New module: Add module for manipulating the dconf database (system/dconf) (#23015)
* Implemented dconf module for manipulating and reading the dconf database. * Fixed remote execution for the dconf module when state=present by wrapping the invocation with dbus-launch (dconf requires a running DBus user session). Updated documentation to mention external module dependencies. * Fixed remote execution for the dconf module when state=absent by wrapping the invocation with dbus-launch (dconf requires a running DBus user session). * Updated dconf module implementation to make it more robust: - Detect running D-Bus session, and reuse that one if possible. - If detection fails, try launching process via dbus-run-session to avoid left-over D-Bus processes. - As last resort run dbus-launch, and clean-up after the changes have been made. - Updated documentation to mention new dependencies and to be more explicit about module limitations. * Fixed PEP8 errors reported by ansibot in dconf module. * Updated dconf module implementation: - Fail early if psutil library is not available on the system. - Go through all of user's processes to locate a running D-Bus daemon. - Test potential D-Bus session bus address before deciding to (re)use it. - Added a couple of debug statements. - Updated documentation to include dbus-send as requirement. * Updated dconf module implementation: - Simplified module, removing all code for handling dbus-daemon, as discussed in a community meeting. - Module user must ensure that D-Bus user session is available and specified either via module parameter or environment variable. - Updated documentation for the change. * Updated dconf module implementation: - Add back ability to detect running D-Bus user session. - Fail-back to using dbus-run-session if running session could not be detected. * PEP8 fix for dconf module. * Updated dconf module implementation: - Introduce correct examples for Gnome DE. - Rename existing examples to mark them as Cinnamon-specific. - Use self.module.get_bin_path instead of custom check for dbus-run-session. - Fixed typo in method documentation for DconfPreference.reset().
This commit is contained in:
Branko Majic
Toshio Kuratomi
parent
8badfcd7fe
commit
6ce7448ca4
1 changed files with 384 additions and 0 deletions
384
lib/ansible/modules/system/dconf.py
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384
lib/ansible/modules/system/dconf.py
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#!/usr/bin/python
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# -*- coding: utf-8 -*-
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# (c) 2017, Branko Majic <branko@majic.rs>
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#
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# This file is part of Ansible
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#
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# Ansible is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# Ansible is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with Ansible. If not, see <http://www.gnu.org/licenses/>.
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ANSIBLE_METADATA = {'metadata_version': '1.0',
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'status': ['preview'],
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'supported_by': 'community'}
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DOCUMENTATION = """
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module: dconf
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author:
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- "Branko Majic (@azaghal)"
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short_description: Modify and read dconf database
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description:
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- This module allows modifications and reading of dconf database. The module
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is implemented as a wrapper around dconf tool. Please see the dconf(1) man
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page for more details.
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- Since C(dconf) requires a running D-Bus session to change values, the module
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will try to detect an existing session and reuse it, or run the tool via
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C(dbus-run-session).
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notes:
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- This module depends on C(psutil) Python library (version 4.0.0 and upwards),
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C(dconf), C(dbus-send), and C(dbus-run-session) binaries. Depending on
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distribution you are using, you may need to install additional packages to
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have these available.
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- Detection of existing, running D-Bus session, required to change settings
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via C(dconf), is not 100% reliable due to implementation details of D-Bus
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daemon itself. This might lead to running applications not picking-up
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changes on the fly if options are changed via Ansible and
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C(dbus-run-session).
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- Keep in mind that the C(dconf) CLI tool, which this module wraps around,
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utilises an unusual syntax for the values (GVariant). For example, if you
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wanted to provide a string value, the correct syntax would be
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C(value="'myvalue'") - with single quotes as part of the Ansible parameter
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value.
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- The easiest way to figure out exact syntax/value you need to provide for a
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key is by making the configuration change in application affected by the
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key, and then having a look at value set via commands C(dconf dump
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/path/to/dir/) or C(dconf read /path/to/key).
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version_added: "2.4"
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options:
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key:
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required: true
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description:
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- A dconf key to modify or read from the dconf database.
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value:
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required: false
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description:
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- Value to set for the specified dconf key. Value should be specified in
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GVariant format. Due to complexity of this format, it is best to have a
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look at existing values in the dconf database. Required for
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C(state=present).
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state:
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required: false
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default: present
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choices:
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- read
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- present
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- absent
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description:
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- The action to take upon the key/value.
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"""
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RETURN = """
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value:
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description: value associated with the requested key
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returned: success, state was "read"
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type: string
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sample: "'Default'"
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"""
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EXAMPLES = """
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- name: Configure available keyboard layouts in Gnome
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dconf:
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key: "/org/gnome/desktop/input-sources/sources"
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value: "[('xkb', 'us'), ('xkb', 'se')]"
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state: present
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- name: Read currently available keyboard layouts in Gnome
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dconf:
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key: "/org/gnome/desktop/input-sources/sources"
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state: read
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register: keyboard_layouts
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- name: Reset the available keyboard layouts in Gnome
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dconf:
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key: "/org/gnome/desktop/input-sources/sources"
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state: absent
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- name: Configure available keyboard layouts in Cinnamon
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dconf:
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key: "/org/gnome/libgnomekbd/keyboard/layouts"
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value: "['us', 'se']"
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state: present
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- name: Read currently available keyboard layouts in Cinnamon
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dconf:
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key: "/org/gnome/libgnomekbd/keyboard/layouts"
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state: read
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register: keyboard_layouts
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- name: Reset the available keyboard layouts in Cinnamon
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dconf:
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key: "/org/gnome/libgnomekbd/keyboard/layouts"
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state: absent
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- name: Disable desktop effects in Cinnamon
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dconf:
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key: "/org/cinnamon/desktop-effects"
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value: "false"
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state: present
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"""
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import os
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try:
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import psutil
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psutil_found = True
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except ImportError:
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psutil_found = False
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from ansible.module_utils.basic import AnsibleModule
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class DBusWrapper(object):
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"""
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Helper class that can be used for running a command with a working D-Bus
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session.
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If possible, command will be run against an existing D-Bus session,
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otherwise the session will be spawned via dbus-run-session.
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Example usage:
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dbus_wrapper = DBusWrapper(ansible_module)
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dbus_wrapper.run_command(["printenv", "DBUS_SESSION_BUS_ADDRESS"])
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"""
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def __init__(self, module):
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"""
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Initialises an instance of the class.
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:param module: Ansible module instance used to signal failures and run commands.
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:type module: AnsibleModule
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"""
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# Store passed-in arguments and set-up some defaults.
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self.module = module
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# Try to extract existing D-Bus session address.
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self.dbus_session_bus_address = self._get_existing_dbus_session()
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# If no existing D-Bus session was detected, check if dbus-run-session
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# is available.
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if self.dbus_session_bus_address is None:
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self.module.get_bin_path('dbus-run-session', required=True)
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def _get_existing_dbus_session(self):
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"""
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Detects and returns an existing D-Bus session bus address.
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:returns: string -- D-Bus session bus address. If a running D-Bus session was not detected, returns None.
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"""
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# We'll be checking the processes of current user only.
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uid = os.getuid()
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# Go through all the pids for this user, try to extract the D-Bus
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# session bus address from environment, and ensure it is possible to
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# connect to it.
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self.module.debug("Trying to detect existing D-Bus user session for user: %d" % uid)
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for pid in psutil.pids():
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process = psutil.Process(pid)
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process_real_uid, _, _ = process.uids()
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try:
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if process_real_uid == uid and 'DBUS_SESSION_BUS_ADDRESS' in process.environ():
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dbus_session_bus_address_candidate = process.environ()['DBUS_SESSION_BUS_ADDRESS']
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self.module.debug("Found D-Bus user session candidate at address: %s" % dbus_session_bus_address_candidate)
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command = ['dbus-send', '--address=%s' % dbus_session_bus_address_candidate, '--type=signal', '/', 'com.example.test']
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rc, _, _ = self.module.run_command(command)
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if rc == 0:
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self.module.debug("Verified D-Bus user session candidate as usable at address: %s" % dbus_session_bus_address_candidate)
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return dbus_session_bus_address_candidate
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# This can happen with things like SSH sessions etc.
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except psutil.AccessDenied:
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pass
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self.module.debug("Failed to find running D-Bus user session, will use dbus-run-session")
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return None
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def run_command(self, command):
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"""
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Runs the specified command within a functional D-Bus session. Command is
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effectively passed-on to AnsibleModule.run_command() method, with
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modification for using dbus-run-session if necessary.
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:param command: Command to run, including parameters. Each element of the list should be a string.
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:type module: list
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:returns: tuple(result_code, standard_output, standard_error) -- Result code, standard output, and standard error from running the command.
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"""
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if self.dbus_session_bus_address is None:
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self.module.debug("Using dbus-run-session wrapper for running commands.")
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command = ['dbus-run-session'] + command
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rc, out, err = self.module.run_command(command)
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if self.dbus_session_bus_address is None and rc == 127:
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self.module.fail_json("Failed to run passed-in command, dbus-run-session faced an internal erorr: %s" % err)
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else:
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extra_environment = {'DBUS_SESSION_BUS_ADDRESS': self.dbus_session_bus_address}
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rc, out, err = self.module.run_command(command, environ_update=extra_environment)
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return rc, out, err
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class DconfPreference(object):
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def __init__(self, module, check_mode=False):
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"""
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Initialises instance of the class.
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:param module: Ansible module instance used to signal failures and run commands.
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:type module: AnsibleModule
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:param check_mode: Specify whether to only check if a change should be made or if to actually make a change.
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:type check_mode: bool
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"""
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self.module = module
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self.check_mode = check_mode
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def read(self, key):
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"""
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Retrieves current value associated with the dconf key.
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If an error occurs, a call will be made to AnsibleModule.fail_json.
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:returns: string -- Value assigned to the provided key. If the value is not set for specified key, returns None.
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"""
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command = ["dconf", "read", key]
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rc, out, err = self.module.run_command(command)
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if rc != 0:
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self.module.fail_json(msg='dconf failed while reading the value with error: %s' % err)
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if out == '':
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value = None
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else:
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value = out.rstrip('\n')
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return value
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def write(self, key, value):
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"""
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Writes the value for specified key.
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If an error occurs, a call will be made to AnsibleModule.fail_json.
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:param key: dconf key for which the value should be set. Should be a full path.
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:type key: str
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:param value: Value to set for the specified dconf key. Should be specified in GVariant format.
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:type value: str
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:returns: bool -- True if a change was made, False if no change was required.
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"""
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# If no change is needed (or won't be done due to check_mode), notify
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# caller straight away.
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if value == self.read(key):
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return False
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elif self.check_mode:
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return True
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# Set-up command to run. Since DBus is needed for write operation, wrap
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# dconf command dbus-launch.
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command = ["dconf", "write", key, value]
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# Run the command and fetch standard return code, stdout, and stderr.
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dbus_wrapper = DBusWrapper(self.module)
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rc, out, err = dbus_wrapper.run_command(command)
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if rc != 0:
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self.module.fail_json(msg='dconf failed while write the value with error: %s' % err)
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# Value was changed.
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return True
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def reset(self, key):
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"""
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Returns value for the specified key (removes it from user configuration).
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If an error occurs, a call will be made to AnsibleModule.fail_json.
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:param key: dconf key to reset. Should be a full path.
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:type key: str
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:returns: bool -- True if a change was made, False if no change was required.
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"""
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# Read the current value first.
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current_value = self.read(key)
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# No change was needed, key is not set at all, or just notify user if we
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# are in check mode.
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if current_value is None:
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return False
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elif self.check_mode:
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return True
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# Set-up command to run. Since DBus is needed for reset operation, wrap
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# dconf command dbus-launch.
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command = ["dconf", "reset", key]
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# Run the command and fetch standard return code, stdout, and stderr.
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dbus_wrapper = DBusWrapper(self.module)
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rc, out, err = dbus_wrapper.run_command(command)
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if rc != 0:
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self.module.fail_json(msg='dconf failed while reseting the value with error: %s' % err)
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# Value was changed.
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return True
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def main():
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# Setup the Ansible module
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module = AnsibleModule(
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argument_spec=dict(
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state=dict(default='present', choices=['present', 'absent', 'read']),
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key=dict(required=True, type='str'),
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value=dict(required=False, default=None, type='str'),
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),
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supports_check_mode=True
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)
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if not psutil_found:
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module.fail_json(msg="Python module psutil is required on managed machine")
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# If present state was specified, value must be provided.
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if module.params['state'] == 'present' and module.params['value'] is None:
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module.fail_json(msg='State "present" requires "value" to be set.')
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# Create wrapper instance.
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dconf = DconfPreference(module, module.check_mode)
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# Process based on different states.
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if module.params['state'] == 'read':
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value = dconf.read(module.params['key'])
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module.exit_json(changed=False, value=value)
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elif module.params['state'] == 'present':
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changed = dconf.write(module.params['key'], module.params['value'])
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module.exit_json(changed=changed)
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elif module.params['state'] == 'absent':
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changed = dconf.reset(module.params['key'])
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module.exit_json(changed=changed)
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if __name__ == '__main__':
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main()
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