KubeStash Backup and Restore Hooks

KubeStash supports executing custom commands before and after backup or restore process. This is called hook in KubeStash. This guide will give you an overview of what kind of hooks you can execute, how the hooks get executed, and how the hooks behave in different scenarios.

Types of Hooks

We can categorize KubeStash backup and restore hooks based on the action they perform and based on their execution order.

Based on Action

Based on the action of a hook, we can categorize them into four different categories. These are the followings:

• HTTPGet: Executes an HTTP GET request before/after the backup/restore process. The hook is considered successful if the return code is between 200 and 400.

• HTTPPost: Executes an HTTP POST request before/after the backup/restore process. Like HTTPGet, the hook is considered successful if the return code is between 200 and 400.

• TCPSocket: Performs a TCP check against the provided URL on a specific port before/after the backup/restore process. The hook is considered successful if the targeted port is open.

• Exec: Executes commands inside a targeted container before/after the backup/restore process. The hook is considered successful if the command executes with exit code 0.

Based on Backup & Restore

Based on the backup & restore, we can categorize the hooks into two different categories. These are the followings:

• Backup Hook: Backup Hook specifies the hook that will be executed before and/or after backup. Based on the execution order, we can categorize each backup hook into two different phases. These are the followings:

  • PreBackup Hook: PreBackup Hook specifies the hook that will be executed before backup.

  • PostBackup Hook: PostBackup Hook specifies the hook that will be executed after backup

• Restore Hook: Restore Hook specifies the hook that will be executed before and/or after restore. Based on the execution order, we can categorize each restore hook into two different phases. These are the followings:

  • PreRestore Hook: PreRestore Hook specifies the hook that will be executed before restore.

  • PostRestore Hook: PostRestore Hook specifies the hook that will be executed after restore.

Based on Hook Executor

Based on the hook executor, we can categorize the hooks into three different categories. These are the followings:

• Pod Executor Hook: In pod executor hook, the hook is executed by the selected Pod(s). We can specify the criteria in PodHookExecutorSpec that will be used to select the pod which will execute the hook.

• Operator Executor Hook: In operator executor hook, the hook is executed by the KubeStash operator.

• Function Executor Hook: In function executor hook, the hook is executed by a Job. We can create a Function and define the Function and its parameters in FunctionHookExecutorSpec that will be used to create hook executor job.

Hook’s Behaviors

Now, we are going to discuss what will happen when a hook fails or backup/restore process fails.

preBackup or preRestore hook

If a preBackup or preRestore hook fails to execute, the rest of the backup/restore process will be skipped and the respective BackupSession/RestoreSession will be marked as Failed.

postBackup or postRestore hook

If the backup or restore process fails then the respective postBackup or postRestore hook will be executed according to the policy specified in the executionPolicy field of the respective hook in BackupConfiguration / RestoreSession. The current acceptable values and behaviors are:

• Always: The hook will be executed after the backup/restore process regardless of whether the backup/restore has failed or succeeded. This is the default behavior.
• OnSuccess: The hook will be executed after the backup/restore process only if the backup/restore has succeeded.
• OnFailure: The hook will be executed after the backup/restore process only if the backup/restore has failed.

If the postBackup or postRestore hook fails, the respective BackupSession or RestoreSession will be marked as Failed.