Secret respectively.

6. Then, the job downloads the backed up data from the backend and insert into the desired database. Stash stores the downloaded files temporarily before inserting into the targeted database. Hence, you should provide a PVC template using spec.interimVolumeTemplate field of RestoreSession crd to use to store those restored files temporarily.

7. Finally, when the restore process is completed, the Job sends Prometheus metrics to the Pushgateway and update the RestoreSession status to reflect restore completion.

Next Steps

• Backup your Elasticsearch databases using Stash following the guide from here.
• Configure a generic backup template for all the Elasticsearch databases of your cluster using Stash Auto-backup by following the guide from here.
• Customize the backup & restore process for your cluster by following the guides from here.