Manila share driver hooks¶

Possibilities¶

• Perform actions before some share driver method calls.

• Perform actions after some share driver method calls with results of

  driver call and preceding hook call.

• Call additional ‘periodic’ hook each ‘N’ ticks.

• Possibility to update results of driver’s action by post-running hook.

Features¶

• Errors in hook execution can be suppressed.

• Any hook can be disabled.

• Any amount of hook instances can be run at once for each manila-share

  service.

Limitations¶

• Hooks approach is not asynchronous. That is, if we run hooks, and

  especially, more than one hook instance, then all of them will be executed in one thread.

Implementation in share drivers¶

Share drivers can [re]define method get_periodic_hook_data that runs with each execution of ‘periodic’ hook and receives list of shares (as parameter) with existing access rules. So, each share driver, for each of its shares can add/update some information that will be used then in the periodic hook.

What is required for writing new ‘hook’ implementation?¶

All implementations of ‘hook’ interface are expected to be in ‘manila/share/hooks’. Each implementation should inherit class ‘manila.share.hook:HookBase’ and redefine its abstract methods.

How to use ‘hook’ implementations?¶

Just set config option ‘hook_drivers’ in driver’s config group. For example:

[MY_DRIVER]
hook_drivers=path.to:FooClass,path.to:BarClass

Then all classes defined above will be initialized. In the same config group, any config option of hook modules can be redefined too.

Driver methods that are wrapped with hooks¶

• allow_access
• create_share_instance
• create_snapshot
• delete_share_instance
• delete_share_server
• delete_snapshot
• deny_access
• extend_share
• init_host
• manage_share
• publish_service_capabilities
• shrink_share
• unmanage_share
• create_share_replica
• promote_share_replica
• delete_share_replica
• update_share_replica
• create_replicated_snapshot
• delete_replicated_snapshot
• update_replicated_snapshot

Above list with wrapped methods can be extended in future.