Factor out _configure_named_resource

This was a bit of a code vomit, so let's factor it out to preserve some sanity

synapse/app/homeserver.py

@@ -107,9 +107,59 @@ class SynapseHomeServer(HomeServer):
         resources = {}
         for res in listener_config["resources"]:
             for name in res["names"]:
+                resources.update(self._configure_named_resource(
+                    name, res.get("compress", False),
+                ))
+
+        if WEB_CLIENT_PREFIX in resources:
+            root_resource = RootRedirect(WEB_CLIENT_PREFIX)
+        else:
+            root_resource = Resource()
+
+        root_resource = create_resource_tree(resources, root_resource)
+
+        if tls:
+            for address in bind_addresses:
+                reactor.listenSSL(
+                    port,
+                    SynapseSite(
+                        "synapse.access.https.%s" % (site_tag,),
+                        site_tag,
+                        listener_config,
+                        root_resource,
+                    ),
+                    self.tls_server_context_factory,
+                    interface=address
+                )
+        else:
+            for address in bind_addresses:
+                reactor.listenTCP(
+                    port,
+                    SynapseSite(
+                        "synapse.access.http.%s" % (site_tag,),
+                        site_tag,
+                        listener_config,
+                        root_resource,
+                    ),
+                    interface=address
+                )
+        logger.info("Synapse now listening on port %d", port)
+
+    def _configure_named_resource(self, name, compress=False):
+        """Build a resource map for a named resource
+
+        Args:
+            name (str): named resource: one of "client", "federation", etc
+            compress (bool): whether to enable gzip compression for this
+                resource
+
+        Returns:
+            dict[str, Resource]: map from path to HTTP resource
+        """
+        resources = {}
         if name == "client":
             client_resource = ClientRestResource(self)
-                    if res["compress"]:
+            if compress:
                 client_resource = gz_wrap(client_resource)
 
             resources.update({
@@ -154,39 +204,7 @@ class SynapseHomeServer(HomeServer):
         if name == "metrics" and self.get_config().enable_metrics:
             resources[METRICS_PREFIX] = MetricsResource(self)
 
-        if WEB_CLIENT_PREFIX in resources:
-            root_resource = RootRedirect(WEB_CLIENT_PREFIX)
-        else:
-            root_resource = Resource()
-
-        root_resource = create_resource_tree(resources, root_resource)
-
-        if tls:
-            for address in bind_addresses:
-                reactor.listenSSL(
-                    port,
-                    SynapseSite(
-                        "synapse.access.https.%s" % (site_tag,),
-                        site_tag,
-                        listener_config,
-                        root_resource,
-                    ),
-                    self.tls_server_context_factory,
-                    interface=address
-                )
-        else:
-            for address in bind_addresses:
-                reactor.listenTCP(
-                    port,
-                    SynapseSite(
-                        "synapse.access.http.%s" % (site_tag,),
-                        site_tag,
-                        listener_config,
-                        root_resource,
-                    ),
-                    interface=address
-                )
-        logger.info("Synapse now listening on port %d", port)
+        return resources
 
     def start_listening(self):
         config = self.get_config()