3 files changed, 11 insertions, 9 deletions
diff --git a/synapse/logging/_structured.py b/synapse/logging/_structured.py
index 0367d6dfc4..3220e985a9 100644
--- a/synapse/logging/_structured.py
+++ b/synapse/logging/_structured.py
@@ -18,6 +18,7 @@ import os.path
 import sys
 import typing
 import warnings
+from typing import List
 
 import attr
 from constantly import NamedConstant, Names, ValueConstant, Values
@@ -33,7 +34,6 @@ from twisted.logger import (
     LogLevelFilterPredicate,
     LogPublisher,
     eventAsText,
-    globalLogBeginner,
     jsonFileLogObserver,
 )
 
@@ -134,7 +134,7 @@ class PythonStdlibToTwistedLogger(logging.Handler):
         )
 
 
-def SynapseFileLogObserver(outFile: typing.io.TextIO) -> FileLogObserver:
+def SynapseFileLogObserver(outFile: typing.IO[str]) -> FileLogObserver:
     """
     A log observer that formats events like the traditional log formatter and
     sends them to `outFile`.
@@ -265,7 +265,7 @@ def setup_structured_logging(
     hs,
     config,
     log_config: dict,
-    logBeginner: LogBeginner = globalLogBeginner,
+    logBeginner: LogBeginner,
     redirect_stdlib_logging: bool = True,
 ) -> LogPublisher:
     """
@@ -286,7 +286,7 @@ def setup_structured_logging(
     if "drains" not in log_config:
         raise ConfigError("The logging configuration requires a list of drains.")
 
-    observers = []
+    observers = []  # type: List[ILogObserver]
 
     for observer in parse_drain_configs(log_config["drains"]):
         # Pipe drains
diff --git a/synapse/logging/_terse_json.py b/synapse/logging/_terse_json.py
index 7f1e8f23fe..0ebbde06f2 100644
--- a/synapse/logging/_terse_json.py
+++ b/synapse/logging/_terse_json.py
@@ -21,10 +21,11 @@ import sys
 from collections import deque
 from ipaddress import IPv4Address, IPv6Address, ip_address
 from math import floor
-from typing.io import TextIO
+from typing import IO
 
 import attr
 from simplejson import dumps
+from zope.interface import implementer
 
 from twisted.application.internet import ClientService
 from twisted.internet.endpoints import (
@@ -33,7 +34,7 @@ from twisted.internet.endpoints import (
     TCP6ClientEndpoint,
 )
 from twisted.internet.protocol import Factory, Protocol
-from twisted.logger import FileLogObserver, Logger
+from twisted.logger import FileLogObserver, ILogObserver, Logger
 from twisted.python.failure import Failure
 
 
@@ -129,7 +130,7 @@ def flatten_event(event: dict, metadata: dict, include_time: bool = False):
     return new_event
 
 
-def TerseJSONToConsoleLogObserver(outFile: TextIO, metadata: dict) -> FileLogObserver:
+def TerseJSONToConsoleLogObserver(outFile: IO[str], metadata: dict) -> FileLogObserver:
     """
     A log observer that formats events to a flattened JSON representation.
 
@@ -146,6 +147,7 @@ def TerseJSONToConsoleLogObserver(outFile: TextIO, metadata: dict) -> FileLogObs
 
 
 @attr.s
+@implementer(ILogObserver)
 class TerseJSONToTCPLogObserver(object):
     """
     An IObserver that writes JSON logs to a TCP target.
diff --git a/synapse/logging/opentracing.py b/synapse/logging/opentracing.py
index 7246253018..308a27213b 100644
--- a/synapse/logging/opentracing.py
+++ b/synapse/logging/opentracing.py
@@ -223,8 +223,8 @@ try:
     from jaeger_client import Config as JaegerConfig
     from synapse.logging.scopecontextmanager import LogContextScopeManager
 except ImportError:
-    JaegerConfig = None
-    LogContextScopeManager = None
+    JaegerConfig = None  # type: ignore
+    LogContextScopeManager = None  # type: ignore
 
 
 logger = logging.getLogger(__name__)