osc-plugin

OpenStackClient reference plugin module

The OSC 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.

oscplugin is a sample OpenStackClient (OSC) plugin implementation that demonstrates how to add commands via OSC's extension mechanism. It adds two commands (plugin list and plugin show) to demonstrate the simple case of new commands that do not require authentication.

Discovery

OSC discovers extensions by enumerating the entry points found under openstack.cli.extension and initializing the given client module.

[entry_points]
openstack.cli.extension =
    oscplugin = oscplugin.plugin

The client module must implement the following interface functions:

• 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)
• 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
• build_option_parser(parser) - Hook to add global options to the parser
• make_client(instance) - Hook to create the client object

OSC enumerates the loaded plugins and loads commands from the entry points defined for the API version:

openstack.oscplugin.v1 =
    plugin_list = oscplugin.v1.plugin:ListPlugin
    plugin_show = oscplugin.v1.plugin:ShowPlugin

Note that OSC defines the group name as openstack.<api-name>.v<version> so the version should not contain the leading 'v' character.

This second step is identical to that performed for all but the Identity client in OSC itself. Identity is special due to the authentication requirements. This limits the ability to add additional auth modules to OSC.

Client

The current implementation of the oscplugin Client class is an empty placeholder. This client object is not equired but OSC's ClientManager will maintain it as required and is the interface point for other plugins to access anything implemented by this plugin.