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

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)