Bug 1415618: Allow specifying extra paths to search for config files mozharness. r=jlund

MozReview-Commit-ID: 3xkUaDwYB6v

--HG--
extra : rebase_source : e80f0f20213e76ee68e62757eab8c788b7d398c6
extra : source : 780f67a36d6d91d4ee35070dc7f8d8c598106929

testing/mozharness/mozharness/base/config.py

@@ -280,6 +280,10 @@ class BaseConfig(object):
             type="string", default=os.getcwd(),
             help="Specify the absolute path of the parent of the working directory"
         )
+        self.config_parser.add_option(
+            "--extra-config-path", action='extend', dest="config_paths",
+            type="string", help="Specify additional paths to search for config files.",
+        )
         self.config_parser.add_option(
             "-c", "--config-file", "--cfg", action="extend", dest="config_files",
             type="string", help="Specify a config file; can be repeated"
@@ -433,6 +437,7 @@ class BaseConfig(object):
         way that self.config is made up.  See
         `mozharness.mozilla.building.buildbase.BuildingConfig` for an example.
         """
+        config_paths = options.config_paths or ['.']
         all_cfg_files_and_dicts = []
         for cf in all_config_files:
             try:
@@ -444,7 +449,9 @@ class BaseConfig(object):
                         (file_path, parse_config_file(file_path, search_path=["."]))
                     )
                 else:
-                    all_cfg_files_and_dicts.append((cf, parse_config_file(cf)))
+                    all_cfg_files_and_dicts.append(
+                        (cf, parse_config_file(cf, search_path=config_paths + [DEFAULT_CONFIG_PATH]))
+                    )
             except Exception:
                 if cf in options.opt_config_files:
                     print(

testing/mozharness/mozharness/mozilla/building/buildbase.py

@@ -399,9 +399,6 @@ class BuildOptionParser(object):
     # TODO add nosetests for this class
     platform = None
     bits = None
-    config_file_search_path = [
-        DEFAULT_CONFIG_PATH,
-    ]
 
     # add to this list and you can automagically do things like
     # --custom-build-variant-cfg asan
@@ -521,9 +518,15 @@ class BuildOptionParser(object):
             # now let's see if we were given a valid pathname
             valid_variant_cfg_path = value
         else:
+            # FIXME: We should actually wait until we have parsed all arguments
+            # before looking at this, otherwise the behavior will depend on the
+            # order of arguments. But that isn't a problem as long as --extra-config-path
+            # is always passed first.
+            extra_config_paths = parser.values.config_paths or []
+            config_paths = extra_config_paths + [DEFAULT_CONFIG_PATH]
             # let's take our prospective_cfg_path and see if we can
             # determine an existing file
-            for path in cls.config_file_search_path:
+            for path in config_paths:
                 if os.path.exists(os.path.join(path, prospective_cfg_path)):
                     # success! we found a config file
                     valid_variant_cfg_path = os.path.join(path,