Add config option for setting homeserver's default room version (#5223)

Replaces DEFAULT_ROOM_VERSION constant with a method that first checks the config, then returns a hardcoded value if the option is not present.

That hardcoded value is now located in the server.py config file.

4 files changed, 42 insertions, 8 deletions

diff --git a/synapse/api/room_versions.py b/synapse/api/room_versions.py
index b2895355a8..4085bd10b9 100644
--- a/synapse/api/room_versions.py
+++ b/synapse/api/room_versions.py
@@ -85,10 +85,6 @@ class RoomVersions(object):
     )
 
 
-# the version we will give rooms which are created on this server
-DEFAULT_ROOM_VERSION = RoomVersions.V1
-
-
 KNOWN_ROOM_VERSIONS = {
     v.identifier: v for v in (
         RoomVersions.V1,
diff --git a/synapse/config/server.py b/synapse/config/server.py
index f34aa42afa..e9120d4d75 100644
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -20,6 +20,7 @@ import os.path
 
 from netaddr import IPSet
 
+from synapse.api.room_versions import KNOWN_ROOM_VERSIONS
 from synapse.http.endpoint import parse_and_validate_server_name
 from synapse.python_dependencies import DependencyException, check_requirements
 
@@ -35,6 +36,8 @@ logger = logging.Logger(__name__)
 # in the list.
 DEFAULT_BIND_ADDRESSES = ['::', '0.0.0.0']
 
+DEFAULT_ROOM_VERSION = "1"
+
 
 class ServerConfig(Config):
 
@@ -88,6 +91,22 @@ class ServerConfig(Config):
             "restrict_public_rooms_to_local_users", False,
         )
 
+        default_room_version = config.get(
+            "default_room_version", DEFAULT_ROOM_VERSION,
+        )
+
+        # Ensure room version is a str
+        default_room_version = str(default_room_version)
+
+        if default_room_version not in KNOWN_ROOM_VERSIONS:
+            raise ConfigError(
+                "Unknown default_room_version: %s, known room versions: %s" %
+                (default_room_version, list(KNOWN_ROOM_VERSIONS.keys()))
+            )
+
+        # Get the actual room version object rather than just the identifier
+        self.default_room_version = KNOWN_ROOM_VERSIONS[default_room_version]
+
         # whether to enable search. If disabled, new entries will not be inserted
         # into the search tables and they will not be indexed. Users will receive
         # errors when attempting to search for messages.
@@ -310,6 +329,10 @@ class ServerConfig(Config):
             unsecure_port = 8008
 
         pid_file = os.path.join(data_dir_path, "homeserver.pid")
+
+        # Bring DEFAULT_ROOM_VERSION into the local-scope for use in the
+        # default config string
+        default_room_version = DEFAULT_ROOM_VERSION
         return """\
         ## Server ##
 
@@ -384,6 +407,15 @@ class ServerConfig(Config):
         #
         #restrict_public_rooms_to_local_users: true
 
+        # The default room version for newly created rooms.
+        #
+        # Known room versions are listed here:
+        # https://matrix.org/docs/spec/#complete-list-of-room-versions
+        #
+        # For example, for room version 1, default_room_version should be set
+        # to "1".
+        #default_room_version: "%(default_room_version)s"
+
         # The GC threshold parameters to pass to `gc.set_threshold`, if defined
         #
         #gc_thresholds: [700, 10, 10]
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index e37ae96899..4a17911a87 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -27,7 +27,7 @@ from twisted.internet import defer
 
 from synapse.api.constants import EventTypes, JoinRules, RoomCreationPreset
 from synapse.api.errors import AuthError, Codes, NotFoundError, StoreError, SynapseError
-from synapse.api.room_versions import DEFAULT_ROOM_VERSION, KNOWN_ROOM_VERSIONS
+from synapse.api.room_versions import KNOWN_ROOM_VERSIONS
 from synapse.storage.state import StateFilter
 from synapse.types import RoomAlias, RoomID, RoomStreamToken, StreamToken, UserID
 from synapse.util import stringutils
@@ -70,6 +70,7 @@ class RoomCreationHandler(BaseHandler):
         self.spam_checker = hs.get_spam_checker()
         self.event_creation_handler = hs.get_event_creation_handler()
         self.room_member_handler = hs.get_room_member_handler()
+        self.config = hs.config
 
         # linearizer to stop two upgrades happening at once
         self._upgrade_linearizer = Linearizer("room_upgrade_linearizer")
@@ -475,7 +476,11 @@ class RoomCreationHandler(BaseHandler):
         if ratelimit:
             yield self.ratelimit(requester)
 
-        room_version = config.get("room_version", DEFAULT_ROOM_VERSION.identifier)
+        room_version = config.get(
+            "room_version",
+            self.config.default_room_version.identifier,
+        )
+
         if not isinstance(room_version, string_types):
             raise SynapseError(
                 400,
diff --git a/synapse/rest/client/v2_alpha/capabilities.py b/synapse/rest/client/v2_alpha/capabilities.py
index a868d06098..2b4892330c 100644
--- a/synapse/rest/client/v2_alpha/capabilities.py
+++ b/synapse/rest/client/v2_alpha/capabilities.py
@@ -16,7 +16,7 @@ import logging
 
 from twisted.internet import defer
 
-from synapse.api.room_versions import DEFAULT_ROOM_VERSION, KNOWN_ROOM_VERSIONS
+from synapse.api.room_versions import KNOWN_ROOM_VERSIONS
 from synapse.http.servlet import RestServlet
 
 from ._base import client_v2_patterns
@@ -36,6 +36,7 @@ class CapabilitiesRestServlet(RestServlet):
         """
         super(CapabilitiesRestServlet, self).__init__()
         self.hs = hs
+        self.config = hs.config
         self.auth = hs.get_auth()
         self.store = hs.get_datastore()
 
@@ -48,7 +49,7 @@ class CapabilitiesRestServlet(RestServlet):
         response = {
             "capabilities": {
                 "m.room_versions": {
-                    "default": DEFAULT_ROOM_VERSION.identifier,
+                    "default": self.config.default_room_version.identifier,
                     "available": {
                         v.identifier: v.disposition
                         for v in KNOWN_ROOM_VERSIONS.values()