cinder/doc/source/contributor/services.rst
Jay S. Bryant 1423480fb6 Make doc/source directory compliant with design in spec
The following spec defines what each project's doc/source
directory is supposed to look like:

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

I had not yet moved existing content to follow this design.
This patch does that, moving the devref to the
'contributor' directory.  It also moves the CLI
related documentation into the 'cli' directory.  I have
updated the autodoc generation to now create the api
documentation in 'doc/source/contributor/api'.

This patch also creates a template for future documentation
contribution.  I have created all of the directories
recommended by the spec and have included documentation
as to what should go in each directory.

The index file is updated to point at the new locations for
existing content.

'doc/.gitignore' is updated so that it won't complain about the
automatically generated 'doc/contributor/api' directory.

Change-Id: I55c50fa0b7c1d06c91e40dbcfd11b1c8e8378aa6
2017-07-19 15:59:02 -05:00

2.4 KiB

Services, Managers and Drivers

The responsibilities of Services, Managers, and Drivers, can be a bit confusing to people that are new to cinder. 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 cinder.service Module

cinder.service

The cinder.manager Module

cinder.manager

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.