add hacking check for config options location

This adds a hackign check which raises a pep8 error if a config
option was found in location where it shouldn't be.

Change-Id: I75df3404cc6178aa179e96d75f154e389c3008af

HACKING.rst

@@ -52,6 +52,7 @@ Nova Specific Commandments
 - [N339] Check common raise_feature_not_supported() is used for v2.1 HTTPNotImplemented response.
 - [N340] Check nova.utils.spawn() is used instead of greenthread.spawn() and eventlet.spawn()
 - [N341] contextlib.nested is deprecated
+- [N342] Config options should be in the central location ``nova/conf/``
 
 Creating Unit Tests
 -------------------

nova/hacking/checks.py

@@ -36,6 +36,8 @@ UNDERSCORE_IMPORT_FILES = []
 
 session_check = re.compile(r"\w*def [a-zA-Z0-9].*[(].*session.*[)]")
 cfg_re = re.compile(r".*\scfg\.")
+# Excludes oslo.config OptGroup objects
+cfg_opt_re = re.compile(r".*[\s\[]cfg\.[a-zA-Z]*Opt\(")
 vi_header_re = re.compile(r"^#\s+vim?:.+")
 virt_file_re = re.compile(r"\./nova/(?:tests/)?virt/(\w+)/")
 virt_import_re = re.compile(
@@ -550,6 +552,30 @@ def check_no_contextlib_nested(logical_line, filename):
         yield(0, msg)
 
 
+def check_config_option_in_central_place(logical_line, filename):
+    msg = ("N342: Config options should be in the central location "
+           "'/nova/conf/*'. Do not declare new config options outside "
+           "of that folder.")
+    # That's the correct location
+    if "nova/conf/" in filename:
+        return
+    # TODO(markus_z) This is just temporary until all config options are
+    # moved to the central place. To avoid that a once cleaned up place
+    # introduces new config options, we do a check here. This array will
+    # get quite huge over the time, but will be removed at the end of the
+    # reorganization.
+    # You can add the full path to a module or folder. It's just a substring
+    # check, which makes it flexible enough.
+    cleaned_up = ["nova/console/serial.py",
+                  "nova/cmd/serialproxy.py",
+                  ]
+    if not any(c in filename for c in cleaned_up):
+        return
+
+    if cfg_opt_re.match(logical_line):
+        yield(0, msg)
+
+
 def factory(register):
     register(import_no_db_in_virt)
     register(no_db_session_in_public_api)
@@ -578,3 +604,4 @@ def factory(register):
     register(check_http_not_implemented)
     register(check_no_contextlib_nested)
     register(check_greenthread_spawns)
+    register(check_config_option_in_central_place)

nova/tests/unit/test_hacking.py

@@ -588,3 +588,43 @@ class HackingTestCase(test.NoDBTestCase):
 
         code = "nova.utils.spawn_n(func, arg1, kwarg1=kwarg1)"
         self._assert_has_no_errors(code, checks.check_greenthread_spawns)
+
+    def test_config_option_regex_match(self):
+        def should_match(code):
+            self.assertTrue(checks.cfg_opt_re.match(code))
+
+        def should_not_match(code):
+            self.assertFalse(checks.cfg_opt_re.match(code))
+
+        should_match("opt = cfg.StrOpt('opt_name')")
+        should_match("opt = cfg.IntOpt('opt_name')")
+        should_match("opt = cfg.DictOpt('opt_name')")
+        should_match("opt = cfg.Opt('opt_name')")
+        should_match("opts=[cfg.Opt('opt_name')]")
+        should_match("   cfg.Opt('opt_name')")
+        should_not_match("opt_group = cfg.OptGroup('opt_group_name')")
+
+    def test_check_config_option_in_central_place(self):
+        errors = [(1, 0, "N342")]
+        code = """
+        opts = [
+            cfg.StrOpt('random_opt',
+                       default='foo',
+                       help='I am here to do stuff'),
+            ]
+        """
+        # option at the right place in the tree
+        self._assert_has_no_errors(code,
+                                   checks.check_config_option_in_central_place,
+                                   filename="nova/conf/serial_console.py")
+        # option at a location which is not in scope right now
+        # TODO(markus_z): This is remporary until all config options are
+        # moved to /nova/conf
+        self._assert_has_no_errors(code,
+                                   checks.check_config_option_in_central_place,
+                                   filename="nova/dummy/non_existent.py")
+        # option at the wrong place in the tree
+        self._assert_has_errors(code,
+                                checks.check_config_option_in_central_place,
+                                filename="nova/cmd/serialproxy.py",
+                                expected_errors=errors)