=======
Plugins
=======
The OpenStackClient plugin system is designed so that the plugin need only be
properly installed for OSC to find and use it. It utilizes the
``setuptools`` entry points mechanism to advertise to OSC the
plugin module and supported commands.
Adoption
========
OpenStackClient promises to provide first class support for the following
OpenStack services: Compute, Identity, Image, Object Storage, Block Storage
and Network (core objects). These services are considered essential
to any OpenStack deployment.
Other OpenStack services, such as Orchestration or Telemetry may create an
OpenStackClient plugin. The source code will not be hosted by
OpenStackClient.
The following is a list of projects that are an OpenStackClient plugin.
- aodhclient
- gnocchiclient\*\*
- python-barbicanclient
- python-congressclient
- python-cueclient\*\*
- python-designateclient
- python-heatclient
- python-ironicclient
- python-ironic-inspector-client
- python-mistralclient
- python-muranoclient
- python-neutronclient\*\*\*
- python-saharaclient
- python-searchlightclient
- python-senlinclient
- python-tripleoclient\*\*
- python-watcherclient\*\*
- python-zaqarclient
\*\* Note that some clients are not listed in global-requirements.
\*\*\* Project contains advanced network services.
The following is a list of projects that are not an OpenStackClient plugin.
- python-troveclient
- python-magnumclient
- python-ceilometerclient
- python-solumclient
Implementation
==============
Client module
-------------
Plugins are discovered by enumerating the entry points
found under :py:mod:`openstack.cli.extension` and initializing the specified
client module.
.. code-block:: ini
[entry_points]
openstack.cli.extension =
oscplugin = oscplugin.client
The client module must define the following top-level variables:
* ``API_NAME`` - A string containing the plugin API name; this is
the name of the entry point declaring the plugin client module
(``oscplugin = ...`` in the example above) and the group name for
the plugin commands (``openstack.oscplugin.v1 =`` in the example below).
OSC reserves the following API names: ``compute``, ``identity``,
``image``, ``network``, ``object_store`` and ``volume``.
* ``API_VERSION_OPTION`` (optional) - If set, the name of the API
version attribute; this must be a valid Python identifier and
match the destination set in ``build_option_parser()``.
* ``API_VERSIONS`` - A dict mapping a version string to the client class
The client module must implement the following interface functions:
* ``build_option_parser(parser)`` - Hook to add global options to the parser
* ``make_client(instance)`` - Hook to create the client object
OSC enumerates the plugin commands from the entry points in the usual manner
defined for the API version:
.. code-block:: ini
openstack.oscplugin.v1 =
plugin_list = oscplugin.v1.plugin:ListPlugin
plugin_show = oscplugin.v1.plugin:ShowPlugin
Note that OSC defines the group name as :py:mod:`openstack.<api-name>.v<version>`
so the version should not contain the leading 'v' character.
.. code-block:: python
from osc_lib import utils
DEFAULT_API_VERSION = '1'
# Required by the OSC plugin interface
API_NAME = 'oscplugin'
API_VERSION_OPTION = 'os_oscplugin_api_version'
API_VERSIONS = {
'1': 'oscplugin.v1.client.Client',
}
# Required by the OSC plugin interface
def make_client(instance):
"""Returns a client to the ClientManager
Called to instantiate the requested client version. instance has
any available auth info that may be required to prepare the client.
:param ClientManager instance: The ClientManager that owns the new client
"""
plugin_client = utils.get_client_class(
API_NAME,
instance._api_version[API_NAME],
API_VERSIONS)
client = plugin_client()
return client
# Required by the OSC plugin interface
def build_option_parser(parser):
"""Hook to add global options
Called from openstackclient.shell.OpenStackShell.__init__()
after the builtin parser has been initialized. This is
where a plugin can add global options such as an API version setting.
:param argparse.ArgumentParser parser: The parser object that has been
initialized by OpenStackShell.
"""
parser.add_argument(
'--os-oscplugin-api-version',
metavar='<oscplugin-api-version>',
help='OSC Plugin API version, default=' +
DEFAULT_API_VERSION +
' (Env: OS_OSCPLUGIN_API_VERSION)')
return parser
Client usage of OSC interfaces
------------------------------
OSC provides the following interfaces that may be used to implement
the plugin commands:
.. code-block:: python
# osc-lib interfaces available to plugins:
from osc_lib.cli import parseractions
from osc_lib.command import command
from osc_lib import exceptions
from osc_lib import logs
from osc_lib import utils
class DeleteMypluginobject(command.Command):
"""Delete mypluginobject"""
...
def take_action(self, parsed_args):
# Client manager interfaces are available to plugins.
# This includes the OSC clients created.
client_manager = self.app.client_manager
...
return
OSC provides the following interfaces that may be used to implement
unit tests for the plugin commands:
.. code-block:: python
# OSC unit test interfaces available to plugins:
from openstackclient.tests import fakes
from openstackclient.tests import utils
...
Requirements
------------
OSC must be included in ``requirements.txt`` or ``test-requirements.txt``
for the plugin project. Update ``requirements.txt`` if the plugin project
considers the CLI a required feature. Update ``test-requirements.txt`` if
the plugin project can be installed as a library with the CLI being an
optional feature (available when OSC is also installed).
.. code-block:: ini
python-openstackclient>=X.Y.Z # Apache-2.0
Checklist for adding new OpenStack plugins
==========================================
Creating the initial plugin described above is the first step. There are a few
more steps needed to fully integrate the client with openstackclient.
Add the command checker to your CI
----------------------------------
#. Modify the section of ``zuul/layout.yaml`` related to your repository to
add ``osc-plugin-jobs`` to the list of job templates for your project.
This job checks that to see if any new commands are: duplicated, missing
entry points, or have overlap; across all openstackclient plugins.
#. Update ``jenkins/scripts/check-osc-plugins.sh`` to include your new
library to be installed from source. This is essential in running the
previously mentioned check job. Simply add
``install_from_source python-fooclient`` to the block of code where all
other clients are installed.
Changes to python-openstackclient
---------------------------------
#. In ``doc/source/plugins.rst``, update the `Adoption` section to reflect the
status of the project.
#. Update ``doc/source/commands.rst`` to include objects that are defined by
fooclient's new plugin.
#. Update ``doc/source/plugin-commands.rst`` to include the entry point defined
in fooclient. We use `sphinxext`_ to automatically document commands that
are used.
#. Update ``test-requirements.txt`` to include fooclient. This is necessary
to auto-document the commands in the previous step.
.. _sphinxext: http://docs.openstack.org/developer/stevedore/sphinxext.html