ansible/lib/ansible/utils/plugins.py

# (c) 2012, Daniel Hokka Zakrisson <daniel@hozac.com>
#
# This file is part of Ansible
#
# Ansible is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Ansible 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Ansible.  If not, see <http://www.gnu.org/licenses/>.

import os
import os.path
import sys
import glob
import imp
from ansible import constants as C
from ansible import errors

MODULE_CACHE = {}
PATH_CACHE = {}
PLUGIN_PATH_CACHE = {}
_basedirs = []

def push_basedir(basedir):
    # avoid pushing the same absolute dir more than once
    basedir = os.path.abspath(basedir)
    if basedir not in _basedirs:
        _basedirs.insert(0, basedir)

class PluginLoader(object):

    '''
    PluginLoader loads plugins from the configured plugin directories.

    It searches for plugins by iterating through the combined list of
    play basedirs, configured paths, and the python path.
    The first match is used.
    '''

    def __init__(self, class_name, package, config, subdir, aliases={}):

        self.class_name         = class_name
        self.package            = package
        self.config             = config
        self.subdir             = subdir
        self.aliases            = aliases

        if not class_name in MODULE_CACHE:
            MODULE_CACHE[class_name] = {}
        if not class_name in PATH_CACHE:
            PATH_CACHE[class_name] = None
        if not class_name in PLUGIN_PATH_CACHE:
            PLUGIN_PATH_CACHE[class_name] = {}

        self._module_cache      = MODULE_CACHE[class_name]
        self._paths             = PATH_CACHE[class_name]
        self._plugin_path_cache = PLUGIN_PATH_CACHE[class_name]

        self._extra_dirs = []

    def print_paths(self):
        ''' Returns a string suitable for printing of the search path '''

        # Uses a list to get the order right
        ret = []
        for i in self._get_paths():
            if i not in ret:
                ret.append(i)
        return os.pathsep.join(ret)

    def _get_package_paths(self):
        ''' Gets the path of a Python package '''

        paths = []
        if not self.package:
            return []
        if not hasattr(self, 'package_path'):
            m = __import__(self.package)
            parts = self.package.split('.')[1:]
            self.package_path = os.path.join(os.path.dirname(m.__file__), *parts)
            paths.append(self.package_path)
            return paths
        else:
            return [ self.package_path ]

    def _get_paths(self):
        ''' Return a list of paths to search for plugins in '''

        if self._paths is not None:
            return self._paths

        ret = []
        ret += self._extra_dirs
        for basedir in _basedirs:
            fullpath = os.path.abspath(os.path.join(basedir, self.subdir))
            if os.path.isdir(fullpath):
                files = glob.glob("%s/*" % fullpath)
                for file in files:
                    if os.path.isdir(file) and file not in ret:
                        ret.append(file)
                if fullpath not in ret:
                    ret.append(fullpath)

        # look in any configured plugin paths, allow one level deep for subcategories 
        configured_paths = self.config.split(os.pathsep)
        for path in configured_paths:
            path = os.path.abspath(os.path.expanduser(path))
            contents = glob.glob("%s/*" % path)
            for c in contents:
                if os.path.isdir(c) and c not in ret:
                    ret.append(c)       
            if path not in ret:
                ret.append(path)

        # look for any plugins installed in the package subtree
        ret.extend(self._get_package_paths())

        self._paths = ret

        return ret


    def add_directory(self, directory, with_subdir=False):
        ''' Adds an additional directory to the search path '''

        self._paths = None
        directory = os.path.abspath(directory)

        if directory is not None:
            if with_subdir:
                directory = os.path.join(directory, self.subdir)
            if directory not in self._extra_dirs:
                self._extra_dirs.append(directory)

    def find_plugin(self, name):
        ''' Find a plugin named name '''

        if name in self._plugin_path_cache:
            return self._plugin_path_cache[name]

        suffix = ".py"
        if not self.class_name:
            suffix = ""

        for i in self._get_paths():
            path = os.path.join(i, "%s%s" % (name, suffix))
            if os.path.isfile(path):
                self._plugin_path_cache[name] = path
                return path

        return None

    def has_plugin(self, name):
        ''' Checks if a plugin named name exists '''

        return self.find_plugin(name) is not None

    __contains__ = has_plugin

    def get(self, name, *args, **kwargs):
        ''' instantiates a plugin of the given name using arguments '''

        if name in self.aliases:
            name = self.aliases[name]
        path = self.find_plugin(name)
        if path is None:
            return None
        if path not in self._module_cache:
            self._module_cache[path] = imp.load_source('.'.join([self.package, name]), path)
        return getattr(self._module_cache[path], self.class_name)(*args, **kwargs)

    def all(self, *args, **kwargs):
        ''' instantiates all plugins with the same arguments '''       

        for i in self._get_paths():
            matches = glob.glob(os.path.join(i, "*.py"))
            matches.sort()
            for path in matches:
                name, ext = os.path.splitext(os.path.basename(path))
                if name.startswith("_"):
                    continue
                if path not in self._module_cache:
                    self._module_cache[path] = imp.load_source('.'.join([self.package, name]), path)
                yield getattr(self._module_cache[path], self.class_name)(*args, **kwargs)

action_loader = PluginLoader(
    'ActionModule',   
    'ansible.runner.action_plugins',
    C.DEFAULT_ACTION_PLUGIN_PATH,
    'action_plugins'
)

callback_loader = PluginLoader(
    'CallbackModule', 
    'ansible.callback_plugins', 
    C.DEFAULT_CALLBACK_PLUGIN_PATH, 
    'callback_plugins'
)

connection_loader = PluginLoader(
    'Connection', 
    'ansible.runner.connection_plugins', 
    C.DEFAULT_CONNECTION_PLUGIN_PATH, 
    'connection_plugins', 
    aliases={'paramiko': 'paramiko_ssh'}
)

module_finder = PluginLoader(
    '', 
    '', 
    C.DEFAULT_MODULE_PATH, 
    'library'
)

lookup_loader = PluginLoader(
    'LookupModule',   
    'ansible.runner.lookup_plugins', 
    C.DEFAULT_LOOKUP_PLUGIN_PATH, 
    'lookup_plugins'
)

vars_loader = PluginLoader(
    'VarsModule', 
    'ansible.inventory.vars_plugins', 
    C.DEFAULT_VARS_PLUGIN_PATH, 
    'vars_plugins'
)

filter_loader = PluginLoader(
    'FilterModule', 
    'ansible.runner.filter_plugins', 
    C.DEFAULT_FILTER_PLUGIN_PATH, 
    'filter_plugins'
)