5 files changed, 28 insertions, 19 deletions
diff --git a/changelog.d/11480.misc b/changelog.d/11480.misc
new file mode 100644
index 0000000000..aadc938b2b
--- /dev/null
+++ b/changelog.d/11480.misc
@@ -0,0 +1 @@
+Add missing type hints to `synapse.config` module.
diff --git a/synapse/config/key.py b/synapse/config/key.py
index 035ee2416b..ee83c6c06b 100644
--- a/synapse/config/key.py
+++ b/synapse/config/key.py
@@ -16,12 +16,14 @@
 import hashlib
 import logging
 import os
-from typing import Any, Dict
+from typing import Any, Dict, Iterator, List, Optional
 
 import attr
 import jsonschema
 from signedjson.key import (
     NACL_ED25519,
+    SigningKey,
+    VerifyKey,
     decode_signing_key_base64,
     decode_verify_key_bytes,
     generate_signing_key,
@@ -31,6 +33,7 @@ from signedjson.key import (
 )
 from unpaddedbase64 import decode_base64
 
+from synapse.types import JsonDict
 from synapse.util.stringutils import random_string, random_string_with_symbols
 
 from ._base import Config, ConfigError
@@ -81,14 +84,13 @@ To suppress this warning and continue using 'matrix.org', admins should set
 logger = logging.getLogger(__name__)
 
 
-@attr.s
+@attr.s(slots=True, auto_attribs=True)
 class TrustedKeyServer:
-    # string: name of the server.
-    server_name = attr.ib()
+    # name of the server.
+    server_name: str
 
-    # dict[str,VerifyKey]|None: map from key id to key object, or None to disable
-    # signature verification.
-    verify_keys = attr.ib(default=None)
+    # map from key id to key object, or None to disable signature verification.
+    verify_keys: Optional[Dict[str, VerifyKey]] = None
 
 
 class KeyConfig(Config):
@@ -279,15 +281,15 @@ class KeyConfig(Config):
             % locals()
         )
 
-    def read_signing_keys(self, signing_key_path, name):
+    def read_signing_keys(self, signing_key_path: str, name: str) -> List[SigningKey]:
         """Read the signing keys in the given path.
 
         Args:
-            signing_key_path (str)
-            name (str): Associated config key name
+            signing_key_path
+            name: Associated config key name
 
         Returns:
-            list[SigningKey]
+            The signing keys read from the given path.
         """
 
         signing_keys = self.read_file(signing_key_path, name)
@@ -296,7 +298,9 @@ class KeyConfig(Config):
         except Exception as e:
             raise ConfigError("Error reading %s: %s" % (name, str(e)))
 
-    def read_old_signing_keys(self, old_signing_keys):
+    def read_old_signing_keys(
+        self, old_signing_keys: Optional[JsonDict]
+    ) -> Dict[str, VerifyKey]:
         if old_signing_keys is None:
             return {}
         keys = {}
@@ -340,7 +344,7 @@ class KeyConfig(Config):
                     write_signing_keys(signing_key_file, (key,))
 
 
-def _perspectives_to_key_servers(config):
+def _perspectives_to_key_servers(config: JsonDict) -> Iterator[JsonDict]:
     """Convert old-style 'perspectives' configs into new-style 'trusted_key_servers'
 
     Returns an iterable of entries to add to trusted_key_servers.
@@ -402,7 +406,9 @@ TRUSTED_KEY_SERVERS_SCHEMA = {
 }
 
 
-def _parse_key_servers(key_servers, federation_verify_certificates):
+def _parse_key_servers(
+    key_servers: List[Any], federation_verify_certificates: bool
+) -> Iterator[TrustedKeyServer]:
     try:
         jsonschema.validate(key_servers, TRUSTED_KEY_SERVERS_SCHEMA)
     except jsonschema.ValidationError as e:
@@ -444,7 +450,7 @@ def _parse_key_servers(key_servers, federation_verify_certificates):
         yield result
 
 
-def _assert_keyserver_has_verify_keys(trusted_key_server):
+def _assert_keyserver_has_verify_keys(trusted_key_server: TrustedKeyServer) -> None:
     if not trusted_key_server.verify_keys:
         raise ConfigError(INSECURE_NOTARY_ERROR)
 
diff --git a/synapse/config/metrics.py b/synapse/config/metrics.py
index 7ac82edb0e..1cc26e7578 100644
--- a/synapse/config/metrics.py
+++ b/synapse/config/metrics.py
@@ -22,10 +22,12 @@ from ._base import Config, ConfigError
 
 @attr.s
 class MetricsFlags:
-    known_servers = attr.ib(default=False, validator=attr.validators.instance_of(bool))
+    known_servers: bool = attr.ib(
+        default=False, validator=attr.validators.instance_of(bool)
+    )
 
     @classmethod
-    def all_off(cls):
+    def all_off(cls) -> "MetricsFlags":
         """
         Instantiate the flags with all options set to off.
         """
diff --git a/synapse/config/server.py b/synapse/config/server.py
index ba5b954263..1de2dea9b0 100644
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -1257,7 +1257,7 @@ class ServerConfig(Config):
             help="Turn on the twisted telnet manhole service on the given port.",
         )
 
-    def read_gc_intervals(self, durations) -> Optional[Tuple[float, float, float]]:
+    def read_gc_intervals(self, durations: Any) -> Optional[Tuple[float, float, float]]:
         """Reads the three durations for the GC min interval option, returning seconds."""
         if durations is None:
             return None
diff --git a/synapse/config/tls.py b/synapse/config/tls.py
index 4ca111618f..ffb316e4c0 100644
--- a/synapse/config/tls.py
+++ b/synapse/config/tls.py
@@ -132,7 +132,7 @@ class TlsConfig(Config):
         self.tls_certificate: Optional[crypto.X509] = None
         self.tls_private_key: Optional[crypto.PKey] = None
 
-    def read_certificate_from_disk(self):
+    def read_certificate_from_disk(self) -> None:
         """
         Read the certificates and private key from disk.
         """