Deprecate the groups/communities endpoints and add an experimental configuration flag. (#12200)

changelog.d/12200.removal

@@ -0,0 +1 @@
+The groups/communities feature in Synapse has been deprecated.

docs/upgrade.md

@@ -85,6 +85,20 @@ process, for example:
     dpkg -i matrix-synapse-py3_1.3.0+stretch1_amd64.deb
     ```
 
+# Upgrading to v1.56.0
+
+## Groups/communities feature has been deprecated
+
+The non-standard groups/communities feature in Synapse has been deprecated and will
+be disabled by default in Synapse v1.58.0.
+
+You can test disabling it by adding the following to your homeserver configuration:
+
+```yaml
+experimental_features:
+  groups_enabled: false
+```
+
 # Upgrading to v1.55.0
 
 ## `synctl` script has been moved

synapse/app/generic_worker.py

@@ -322,6 +322,7 @@ class GenericWorkerServer(HomeServer):
 
                     presence.register_servlets(self, resource)
 
+                    if self.config.experimental.groups_enabled:
                         groups.register_servlets(self, resource)
 
                     resources.update({CLIENT_API_PREFIX: resource})

synapse/config/experimental.py

@@ -74,3 +74,6 @@ class ExperimentalConfig(Config):
 
         # MSC3720 (Account status endpoint)
         self.msc3720_enabled: bool = experimental.get("msc3720_enabled", False)
+
+        # The deprecated groups feature.
+        self.groups_enabled: bool = experimental.get("groups_enabled", True)

synapse/federation/transport/server/__init__.py

@@ -289,7 +289,7 @@ class OpenIdUserInfo(BaseFederationServlet):
         return 200, {"sub": user_id}
 
 
-DEFAULT_SERVLET_GROUPS: Dict[str, Iterable[Type[BaseFederationServlet]]] = {
+SERVLET_GROUPS: Dict[str, Iterable[Type[BaseFederationServlet]]] = {
     "federation": FEDERATION_SERVLET_CLASSES,
     "room_list": (PublicRoomList,),
     "group_server": GROUP_SERVER_SERVLET_CLASSES,
@@ -298,6 +298,10 @@ DEFAULT_SERVLET_GROUPS: Dict[str, Iterable[Type[BaseFederationServlet]]] = {
     "openid": (OpenIdUserInfo,),
 }
 
+DEFAULT_SERVLET_GROUPS = ("federation", "room_list", "openid")
+
+GROUP_SERVLET_GROUPS = ("group_server", "group_local", "group_attestation")
+
 
 def register_servlets(
     hs: "HomeServer",
@@ -320,16 +324,19 @@ def register_servlets(
             Defaults to ``DEFAULT_SERVLET_GROUPS``.
     """
     if not servlet_groups:
-        servlet_groups = DEFAULT_SERVLET_GROUPS.keys()
+        servlet_groups = DEFAULT_SERVLET_GROUPS
+        # Only allow the groups servlets if the deprecated groups feature is enabled.
+        if hs.config.experimental.groups_enabled:
+            servlet_groups = servlet_groups + GROUP_SERVLET_GROUPS
 
     for servlet_group in servlet_groups:
         # Skip unknown servlet groups.
-        if servlet_group not in DEFAULT_SERVLET_GROUPS:
+        if servlet_group not in SERVLET_GROUPS:
             raise RuntimeError(
                 f"Attempting to register unknown federation servlet: '{servlet_group}'"
             )
 
-        for servletclass in DEFAULT_SERVLET_GROUPS[servlet_group]:
+        for servletclass in SERVLET_GROUPS[servlet_group]:
             # Only allow the `/timestamp_to_event` servlet if msc3030 is enabled
             if (
                 servletclass == FederationTimestampLookupServlet

synapse/rest/__init__.py

@@ -118,6 +118,7 @@ class ClientRestResource(JsonResource):
         thirdparty.register_servlets(hs, client_resource)
         sendtodevice.register_servlets(hs, client_resource)
         user_directory.register_servlets(hs, client_resource)
+        if hs.config.experimental.groups_enabled:
             groups.register_servlets(hs, client_resource)
         room_upgrade_rest_servlet.register_servlets(hs, client_resource)
         room_batch.register_servlets(hs, client_resource)

synapse/rest/admin/__init__.py

@@ -293,6 +293,7 @@ def register_servlets_for_client_rest_resource(
     ResetPasswordRestServlet(hs).register(http_server)
     SearchUsersRestServlet(hs).register(http_server)
     UserRegisterServlet(hs).register(http_server)
+    if hs.config.experimental.groups_enabled:
         DeleteGroupAdminRestServlet(hs).register(http_server)
     AccountValidityRenewServlet(hs).register(http_server)