manila/doc/source/contributor/services.rst
Tom Barron 90060722a9 doc migration: new directory layout
This patch introduces a new directory layout
in doc/source in conformance with the OpenStack
manuals project migration spec [1], moves the
existing content in manila/doc/source into the
new directories, and adjusts index files accordingly.

This is the first step in the migration process
as outlined in the spec.

[1] https://specs.openstack.org/openstack/docs-specs/specs/pike/os-manuals-migration.html

Partial-Bug: #1706181
Needed-By: I7924d94b82e7c8d9716bad7a219fc38c57970773
Depends-On: Ifc80fc56648cef74c85464321d1850e8c68449a0
Depends-On: Ia750cb049c0f53a234ea70ce1f2bbbb7a2aa9454
Change-Id: Ieea33262101a1d2459492c1c8aaac5fe042279f6
2017-08-24 09:16:25 -04:00

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..
Copyright 2010-2011 United States Government as represented by the
Administrator of the National Aeronautics and Space Administration.
All Rights Reserved.
Licensed under the Apache License, Version 2.0 (the "License"); you may
not use this file except in compliance with the License. You may obtain
a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
License for the specific language governing permissions and limitations
under the License.
.. _service_manager_driver:
Services, Managers and Drivers
==============================
The responsibilities of Services, Managers, and Drivers, can be a bit confusing to people that are new to manila. This document attempts to outline the division of responsibilities to make understanding the system a little bit easier.
Currently, Managers and Drivers are specified by flags and loaded using utils.load_object(). This method allows for them to be implemented as singletons, classes, modules or objects. As long as the path specified by the flag leads to an object (or a callable that returns an object) that responds to getattr, it should work as a manager or driver.
The :mod:`manila.service` Module
--------------------------------
.. automodule:: manila.service
:noindex:
:members:
:undoc-members:
:show-inheritance:
The :mod:`manila.manager` Module
--------------------------------
.. automodule:: manila.manager
:noindex:
:members:
:undoc-members:
:show-inheritance:
Implementation-Specific Drivers
-------------------------------
A manager will generally load a driver for some of its tasks. The driver is responsible for specific implementation details. Anything running shell commands on a host, or dealing with other non-python code should probably be happening in a driver.
Drivers should minimize touching the database, although it is currently acceptable for implementation specific data. This may be reconsidered at some point.
It usually makes sense to define an Abstract Base Class for the specific driver (i.e. VolumeDriver), to define the methods that a different driver would need to implement.