1 files changed, 10 insertions, 27 deletions
diff --git a/synapse/config/workers.py b/synapse/config/workers.py
index f23e42cdf9..c784a71508 100644
--- a/synapse/config/workers.py
+++ b/synapse/config/workers.py
@@ -13,24 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from typing import List, Union
-
 import attr
 
 from ._base import Config, ConfigError, ShardedWorkerHandlingConfig
 from .server import ListenerConfig, parse_listener_def
 
 
-def _instance_to_list_converter(obj: Union[str, List[str]]) -> List[str]:
-    """Helper for allowing parsing a string or list of strings to a config
-    option expecting a list of strings.
-    """
-
-    if isinstance(obj, str):
-        return [obj]
-    return obj
-
-
 @attr.s
 class InstanceLocationConfig:
     """The host and port to talk to an instance via HTTP replication.
@@ -45,13 +33,11 @@ class WriterLocations:
     """Specifies the instances that write various streams.
 
     Attributes:
-        events: The instances that write to the event and backfill streams.
-        typing: The instance that writes to the typing stream.
+        events: The instance that writes to the event and backfill streams.
+        events: The instance that writes to the typing stream.
     """
 
-    events = attr.ib(
-        default=["master"], type=List[str], converter=_instance_to_list_converter
-    )
+    events = attr.ib(default="master", type=str)
     typing = attr.ib(default="master", type=str)
 
 
@@ -119,18 +105,15 @@ class WorkerConfig(Config):
         writers = config.get("stream_writers") or {}
         self.writers = WriterLocations(**writers)
 
-        # Check that the configured writers for events and typing also appears in
+        # Check that the configured writer for events and typing also appears in
         # `instance_map`.
         for stream in ("events", "typing"):
-            instances = _instance_to_list_converter(getattr(self.writers, stream))
-            for instance in instances:
-                if instance != "master" and instance not in self.instance_map:
-                    raise ConfigError(
-                        "Instance %r is configured to write %s but does not appear in `instance_map` config."
-                        % (instance, stream)
-                    )
-
-        self.events_shard_config = ShardedWorkerHandlingConfig(self.writers.events)
+            instance = getattr(self.writers, stream)
+            if instance != "master" and instance not in self.instance_map:
+                raise ConfigError(
+                    "Instance %r is configured to write %s but does not appear in `instance_map` config."
+                    % (instance, stream)
+                )
 
     def generate_config_section(self, config_dir_path, server_name, **kwargs):
         return """\