Add support for XDG-compliant config file

zuul-client will also look by default for the
$XDG_CONFIG_HOME/zuul/client.conf file when looking for user settings.

Change-Id: I60d59fceb1d4e4d767ca9e952a8ecc1630eba0a8

.gitignore

@@ -9,6 +9,7 @@
 .testrepository
 .tox
 .venv
+.vscode
 .coverage
 .stestr
 AUTHORS

doc/source/configuration.rst

@@ -3,15 +3,15 @@
 Configuration
 =============
 
-The web client will look by default for a ``~/.zuul.conf`` file for its
+The web client will look by default for a ``$HOME/.config/zuul/client.conf`` or a ``$HOME/.zuul.conf``
-configuration. The file should consist of a ``[webclient]`` section with at least
+file for its configuration. The file should consist of a ``[webclient]`` section with at least
 the ``url`` attribute set. The optional ``verify_ssl`` can be set to False to
 disable SSL verifications when connecting to Zuul (defaults to True). An
 authentication token can also be stored in the configuration file under the attribute
 ``auth_token`` to avoid passing the token in the clear on the command line.
 A default tenant can also be set with the ``tenant`` attribute.
 
-Here is an example of a ``.zuul.conf`` file that can be used with zuul-client:
+Here is an example of a configuration file that can be used with zuul-client:
 
 .. literalinclude:: /examples/.zuul.conf
    :language: ini

zuulclient/cmd/__init__.py

@@ -16,6 +16,7 @@ import argparse
 import configparser
 import logging
 import os
+from pathlib import Path
 import shutil
 import sys
 import tempfile
@@ -27,6 +28,12 @@ from zuulclient.utils import encrypt_with_openssl
 from zuulclient.utils import formatters
 
 
+_HOME = Path(os.path.expandvars('$HOME'))
+_XDG_CONFIG_HOME = Path(os.environ.get(
+    'XDG_CONFIG_HOME',
+    _HOME / '.config'))
+
+
 class ArgumentException(Exception):
     pass
 
@@ -35,7 +42,10 @@ class ZuulClient():
     app_name = 'zuul-client'
     app_description = 'Zuul User CLI'
     log = logging.getLogger("zuul-client")
-    default_config_locations = ['~/.zuul.conf']
+    default_config_locations = [
+        _XDG_CONFIG_HOME / 'zuul' / 'client.conf',
+        _HOME / '.zuul.conf'
+    ]
 
     def __init__(self):
         self.args = None
@@ -69,7 +79,8 @@ class ZuulClient():
         parser.add_argument('--use-config', dest='zuul_config',
                             required=False,
                             default=None,
-                            help='A predefined configuration in .zuul.conf')
+                            help='A predefined configuration in the '
+                                 'zuul-client configuration file')
         parser.add_argument('--insecure', dest='verify_ssl',
                             required=False,
                             action='store_false',
@@ -153,7 +164,8 @@ class ZuulClient():
                 self.config.read(os.path.expanduser(fp))
                 return
         raise ArgumentException(
-            "Unable to locate config file in %s" % locations)
+            "Unable to locate config "
+            "file in %s" % ', '.join([x.as_posix() for x in locations]))
 
     def setup_logging(self):
         config_args = dict(
@@ -489,7 +501,7 @@ class ZuulClient():
         else:
             raise Exception('Unable to find a way to connect to Zuul, '
                             'provide the "--zuul-url" argument or set up a '
-                            '.zuul.conf file.')
+                            'zuul-client configuration file.')
         server = get_default(self.config,
                              zuul_conf, 'url', None)
         verify = get_default(self.config, zuul_conf,