2.2 KiB
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 setuptools's entry points in
setup.cfg. 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:VerbObjectFor example, the 'list user' command fir the Identity API is
identified in setup.cfg with:
openstack.identity.v3 =
# ...
list_user = openstackclient.identity.v3.user:ListUser
# ...