charms.openstack/charms_openstack/bus.py

85 lines
2.7 KiB
Python

# Copyright 2014-2018 Canonical Limited.
#
# This file is part of charms.reactive.
#
# charms.reactive is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License version 3 as
# published by the Free Software Foundation.
#
# charm-helpers is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with charm-helpers. If not, see <http://www.gnu.org/licenses/>.
import importlib
import os
import charmhelpers.core.hookenv as hookenv
# Code below is based on charms.reactive.bus
def discover(search_path=None):
"""Discover Openstack handlers based on convention.
Handlers will be loaded from the following directory and its
subdirectories:
* ``$CHARM_DIR/lib/charm/openstack``
The Python files will be imported and decorated functions registered.
:param search_path: Override path to search for handlers.
:type search_path: Optional[str]
"""
if not search_path:
search_path = os.path.join(
hookenv.charm_dir(), 'lib', 'charm', 'openstack')
base_path = os.path.dirname(search_path)
for dirpath, dirnames, filenames in os.walk(search_path):
for filename in filenames:
filepath = os.path.join(dirpath, filename)
_register_handlers_from_file(base_path, filepath)
def _load_module(root, filepath):
"""Import the supplied module.
:param root: Module root directory eg directory that the import is
relative to.
:type root: str
:param filepath: Module file.
:type filepath: str
"""
assert filepath.startswith(root + os.sep)
assert filepath.endswith('.py')
package = os.path.basename(root)
module = filepath[len(root):-3].replace(os.sep, '.')
if module.endswith('.__init__'):
module = module[:-9]
# Standard import.
importlib.import_module(package + module)
def _register_handlers_from_file(root, filepath):
"""Import the supplied module if its a good candidate.
:param root: Module root directory eg directory that the import is
relative to.
:type root: str
:param filepath: Module file.
:type filepath: str
"""
no_exec_blacklist = (
'.md', '.yaml', '.txt', '.ini',
'makefile', '.gitignore',
'copyright', 'license')
if filepath.lower().endswith(no_exec_blacklist):
# Don't load handlers with one of the blacklisted extensions
return
if filepath.endswith('.py'):
_load_module(root, filepath)