Config: Allow a user-global configuration file

Instead of just looking for `.yamllint` in the current working
directory, also look for `~/.config/yamllint/config` (using
`$XDG_CONFIG_HOME` or `$HOME`, see [1] and [2] for information).

[1]: https://specifications.freedesktop.org/basedir-spec/basedir-spec-0.6.html
[2]: https://wiki.archlinux.org/index.php/XDG_Base_Directory_support

Closes: #6

README.rst

@@ -82,7 +82,7 @@ Usage
  yamllint -d relaxed file.yaml
 
  # Use a custom lint configuration
- yamllint -c ~/myconfig file.yml
+ yamllint -c /path/to/myconfig file-to-lint.yaml
 
 .. code:: bash
 

docs/configuration.rst

@@ -5,12 +5,20 @@ yamllint uses a set of *rules* to check sources files for problems. Each rule is
 independent from the others, and can be enabled, disabled or tweaked. All these
 settings can be gathered in a configuration file.
 
-To use a custom configuration file, either name it ``.yamllint`` in your working
-directory, or use the ``-c`` option:
+To use a custom configuration file, use the ``-c`` option:
 
 .. code:: bash
 
- yamllint -c ~/myconfig file.yaml
+ yamllint -c /path/to/myconfig file-to-lint.yaml
+
+If ``-c`` is not provided, yamllint will look for a configuration file in the
+following locations (by order of preference):
+
+- ``.yamllint`` in the current working directory
+- ``$XDG_CONFIG_HOME/yamllint/config``
+- ``$HOME/.config/yamllint/config``
+
+Finally if no config file is found, the default configuration is applied.
 
 Default configuration
 ---------------------

tests/test_cli.py

@@ -153,6 +153,49 @@ class CommandLineTestCase(unittest.TestCase):
         self.assertEqual(out, '')
         self.assertRegexpMatches(err, r'^invalid config: not a dict')
 
+    def test_run_with_config_file(self):
+        with open(os.path.join(self.wd, 'config'), 'w') as f:
+            f.write('rules: {trailing-spaces: disable}')
+
+        with self.assertRaises(SystemExit) as ctx:
+            cli.run(('-c', f.name, os.path.join(self.wd, 'a.yaml')))
+        self.assertEqual(ctx.exception.code, 0)
+
+        with open(os.path.join(self.wd, 'config'), 'w') as f:
+            f.write('rules: {trailing-spaces: enable}')
+
+        with self.assertRaises(SystemExit) as ctx:
+            cli.run(('-c', f.name, os.path.join(self.wd, 'a.yaml')))
+        self.assertEqual(ctx.exception.code, 1)
+
+    def test_run_with_user_global_config_file(self):
+        home = os.path.join(self.wd, 'fake-home')
+        os.mkdir(home)
+        dir = os.path.join(home, '.config')
+        os.mkdir(dir)
+        dir = os.path.join(dir, 'yamllint')
+        os.mkdir(dir)
+        config = os.path.join(dir, 'config')
+
+        temp = os.environ['HOME']
+        os.environ['HOME'] = home
+
+        with open(config, 'w') as f:
+            f.write('rules: {trailing-spaces: disable}')
+
+        with self.assertRaises(SystemExit) as ctx:
+            cli.run((os.path.join(self.wd, 'a.yaml'), ))
+        self.assertEqual(ctx.exception.code, 0)
+
+        with open(config, 'w') as f:
+            f.write('rules: {trailing-spaces: enable}')
+
+        with self.assertRaises(SystemExit) as ctx:
+            cli.run((os.path.join(self.wd, 'a.yaml'), ))
+        self.assertEqual(ctx.exception.code, 1)
+
+        os.environ['HOME'] = temp
+
     def test_run_version(self):
         sys.stdout, sys.stderr = StringIO(), StringIO()
         with self.assertRaises(SystemExit) as ctx:

yamllint/cli.py

@@ -86,6 +86,15 @@ def run(argv=None):
               'simultaneously.', file=sys.stderr)
         sys.exit(-1)
 
+    # User-global config is supposed to be in ~/.config/yamllint/config
+    user_global_config = None
+    if 'XDG_CONFIG_HOME' in os.environ:
+        user_global_config = os.path.join(
+            os.environ['XDG_CONFIG_HOME'], 'yamllint', 'config')
+    elif 'HOME' in os.environ:
+        user_global_config = os.path.join(
+            os.environ['HOME'], '.config', 'yamllint', 'config')
+
     try:
         if args.config_data is not None:
             if args.config_data != '' and ':' not in args.config_data:
@@ -95,6 +104,8 @@ def run(argv=None):
             conf = YamlLintConfig(file=args.config_file)
         elif os.path.isfile('.yamllint'):
             conf = YamlLintConfig(file='.yamllint')
+        elif user_global_config and os.path.isfile(user_global_config):
+            conf = YamlLintConfig(file=user_global_config)
         else:
             conf = YamlLintConfig('extends: default')
     except YamlLintConfigError as e: