Manila share driver hooks
Manila share driver hooks are designed to provide additional possibilities
for each manila-share service; such as any kind of notification and
additional actions before and after share driver calls.
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.
Note
More info about common config options for hooks can be found in
module manila.share.hook
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.
The manila.share.hook.py Module
Module with hook interface for actions performed by share driver.
All available hooks are placed in manila/share/hooks dir.
Hooks are used by share services and can serve several use cases such as
any kind of notification and performing additional backend-specific actions.
-
class
HookBase(configuration, host)
Bases: object
-
execute_periodic_hook(context, periodic_hook_data, *args, **kwargs)
Hook called on periodic basis.
-
execute_post_hook(context=None, func_name=None, pre_hook_data=None, driver_action_results=None, *args, **kwargs)
Hook called after driver’s action.
-
execute_pre_hook(context=None, func_name=None, *args, **kwargs)
Hook called before driver’s action.
-
get_config_option(key)
