borgmatic/docs/how-to/add-preparation-and-cleanup-steps-to-backups.md

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Preparation and cleanup hooks

If you find yourself performing prepraration tasks before your backup runs, or cleanup work afterwards, borgmatic hooks may be of interest. Hooks are shell commands that borgmatic executes for you at various points, and they're configured in the hooks section of your configuration file. But if you're looking to backup a database, it's probably easier to use the database backup feature instead.

You can specify before_backup hooks to perform preparation steps before running backups, and specify after_backup hooks to perform cleanup steps afterwards. Here's an example:

hooks:
    before_backup:
        - mount /some/filesystem
    after_backup:
        - umount /some/filesystem

The before_backup and after_backup hooks each run once per configuration file. before_backup hooks run prior to backups of all repositories in a configuration file, right before the create action. after_backup hooks run afterwards, but not if an error occurs in a previous hook or in the backups themselves.

There are additional hooks that run before/after other actions as well. For instance, before_prune runs before a prune action, while after_prune runs after it.

Variable interpolation

The before and after action hooks support interpolating particular runtime variables into the hook command. Here's an example that assumes you provide a separate shell script:

hooks:
    after_prune:
        - record-prune.sh "{configuration_filename}" "{repositories}"

In this example, when the hook is triggered, borgmatic interpolates runtime values into the hook command: the borgmatic configuration filename and the paths of all configured repositories. Here's the full set of supported variables you can use here:

• configuration_filename: borgmatic configuration filename in which the hook was defined
• repositories: comma-separated paths of all repositories configured in the current borgmatic configuration file

Global hooks

You can also use before_everything and after_everything hooks to perform global setup or cleanup:

hooks:
    before_everything:
        - set-up-stuff-globally
    after_everything:
        - clean-up-stuff-globally

before_everything hooks collected from all borgmatic configuration files run once before all configuration files (prior to all actions), but only if there is a create action. An error encountered during a before_everything hook causes borgmatic to exit without creating backups.

after_everything hooks run once after all configuration files and actions, but only if there is a create action. It runs even if an error occurs during a backup or a backup hook, but not if an error occurs during a before_everything hook.

Error hooks

borgmatic also runs on_error hooks if an error occurs, either when creating a backup or running a backup hook. See the monitoring and alerting documentation for more information.

Hook output

Any output produced by your hooks shows up both at the console and in syslog (when run in a non-interactive console). For more information, read about inspecting your backups.

Security

An important security note about hooks: borgmatic executes all hook commands with the user permissions of borgmatic itself. So to prevent potential shell injection or privilege escalation, do not forget to set secure permissions on borgmatic configuration files (chmod 0600) and scripts (chmod 0700) invoked by hooks.