restore RootRedirect and use STATIC_PREFIX as URL for the homepage

somehow this introduced the bug that synapse tried to handle all URL's
to be relative to STATIC_PREFIX so all endpoints got not handled
any longer. This commit introduces a redirect to `/_matrix/static` where
the homepage gets automatically served to circumvent this bug.

synapse/app/homeserver.py

@@ -32,6 +32,7 @@
 from synapse.federation.transport.server import TransportLayerServer
 from synapse.module_api import ModuleApi
 from synapse.http.additional_resource import AdditionalResource
+from synapse.http.server import RootRedirect
 from synapse.http.site import SynapseSite
 from synapse.metrics import register_memory_metrics
 from synapse.metrics.resource import METRICS_PREFIX, MetricsResource
@@ -92,12 +93,7 @@ def _listener_http(self, config, listener_config):
             handler = handler_cls(config, module_api)
             resources[path] = AdditionalResource(self, handler.handle_request)
 
-        # redirect old webclients to root
-        resources[WEB_CLIENT_PREFIX] = Redirect("/")
-
-        root_resource = File(
-            os.path.join(os.path.dirname(synapse.__file__), "static")
-        )
+        root_resource = RootRedirect(STATIC_PREFIX)
 
         root_resource = create_resource_tree(resources, root_resource)
 
@@ -140,6 +136,11 @@ def _configure_named_resource(self, name, compress=False):
             dict[str, Resource]: map from path to HTTP resource
         """
         resources = {}
+        if name == "webclient":
+            # redirect old webclients to root
+            logger.warn("DEPRECATED: Handling of %s got removed from synapse. Please unconfigure it", WEB_CLIENT_PREFIX)
+            resources[WEB_CLIENT_PREFIX] = Redirect(STATIC_PREFIX)
+
         if name == "client":
             client_resource = ClientRestResource(self)
             if compress:

synapse/http/server.py

@@ -30,6 +30,7 @@
 from twisted.internet import defer
 from twisted.web import server, resource
 from twisted.web.server import NOT_DONE_YET
+from twisted.web.util import redirectTo
 
 import collections
 import logging
@@ -338,6 +339,22 @@ def stop(self, clock, request):
         )
 
 
+class RootRedirect(resource.Resource):
+    """Redirects the root '/' path to another path."""
+
+    def __init__(self, path):
+        resource.Resource.__init__(self)
+        self.url = path
+
+    def render_GET(self, request):
+        return redirectTo(self.url, request)
+
+    def getChild(self, name, request):
+        if len(name) == 0:
+            return self  # select ourselves as the child to render
+        return resource.Resource.getChild(self, name, request)
+
+
 def respond_with_json(request, code, json_object, send_cors=False,
                       response_code_message=None, pretty_print=False,
                       version_string="", canonical_json=True):