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#!/usr/bin/python
# -*- coding: utf-8 -*-
# (c) 2017, Branko Majic <branko@majic.rs>
# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
from __future__ import absolute_import, division, print_function
__metaclass__ = type
ANSIBLE_METADATA = {'metadata_version': '1.1',
'status': ['preview'],
'supported_by': 'community'}
DOCUMENTATION = """
module: dconf
author:
- "Branko Majic (@azaghal)"
short_description: Modify and read dconf database
description:
- This module allows modifications and reading of dconf database. The module
is implemented as a wrapper around dconf tool. Please see the dconf(1) man
page for more details.
- Since C(dconf) requires a running D-Bus session to change values, the module
will try to detect an existing session and reuse it, or run the tool via
C(dbus-run-session).
notes:
- This module depends on C(psutil) Python library (version 4.0.0 and upwards),
C(dconf), C(dbus-send), and C(dbus-run-session) binaries. Depending on
distribution you are using, you may need to install additional packages to
have these available.
- Detection of existing, running D-Bus session, required to change settings
via C(dconf), is not 100% reliable due to implementation details of D-Bus
daemon itself. This might lead to running applications not picking-up
changes on the fly if options are changed via Ansible and
C(dbus-run-session).
- Keep in mind that the C(dconf) CLI tool, which this module wraps around,
utilises an unusual syntax for the values (GVariant). For example, if you
wanted to provide a string value, the correct syntax would be
C(value="'myvalue'") - with single quotes as part of the Ansible parameter
value.
- The easiest way to figure out exact syntax/value you need to provide for a
key is by making the configuration change in application affected by the
key, and then having a look at value set via commands C(dconf dump
/path/to/dir/) or C(dconf read /path/to/key).
version_added: "2.4"
options:
key:
required: true
description:
- A dconf key to modify or read from the dconf database.
value:
required: false
description:
- Value to set for the specified dconf key. Value should be specified in
GVariant format. Due to complexity of this format, it is best to have a
look at existing values in the dconf database. Required for
C(state=present).
state:
required: false
default: present
choices:
- read
- present
- absent
description:
- The action to take upon the key/value.
"""
RETURN = """
value:
description: value associated with the requested key
returned: success, state was "read"
type: str
sample: "'Default'"
"""
EXAMPLES = """
- name: Configure available keyboard layouts in Gnome
dconf:
key: "/org/gnome/desktop/input-sources/sources"
value: "[('xkb', 'us'), ('xkb', 'se')]"
state: present
- name: Read currently available keyboard layouts in Gnome
dconf:
key: "/org/gnome/desktop/input-sources/sources"
state: read
register: keyboard_layouts
- name: Reset the available keyboard layouts in Gnome
dconf:
key: "/org/gnome/desktop/input-sources/sources"
state: absent
- name: Configure available keyboard layouts in Cinnamon
dconf:
key: "/org/gnome/libgnomekbd/keyboard/layouts"
value: "['us', 'se']"
state: present
- name: Read currently available keyboard layouts in Cinnamon
dconf:
key: "/org/gnome/libgnomekbd/keyboard/layouts"
state: read
register: keyboard_layouts
- name: Reset the available keyboard layouts in Cinnamon
dconf:
key: "/org/gnome/libgnomekbd/keyboard/layouts"
state: absent
- name: Disable desktop effects in Cinnamon
dconf:
key: "/org/cinnamon/desktop-effects"
value: "false"
state: present
"""
import os
try:
import psutil
psutil_found = True
except ImportError:
psutil_found = False
from ansible.module_utils.basic import AnsibleModule
class DBusWrapper(object):
"""
Helper class that can be used for running a command with a working D-Bus
session.
If possible, command will be run against an existing D-Bus session,
otherwise the session will be spawned via dbus-run-session.
Example usage:
dbus_wrapper = DBusWrapper(ansible_module)
dbus_wrapper.run_command(["printenv", "DBUS_SESSION_BUS_ADDRESS"])
"""
def __init__(self, module):
"""
Initialises an instance of the class.
:param module: Ansible module instance used to signal failures and run commands.
:type module: AnsibleModule
"""
# Store passed-in arguments and set-up some defaults.
self.module = module
# Try to extract existing D-Bus session address.
self.dbus_session_bus_address = self._get_existing_dbus_session()
# If no existing D-Bus session was detected, check if dbus-run-session
# is available.
if self.dbus_session_bus_address is None:
self.module.get_bin_path('dbus-run-session', required=True)
def _get_existing_dbus_session(self):
"""
Detects and returns an existing D-Bus session bus address.
:returns: string -- D-Bus session bus address. If a running D-Bus session was not detected, returns None.
"""
# We'll be checking the processes of current user only.
uid = os.getuid()
# Go through all the pids for this user, try to extract the D-Bus
# session bus address from environment, and ensure it is possible to
# connect to it.
self.module.debug("Trying to detect existing D-Bus user session for user: %d" % uid)
for pid in psutil.pids():
process = psutil.Process(pid)
process_real_uid, _, _ = process.uids()
try:
if process_real_uid == uid and 'DBUS_SESSION_BUS_ADDRESS' in process.environ():
dbus_session_bus_address_candidate = process.environ()['DBUS_SESSION_BUS_ADDRESS']
self.module.debug("Found D-Bus user session candidate at address: %s" % dbus_session_bus_address_candidate)
command = ['dbus-send', '--address=%s' % dbus_session_bus_address_candidate, '--type=signal', '/', 'com.example.test']
rc, _, _ = self.module.run_command(command)
if rc == 0:
self.module.debug("Verified D-Bus user session candidate as usable at address: %s" % dbus_session_bus_address_candidate)
return dbus_session_bus_address_candidate
# This can happen with things like SSH sessions etc.
except psutil.AccessDenied:
pass
self.module.debug("Failed to find running D-Bus user session, will use dbus-run-session")
return None
def run_command(self, command):
"""
Runs the specified command within a functional D-Bus session. Command is
effectively passed-on to AnsibleModule.run_command() method, with
modification for using dbus-run-session if necessary.
:param command: Command to run, including parameters. Each element of the list should be a string.
:type module: list
:returns: tuple(result_code, standard_output, standard_error) -- Result code, standard output, and standard error from running the command.
"""
if self.dbus_session_bus_address is None:
self.module.debug("Using dbus-run-session wrapper for running commands.")
command = ['dbus-run-session'] + command
rc, out, err = self.module.run_command(command)
if self.dbus_session_bus_address is None and rc == 127:
self.module.fail_json(msg="Failed to run passed-in command, dbus-run-session faced an internal error: %s" % err)
else:
extra_environment = {'DBUS_SESSION_BUS_ADDRESS': self.dbus_session_bus_address}
rc, out, err = self.module.run_command(command, environ_update=extra_environment)
return rc, out, err
class DconfPreference(object):
def __init__(self, module, check_mode=False):
"""
Initialises instance of the class.
:param module: Ansible module instance used to signal failures and run commands.
:type module: AnsibleModule
:param check_mode: Specify whether to only check if a change should be made or if to actually make a change.
:type check_mode: bool
"""
self.module = module
self.check_mode = check_mode
def read(self, key):
"""
Retrieves current value associated with the dconf key.
If an error occurs, a call will be made to AnsibleModule.fail_json.
:returns: string -- Value assigned to the provided key. If the value is not set for specified key, returns None.
"""
command = ["dconf", "read", key]
rc, out, err = self.module.run_command(command)
if rc != 0:
self.module.fail_json(msg='dconf failed while reading the value with error: %s' % err)
if out == '':
value = None
else:
value = out.rstrip('\n')
return value
def write(self, key, value):
"""
Writes the value for specified key.
If an error occurs, a call will be made to AnsibleModule.fail_json.
:param key: dconf key for which the value should be set. Should be a full path.
:type key: str
:param value: Value to set for the specified dconf key. Should be specified in GVariant format.
:type value: str
:returns: bool -- True if a change was made, False if no change was required.
"""
# If no change is needed (or won't be done due to check_mode), notify
# caller straight away.
if value == self.read(key):
return False
elif self.check_mode:
return True
# Set-up command to run. Since DBus is needed for write operation, wrap
# dconf command dbus-launch.
command = ["dconf", "write", key, value]
# Run the command and fetch standard return code, stdout, and stderr.
dbus_wrapper = DBusWrapper(self.module)
rc, out, err = dbus_wrapper.run_command(command)
if rc != 0:
self.module.fail_json(msg='dconf failed while write the value with error: %s' % err)
# Value was changed.
return True
def reset(self, key):
"""
Returns value for the specified key (removes it from user configuration).
If an error occurs, a call will be made to AnsibleModule.fail_json.
:param key: dconf key to reset. Should be a full path.
:type key: str
:returns: bool -- True if a change was made, False if no change was required.
"""
# Read the current value first.
current_value = self.read(key)
# No change was needed, key is not set at all, or just notify user if we
# are in check mode.
if current_value is None:
return False
elif self.check_mode:
return True
# Set-up command to run. Since DBus is needed for reset operation, wrap
# dconf command dbus-launch.
command = ["dconf", "reset", key]
# Run the command and fetch standard return code, stdout, and stderr.
dbus_wrapper = DBusWrapper(self.module)
rc, out, err = dbus_wrapper.run_command(command)
if rc != 0:
self.module.fail_json(msg='dconf failed while reseting the value with error: %s' % err)
# Value was changed.
return True
def main():
# Setup the Ansible module
module = AnsibleModule(
argument_spec=dict(
state=dict(default='present', choices=['present', 'absent', 'read']),
key=dict(required=True, type='str'),
value=dict(required=False, default=None, type='str'),
),
supports_check_mode=True
)
if not psutil_found:
module.fail_json(msg="Python module psutil is required on managed machine")
# If present state was specified, value must be provided.
if module.params['state'] == 'present' and module.params['value'] is None:
module.fail_json(msg='State "present" requires "value" to be set.')
# Create wrapper instance.
dconf = DconfPreference(module, module.check_mode)
# Process based on different states.
if module.params['state'] == 'read':
value = dconf.read(module.params['key'])
module.exit_json(changed=False, value=value)
elif module.params['state'] == 'present':
changed = dconf.write(module.params['key'], module.params['value'])
module.exit_json(changed=changed)
elif module.params['state'] == 'absent':
changed = dconf.reset(module.params['key'])
module.exit_json(changed=changed)
if __name__ == '__main__':
main()
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