ceph/doc/dev/ceph-volume/plugins.rst

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.. _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