Add a config file for perspective servers

synapse/config/_base.py

@@ -77,6 +77,17 @@ class Config(object):
         with open(file_path) as file_stream:
             return file_stream.read()
 
+    @classmethod
+    def read_yaml_file(cls, file_path, config_name):
+        cls.check_file(file_path, config_name)
+        with open(file_path) as file_stream:
+            try:
+                return yaml.load(file_stream)
+            except Exception as e:
+                raise ConfigError(
+                    "Error parsing yaml in file %r: " % (file_path,), e
+                )
+
     @staticmethod
     def default_path(name):
         return os.path.abspath(os.path.join(os.path.curdir, name))

synapse/config/key.py

@@ -27,6 +27,9 @@ class KeyConfig(Config):
             args.old_signing_key_path
         )
         self.key_refresh_interval = args.key_refresh_interval
+        self.perspectives = self.read_perspectives(
+            args.perspectives_config_path
+        )
 
     @classmethod
     def add_arguments(cls, parser):
@@ -45,6 +48,15 @@ class KeyConfig(Config):
                                     " Used to set the exipiry in /key/v2/."
                                     " Controls how frequently servers will"
                                     " query what keys are still valid")
+        key_group.add_argument("--perspectives-config-path",
+                               help="The trusted servers to download signing"
+                                    " keys from")
+
+    def read_perspectives(self, perspectives_config_path):
+        servers = self.read_yaml_file(
+            perspectives_config_path, "perspectives_config_path"
+        )
+        return servers
 
     def read_signing_key(self, signing_key_path):
         signing_keys = self.read_file(signing_key_path, "signing_key")
@@ -108,3 +120,10 @@ class KeyConfig(Config):
         if not os.path.exists(args.old_signing_key_path):
             with open(args.old_signing_key_path, "w"):
                 pass
+
+        if not args.perspectives_config_path:
+            args.perspectives_config_path = base_key_name + ".perspectives"
+
+        if not os.path.exists(args.perspectives_config_path):
+            with open(args.perspectives_config_path, "w") as perspectives_file:
+                perspectives_file.write("@@@")