1 files changed, 71 insertions, 6 deletions

diff --git a/synapse/config/_base.py b/synapse/config/_base.py
index 965478d8d5..6ce5cd07fb 100644
--- a/synapse/config/_base.py
+++ b/synapse/config/_base.py
@@ -137,12 +137,42 @@ class Config(object):
             return file_stream.read()
 
     def invoke_all(self, name, *args, **kargs):
+        """Invoke all instance methods with the given name and arguments in the
+        class's MRO.
+
+        Args:
+            name (str): Name of function to invoke
+            *args
+            **kwargs
+
+        Returns:
+            list: The list of the return values from each method called
+        """
         results = []
         for cls in type(self).mro():
             if name in cls.__dict__:
                 results.append(getattr(cls, name)(self, *args, **kargs))
         return results
 
+    @classmethod
+    def invoke_all_static(cls, name, *args, **kargs):
+        """Invoke all static methods with the given name and arguments in the
+        class's MRO.
+
+        Args:
+            name (str): Name of function to invoke
+            *args
+            **kwargs
+
+        Returns:
+            list: The list of the return values from each method called
+        """
+        results = []
+        for c in cls.mro():
+            if name in c.__dict__:
+                results.append(getattr(c, name)(*args, **kargs))
+        return results
+
     def generate_config(
         self,
         config_dir_path,
@@ -202,6 +232,23 @@ class Config(object):
         Returns: Config object.
         """
         config_parser = argparse.ArgumentParser(description=description)
+        cls.add_arguments_to_parser(config_parser)
+        obj, _ = cls.load_config_with_parser(config_parser, argv)
+
+        return obj
+
+    @classmethod
+    def add_arguments_to_parser(cls, config_parser):
+        """Adds all the config flags to an ArgumentParser.
+
+        Doesn't support config-file-generation: used by the worker apps.
+
+        Used for workers where we want to add extra flags/subcommands.
+
+        Args:
+            config_parser (ArgumentParser): App description
+        """
+
         config_parser.add_argument(
             "-c",
             "--config-path",
@@ -219,16 +266,34 @@ class Config(object):
             " Defaults to the directory containing the last config file",
         )
 
-        obj = cls()
+        cls.invoke_all_static("add_arguments", config_parser)
 
-        obj.invoke_all("add_arguments", config_parser)
+    @classmethod
+    def load_config_with_parser(cls, parser, argv):
+        """Parse the commandline and config files with the given parser
+
+        Doesn't support config-file-generation: used by the worker apps.
 
-        config_args = config_parser.parse_args(argv)
+        Used for workers where we want to add extra flags/subcommands.
+
+        Args:
+            parser (ArgumentParser)
+            argv (list[str])
+
+        Returns:
+            tuple[HomeServerConfig, argparse.Namespace]: Returns the parsed
+            config object and the parsed argparse.Namespace object from
+            `parser.parse_args(..)`
+        """
+
+        obj = cls()
+
+        config_args = parser.parse_args(argv)
 
         config_files = find_config_files(search_paths=config_args.config_path)
 
         if not config_files:
-            config_parser.error("Must supply a config file.")
+            parser.error("Must supply a config file.")
 
         if config_args.keys_directory:
             config_dir_path = config_args.keys_directory
@@ -244,7 +309,7 @@ class Config(object):
 
         obj.invoke_all("read_arguments", config_args)
 
-        return obj
+        return obj, config_args
 
     @classmethod
     def load_or_generate_config(cls, description, argv):
@@ -401,7 +466,7 @@ class Config(object):
             formatter_class=argparse.RawDescriptionHelpFormatter,
         )
 
-        obj.invoke_all("add_arguments", parser)
+        obj.invoke_all_static("add_arguments", parser)
         args = parser.parse_args(remaining_args)
 
         config_dict = read_config_files(config_files)