Dean Troyer fbc412e533 Multiple API version support
* Use multiple entry point groups to represent each API+version
  combination supported
* Add some tests

Try it out:
* Right now only '* user' commands have multiple overlapping versions;
  you can see the selection between v2.0 and v3 by looking at the
  command help output for 'tenant' vs 'project':

  os --os-identity-api-version=2.0 help set user
  os --os-identity-api-version=3 help set user

Change-Id: I7114fd246843df0243d354a7cce697810bb7de62
2013-02-06 11:36:28 -06:00

61 lines
2.2 KiB
ReStructuredText

========
Commands
========
Command Structure
=================
OpenStack Client uses a command form ``verb object``.
Note that 'object' here refers to the target of a command's action. In coding
discussions 'object' has its usual Python meaning. Go figure.
Commands take the form::
openstack [<global-options>] <verb> <object> [<command-local-arguments>]
Command Arguments
-----------------
* All long option names use two dashes ('--') as the prefix and a single dash
('-') as the interpolation character. Some common options also have the
traditional single letter name prefixed by a single dash ('-').
* Global options generally have a corresponding environment variable that
may also be used to set the value. If both are present, the command-line
option takes priority. The environment variable names can be derived from
the option name by dropping the leading '--', converting all embedded dashes
('-') to underscores ('_'), and converting the name to upper case.
* Positional arguments trail command options. In commands that require two or
more objects be acted upon, such as 'attach A to B', both objects appear
as positional arguments. If they also appear in the command object they are
in the same order.
Implementation
==============
The command structure is designed to support seamless addition of extension
command modules via entry points. The extensions are assumed to be subclasses
of Cliff's command.Command object.
Command Entry Points
--------------------
Commands are added to the client using distribute's entry points in ``setup.py``.
There is a single common group ``openstack.cli`` for commands that are not versioned,
and a group for each combination of OpenStack API and version that is
supported. For example, to support Identity API v3 there is a group called
``openstack.identity.v3`` that contains the individual commands. The command
entry points have the form::
"verb_object=fully.qualified.module.vXX.object:VerbObject"
For example, the 'list user' command fir the Identity API is identified in
``setup.py`` with::
'openstack.identity.v3': [
# ...
'list_user=openstackclient.identity.v3.user:ListUser',
# ...
],