extension_meta Module

The metaclass handles extension registration.

AppExtension is registered in init, it is applied to all triggers. FuncExtension is registered in call, as users need to instantiate it inside hook script.

After registration, the extension class will be flatten into the following structure to speed up worker lookup:

_func_exts[<trigger_name>].<hook_name>.(ext_name, ext_impl) (e.g. _func_exts['HttpTrigger'].pre_invocation.ext_impl)

_app_exts.<hook_name>.(ext_name, ext_impl) (e.g. _app_exts.pre_invocation_app_level.ext_impl)

The extension tree information is stored in _info for diagnostic purpose. The dictionary is serializable to json:

_info['FuncExtension'][''] = list() _info['AppExtension'] = list()

Executes on 'import extension', once the AppExtension class is loaded, call the setup() method and add the life-cycle hooks into _app_exts.