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diff --git a/doc/dev/ceph-volume/plugins.rst b/doc/dev/ceph-volume/plugins.rst new file mode 100644 index 00000000..95bc761e --- /dev/null +++ b/doc/dev/ceph-volume/plugins.rst @@ -0,0 +1,65 @@ +.. _ceph-volume-plugins: + +Plugins +======= +``ceph-volume`` started initially to provide support for using ``lvm`` as +the underlying system for an OSD. It is included as part of the tool but it is +treated like a plugin. + +This modularity, allows for other device or device-like technologies to be able +to consume and re-use the utilities and workflows provided. + +Adding Plugins +-------------- +As a Python tool, plugins ``setuptools`` entry points. For a new plugin to be +available, it should have an entry similar to this in its ``setup.py`` file: + +.. code-block:: python + + setup( + ... + entry_points = dict( + ceph_volume_handlers = [ + 'my_command = my_package.my_module:MyClass', + ], + ), + +The ``MyClass`` should be a class that accepts ``sys.argv`` as its argument, +``ceph-volume`` will pass that in at instantiation and call them ``main`` +method. + +This is how a plugin for ``ZFS`` could look like for example: + +.. code-block:: python + + class ZFS(object): + + help_menu = 'Deploy OSDs with ZFS' + _help = """ + Use ZFS as the underlying technology for OSDs + + --verbose Increase the verbosity level + """ + + def __init__(self, argv): + self.argv = argv + + def main(self): + parser = argparse.ArgumentParser() + args = parser.parse_args(self.argv) + ... + +And its entry point (via ``setuptools``) in ``setup.py`` would looke like: + +.. code-block:: python + + entry_points = { + 'ceph_volume_handlers': [ + 'zfs = ceph_volume_zfs.zfs:ZFS', + ], + }, + +After installation, the ``zfs`` subcommand would be listed and could be used +as:: + + ceph-volume zfs |