How Stash Backups & Restores Etcd Database

Stash v2022.09.29 supports backup and restore operation of many databases. This guide will give you an overview of how Etcd database backup and restore process works in Stash.

Backup

Stash supports taking backup of Etcd database using etcdctl. It is the most flexible way to perform backup and restore of Etcd database.

How Backup Works

The following diagram shows how Stash takes backup of a Etcd 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 the 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 takes snapshot of the targeted database using etcdctl and uploads the snapshot to the backend. Stash stores the snapshot temporarily in a directory before uploading that into the backend. You can limit the temporary directory size using spec.TempDir field of BackupConfiguration crd.

12. Finally, when the backup is complete, 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 completion.

How Restore from Backup Works

The following diagram shows how Stash restores an Etcd database from a backup. 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 snapshot from the backend and restore that snapshot into the Etcd database. Stash stores the downloaded files temporarily before inserting into the targeted database.

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

Next Steps

• Backup your Etcd database using Stash following the guide from here.