Add config key for default room version (#3171)

This PR adds a config key `room_server.default_config_key` to set the
default room version for the room server.

Signed-off-by: `Sam Wedgwood <sam@wedgwood.dev>`

12 files changed, 56 insertions, 36 deletions

diff --git a/clientapi/clientapi_test.go b/clientapi/clientapi_test.go
index ae14d271..82ec9fea 100644
--- a/clientapi/clientapi_test.go
+++ b/clientapi/clientapi_test.go
@@ -923,13 +923,17 @@ func TestCapabilities(t *testing.T) {
 		}
 	}
 
+	var tempRoomServerCfg config.RoomServer
+	tempRoomServerCfg.Defaults(config.DefaultOpts{})
+	defaultRoomVersion := tempRoomServerCfg.DefaultRoomVersion
+
 	expectedMap := map[string]interface{}{
 		"capabilities": map[string]interface{}{
 			"m.change_password": map[string]bool{
 				"enabled": true,
 			},
 			"m.room_versions": map[string]interface{}{
-				"default":   version.DefaultRoomVersion(),
+				"default":   defaultRoomVersion,
 				"available": versionsMap,
 			},
 		},
diff --git a/clientapi/routing/capabilities.go b/clientapi/routing/capabilities.go
index fa50fa1a..38e5bd46 100644
--- a/clientapi/routing/capabilities.go
+++ b/clientapi/routing/capabilities.go
@@ -17,6 +17,7 @@ package routing
 import (
 	"net/http"
 
+	roomserverAPI "github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/dendrite/roomserver/version"
 	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/matrix-org/util"
@@ -24,7 +25,7 @@ import (
 
 // GetCapabilities returns information about the server's supported feature set
 // and other relevant capabilities to an authenticated user.
-func GetCapabilities() util.JSONResponse {
+func GetCapabilities(rsAPI roomserverAPI.ClientRoomserverAPI) util.JSONResponse {
 	versionsMap := map[gomatrixserverlib.RoomVersion]string{}
 	for v, desc := range version.SupportedRoomVersions() {
 		if desc.Stable() {
@@ -40,7 +41,7 @@ func GetCapabilities() util.JSONResponse {
 				"enabled": true,
 			},
 			"m.room_versions": map[string]interface{}{
-				"default":   version.DefaultRoomVersion(),
+				"default":   rsAPI.DefaultRoomVersion(),
 				"available": versionsMap,
 			},
 		},
diff --git a/clientapi/routing/createroom.go b/clientapi/routing/createroom.go
index 320f236c..47e3ba1c 100644
--- a/clientapi/routing/createroom.go
+++ b/clientapi/routing/createroom.go
@@ -171,7 +171,7 @@ func createRoom(
 
 	// Clobber keys: creator, room_version
 
-	roomVersion := roomserverVersion.DefaultRoomVersion()
+	roomVersion := rsAPI.DefaultRoomVersion()
 	if createRequest.RoomVersion != "" {
 		candidateVersion := gomatrixserverlib.RoomVersion(createRequest.RoomVersion)
 		_, roomVersionError := roomserverVersion.SupportedRoomVersion(candidateVersion)
diff --git a/clientapi/routing/routing.go b/clientapi/routing/routing.go
index 8cd207b7..8b3ae5e1 100644
--- a/clientapi/routing/routing.go
+++ b/clientapi/routing/routing.go
@@ -1256,7 +1256,7 @@ func Setup(
 			if r := rateLimits.Limit(req, device); r != nil {
 				return *r
 			}
-			return GetCapabilities()
+			return GetCapabilities(rsAPI)
 		}, httputil.WithAllowGuests()),
 	).Methods(http.MethodGet, http.MethodOptions)
 
diff --git a/clientapi/routing/server_notices.go b/clientapi/routing/server_notices.go
index 66258a68..1c5d693c 100644
--- a/clientapi/routing/server_notices.go
+++ b/clientapi/routing/server_notices.go
@@ -28,7 +28,6 @@ import (
 	"github.com/sirupsen/logrus"
 
 	"github.com/matrix-org/dendrite/roomserver/types"
-	"github.com/matrix-org/dendrite/roomserver/version"
 
 	appserviceAPI "github.com/matrix-org/dendrite/appservice/api"
 	"github.com/matrix-org/dendrite/clientapi/httputil"
@@ -135,7 +134,7 @@ func SendServerNotice(
 
 	var (
 		roomID      string
-		roomVersion = version.DefaultRoomVersion()
+		roomVersion = rsAPI.DefaultRoomVersion()
 	)
 
 	// create a new room for the user
diff --git a/go.mod b/go.mod
index 74b17166..ae37b2e7 100644
--- a/go.mod
+++ b/go.mod
@@ -22,7 +22,7 @@ require (
 	github.com/matrix-org/dugong v0.0.0-20210921133753-66e6b1c67e2e
 	github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91
 	github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530
-	github.com/matrix-org/gomatrixserverlib v0.0.0-20230802090652-1b697d109d87
+	github.com/matrix-org/gomatrixserverlib v0.0.0-20230807152937-c48e302e15ac
 	github.com/matrix-org/pinecone v0.11.1-0.20230210171230-8c3b24f2649a
 	github.com/matrix-org/util v0.0.0-20221111132719-399730281e66
 	github.com/mattn/go-sqlite3 v1.14.17
@@ -42,12 +42,12 @@ require (
 	github.com/uber/jaeger-lib v2.4.1+incompatible
 	github.com/yggdrasil-network/yggdrasil-go v0.4.6
 	go.uber.org/atomic v1.10.0
-	golang.org/x/crypto v0.11.0
+	golang.org/x/crypto v0.12.0
 	golang.org/x/exp v0.0.0-20221205204356-47842c84f3db
 	golang.org/x/image v0.5.0
 	golang.org/x/mobile v0.0.0-20221020085226-b36e6246172e
 	golang.org/x/sync v0.2.0
-	golang.org/x/term v0.10.0
+	golang.org/x/term v0.11.0
 	gopkg.in/h2non/bimg.v1 v1.1.9
 	gopkg.in/yaml.v2 v2.4.0
 	gotest.tools/v3 v3.4.0
@@ -127,8 +127,8 @@ require (
 	go.etcd.io/bbolt v1.3.6 // indirect
 	golang.org/x/mod v0.8.0 // indirect
 	golang.org/x/net v0.10.0 // indirect
-	golang.org/x/sys v0.10.0 // indirect
-	golang.org/x/text v0.11.0 // indirect
+	golang.org/x/sys v0.11.0 // indirect
+	golang.org/x/text v0.12.0 // indirect
 	golang.org/x/time v0.3.0 // indirect
 	golang.org/x/tools v0.6.0 // indirect
 	google.golang.org/protobuf v1.30.0 // indirect
diff --git a/go.sum b/go.sum
index 779c2861..e744d2d3 100644
--- a/go.sum
+++ b/go.sum
@@ -113,7 +113,6 @@ github.com/glycerine/go-unsnap-stream v0.0.0-20180323001048-9f0cb55181dd/go.mod
 github.com/glycerine/goconvey v0.0.0-20180728074245-46e3a41ad493/go.mod h1:Ogl1Tioa0aV7gstGFO7KhffUsb9M4ydbEbbxpcEDc24=
 github.com/go-errors/errors v1.4.2 h1:J6MZopCL4uSllY1OfXM374weqZFFItUbrImctkmUxIA=
 github.com/go-gl/glfw v0.0.0-20190409004039-e6da0acd62b1/go.mod h1:vR7hzQXu2zJy9AVAgeJqvqgH9Q5CA+iKCZ2gyEVpxRU=
-github.com/go-logfmt/logfmt v0.5.1/go.mod h1:WYhtIu8zTZfxdn5+rREduYbwxfcBr/Vr6KEVveWlfTs=
 github.com/go-playground/assert/v2 v2.0.1/go.mod h1:VDjEfimB/XKnb+ZQfWdccd7VUvScMdVu0Titje2rxJ4=
 github.com/go-playground/locales v0.13.0/go.mod h1:taPMhCMXrRLJO55olJkUXHZBHCxTMfnGwq/HNwmWNS8=
 github.com/go-playground/locales v0.14.0 h1:u50s323jtVGugKlcYeyzC0etD1HifMjqmJqb8WugfUU=
@@ -176,14 +175,12 @@ github.com/h2non/filetype v1.1.3/go.mod h1:319b3zT68BvV+WRj7cwy856M2ehB3HqNOt6sy
 github.com/h2non/parth v0.0.0-20190131123155-b4df798d6542 h1:2VTzZjLZBgl62/EtslCrtky5vbi9dd7HrQPQIx6wqiw=
 github.com/huandu/xstrings v1.0.0 h1:pO2K/gKgKaat5LdpAhxhluX2GPQMaI3W5FUz/I/UnWk=
 github.com/huandu/xstrings v1.0.0/go.mod h1:4qWG/gcEcfX4z/mBDHJ++3ReCw9ibxbsNJbcucJdbSo=
-github.com/jpillora/backoff v1.0.0/go.mod h1:J/6gKK9jxlEcS3zixgDgUAsiuZ7yrSoa/FX5e0EB2j4=
 github.com/json-iterator/go v1.1.9/go.mod h1:KdQUCv79m/52Kvf8AW2vK1V8akMuk1QjK/uOdHXbAo4=
 github.com/json-iterator/go v1.1.12 h1:PV8peI4a0ysnczrg+LtxykD8LfKY9ML6u2jnxaEnrnM=
 github.com/json-iterator/go v1.1.12/go.mod h1:e30LSqwooZae/UwlEbR2852Gd8hjQvJoHmT4TnhNGBo=
 github.com/jtolds/gls v4.2.1+incompatible/go.mod h1:QJZ7F/aHp+rZTRtaJ1ow/lLfFfVYBRgL+9YlvaHOwJU=
 github.com/juju/errors v1.0.0 h1:yiq7kjCLll1BiaRuNY53MGI0+EQ3rF6GB+wvboZDefM=
 github.com/juju/errors v1.0.0/go.mod h1:B5x9thDqx0wIMH3+aLIMP9HjItInYWObRovoCFM5Qe8=
-github.com/julienschmidt/httprouter v1.3.0/go.mod h1:JR6WtHb+2LUe8TCKY3cZOxFyyO8IZAc4RVcycCCAKdM=
 github.com/jung-kurt/gofpdf v1.0.3-0.20190309125859-24315acbbda5/go.mod h1:7Id9E/uU8ce6rXgefFLlgrJj/GYY22cpxn+r32jIOes=
 github.com/kardianos/minwinsvc v1.0.2 h1:JmZKFJQrmTGa/WiW+vkJXKmfzdjabuEW4Tirj5lLdR0=
 github.com/kardianos/minwinsvc v1.0.2/go.mod h1:LUZNYhNmxujx2tR7FbdxqYJ9XDDoCd3MQcl1o//FWl4=
@@ -210,10 +207,8 @@ github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91 h1:s7fexw
 github.com/matrix-org/go-sqlite3-js v0.0.0-20220419092513-28aa791a1c91/go.mod h1:e+cg2q7C7yE5QnAXgzo512tgFh1RbQLC0+jozuegKgo=
 github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530 h1:kHKxCOLcHH8r4Fzarl4+Y3K5hjothkVW5z7T1dUM11U=
 github.com/matrix-org/gomatrix v0.0.0-20220926102614-ceba4d9f7530/go.mod h1:/gBX06Kw0exX1HrwmoBibFA98yBk/jxKpGVeyQbff+s=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20230801102756-b66c2627dc08 h1:uy1mlUraKrEbUzZ3KrSQp/nLxMccVhIJM8mZSIbQzeA=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20230801102756-b66c2627dc08/go.mod h1:H9V9N3Uqn1bBJqYJNGK1noqtgJTaCEhtTdcH/mp50uU=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20230802090652-1b697d109d87 h1:z0RFUknidOShRxkvjT3ovGCWnusyplu6OLjFHcbDYaE=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20230802090652-1b697d109d87/go.mod h1:H9V9N3Uqn1bBJqYJNGK1noqtgJTaCEhtTdcH/mp50uU=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20230807152937-c48e302e15ac h1:s4EZRNT6/TtGAzcO6yzL+UTv96vEeeaH6y2RrIOfsWw=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20230807152937-c48e302e15ac/go.mod h1:H9V9N3Uqn1bBJqYJNGK1noqtgJTaCEhtTdcH/mp50uU=
 github.com/matrix-org/pinecone v0.11.1-0.20230210171230-8c3b24f2649a h1:awrPDf9LEFySxTLKYBMCiObelNx/cBuv/wzllvCCH3A=
 github.com/matrix-org/pinecone v0.11.1-0.20230210171230-8c3b24f2649a/go.mod h1:HchJX9oKMXaT2xYFs0Ha/6Zs06mxLU8k6F1ODnrGkeQ=
 github.com/matrix-org/util v0.0.0-20221111132719-399730281e66 h1:6z4KxomXSIGWqhHcfzExgkH3Z3UkIXry4ibJS4Aqz2Y=
@@ -246,7 +241,6 @@ github.com/morikuni/aec v1.0.0/go.mod h1:BbKIizmSmc5MMPqRYbxO4ZU0S0+P200+tUnFx7P
 github.com/mschoch/smat v0.0.0-20160514031455-90eadee771ae/go.mod h1:qAyveg+e4CE+eKJXWVjKXM4ck2QobLqTDytGJbLLhJg=
 github.com/mschoch/smat v0.2.0 h1:8imxQsjDm8yFEAVBe7azKmKSgzSkZXDuKkSq9374khM=
 github.com/mschoch/smat v0.2.0/go.mod h1:kc9mz7DoBKqDyiRL7VZN8KvXQMWeTaVnttLRXOlotKw=
-github.com/mwitkow/go-conntrack v0.0.0-20190716064945-2f068394615f/go.mod h1:qRWi+5nqEBWmkhHvq77mSJWrCKwh8bxhgT7d/eI7P4U=
 github.com/nats-io/jwt/v2 v2.4.1 h1:Y35W1dgbbz2SQUYDPCaclXcuqleVmpbRa7646Jf2EX4=
 github.com/nats-io/jwt/v2 v2.4.1/go.mod h1:24BeQtRwxRV8ruvC4CojXlx/WQ/VjuwlYiH+vu/+ibI=
 github.com/nats-io/nats-server/v2 v2.9.19 h1:OF9jSKZGo425C/FcVVIvNgpd36CUe7aVTTXEZRJk6kA=
@@ -364,8 +358,8 @@ golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8U
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/crypto v0.0.0-20210421170649-83a5a9bb288b/go.mod h1:T9bdIzuCu7OtxOm1hfPfRQxPLYneinmdGuTeoZ9dtd4=
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
-golang.org/x/crypto v0.11.0 h1:6Ewdq3tDic1mg5xRO4milcWCfMVQhI4NkqWWvqejpuA=
-golang.org/x/crypto v0.11.0/go.mod h1:xgJhtzW8F9jGdVFWZESrid1U1bjeNy4zgy5cRr/CIio=
+golang.org/x/crypto v0.12.0 h1:tFM/ta59kqch6LlvYnPa0yx5a83cL2nHflFhYKvv9Yk=
+golang.org/x/crypto v0.12.0/go.mod h1:NF0Gs7EO5K4qLn+Ylc+fih8BSTeIjAP05siRnAh98yw=
 golang.org/x/exp v0.0.0-20180321215751-8460e604b9de/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20180807140117-3d87b88a115f/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20190125153040-c74c464bbbf2/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
@@ -428,19 +422,19 @@ golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20221010170243-090e33056c14/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.10.0 h1:SqMFp9UcQJZa+pmYuAKjd9xq1f0j5rLcDIk0mj4qAsA=
-golang.org/x/sys v0.10.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.11.0 h1:eG7RXZHdqOJ1i+0lgLgCpSXAp6M3LYlAo6osgSi0xOM=
+golang.org/x/sys v0.11.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
-golang.org/x/term v0.10.0 h1:3R7pNqamzBraeqj/Tj8qt1aQ2HpmlC+Cx/qL/7hn4/c=
-golang.org/x/term v0.10.0/go.mod h1:lpqdcUyK/oCiQxvxVrppt5ggO2KCZ5QblwqPnfZ6d5o=
+golang.org/x/term v0.11.0 h1:F9tnn/DA/Im8nCwm+fX+1/eBwi4qFjRT++MhtVC4ZX0=
+golang.org/x/term v0.11.0/go.mod h1:zC9APTIj3jG3FdV/Ons+XE1riIZXG4aZ4GTHiPZJPIU=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
 golang.org/x/text v0.7.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
-golang.org/x/text v0.11.0 h1:LAntKIrcmeSKERyiOh0XMV39LXS8IE9UL2yP7+f5ij4=
-golang.org/x/text v0.11.0/go.mod h1:TvPlkZtksWOMsz7fbANvkp4WM8x/WCo/om8BMLbz+aE=
+golang.org/x/text v0.12.0 h1:k+n5B8goJNdU7hSvEtMUz3d1Q6D/XW4COJSJR6fN0mc=
+golang.org/x/text v0.12.0/go.mod h1:TvPlkZtksWOMsz7fbANvkp4WM8x/WCo/om8BMLbz+aE=
 golang.org/x/time v0.0.0-20191024005414-555d28b269f0/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/time v0.3.0 h1:rg5rLMjNzMS1RkNLzCG38eapWhnYLFYXDXj2gOlr8j4=
 golang.org/x/time v0.3.0/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
diff --git a/roomserver/api/api.go b/roomserver/api/api.go
index 69997fc4..ad6a7122 100644
--- a/roomserver/api/api.go
+++ b/roomserver/api/api.go
@@ -55,6 +55,11 @@ type RestrictedJoinAPI interface {
 	LocallyJoinedUsers(ctx context.Context, roomVersion gomatrixserverlib.RoomVersion, roomNID types.RoomNID) ([]gomatrixserverlib.PDU, error)
 }
 
+type DefaultRoomVersionAPI interface {
+	// Returns the default room version used.
+	DefaultRoomVersion() gomatrixserverlib.RoomVersion
+}
+
 // RoomserverInputAPI is used to write events to the room server.
 type RoomserverInternalAPI interface {
 	SyncRoomserverAPI
@@ -64,6 +69,7 @@ type RoomserverInternalAPI interface {
 	FederationRoomserverAPI
 	QuerySenderIDAPI
 	UserRoomPrivateKeyCreator
+	DefaultRoomVersionAPI
 
 	// needed to avoid chicken and egg scenario when setting up the
 	// interdependencies between the roomserver and other input APIs
@@ -210,6 +216,7 @@ type ClientRoomserverAPI interface {
 	QuerySenderIDAPI
 	UserRoomPrivateKeyCreator
 	QueryRoomHierarchyAPI
+	DefaultRoomVersionAPI
 	QueryMembershipForUser(ctx context.Context, req *QueryMembershipForUserRequest, res *QueryMembershipForUserResponse) error
 	QueryMembershipsForRoom(ctx context.Context, req *QueryMembershipsForRoomRequest, res *QueryMembershipsForRoomResponse) error
 	QueryRoomsForUser(ctx context.Context, req *QueryRoomsForUserRequest, res *QueryRoomsForUserResponse) error
diff --git a/roomserver/internal/api.go b/roomserver/internal/api.go
index e8899a21..530147da 100644
--- a/roomserver/internal/api.go
+++ b/roomserver/internal/api.go
@@ -61,6 +61,7 @@ type RoomserverInternalAPI struct {
 	OutputProducer         *producers.RoomEventProducer
 	PerspectiveServerNames []spec.ServerName
 	enableMetrics          bool
+	defaultRoomVersion     gomatrixserverlib.RoomVersion
 }
 
 func NewRoomserverAPI(
@@ -92,6 +93,7 @@ func NewRoomserverAPI(
 		Durable:                dendriteCfg.Global.JetStream.Durable("RoomserverInputConsumer"),
 		ServerACLs:             serverACLs,
 		enableMetrics:          enableMetrics,
+		defaultRoomVersion:     dendriteCfg.RoomServer.DefaultRoomVersion,
 		// perform-er structs + queryer struct get initialised when we have a federation sender to use
 	}
 	return a
@@ -218,6 +220,10 @@ func (r *RoomserverInternalAPI) SetAppserviceAPI(asAPI asAPI.AppServiceInternalA
 	r.asAPI = asAPI
 }
 
+func (r *RoomserverInternalAPI) DefaultRoomVersion() gomatrixserverlib.RoomVersion {
+	return r.defaultRoomVersion
+}
+
 func (r *RoomserverInternalAPI) IsKnownRoom(ctx context.Context, roomID spec.RoomID) (bool, error) {
 	return r.Inviter.IsKnownRoom(ctx, roomID)
 }
diff --git a/roomserver/roomserver_test.go b/roomserver/roomserver_test.go
index 1626bf83..47626b30 100644
--- a/roomserver/roomserver_test.go
+++ b/roomserver/roomserver_test.go
@@ -11,7 +11,6 @@ import (
 	"github.com/matrix-org/dendrite/internal/eventutil"
 	"github.com/matrix-org/dendrite/internal/httputil"
 	"github.com/matrix-org/dendrite/internal/sqlutil"
-	"github.com/matrix-org/dendrite/roomserver/version"
 	"github.com/matrix-org/gomatrixserverlib/spec"
 	"github.com/stretchr/testify/assert"
 	"github.com/tidwall/gjson"
@@ -1060,7 +1059,7 @@ func TestUpgrade(t *testing.T) {
 				if err != nil {
 					t.Fatalf("upgrade userID is invalid")
 				}
-				newRoomID, err := rsAPI.PerformRoomUpgrade(processCtx.Context(), roomID, *userID, version.DefaultRoomVersion())
+				newRoomID, err := rsAPI.PerformRoomUpgrade(processCtx.Context(), roomID, *userID, rsAPI.DefaultRoomVersion())
 				if err != nil && tc.wantNewRoom {
 					t.Fatal(err)
 				}
diff --git a/roomserver/version/version.go b/roomserver/version/version.go
index 270d4289..e8bd890a 100644
--- a/roomserver/version/version.go
+++ b/roomserver/version/version.go
@@ -20,12 +20,6 @@ import (
 	"github.com/matrix-org/gomatrixserverlib"
 )
 
-// DefaultRoomVersion contains the room version that will, by
-// default, be used to create new rooms on this server.
-func DefaultRoomVersion() gomatrixserverlib.RoomVersion {
-	return gomatrixserverlib.RoomVersionV10
-}
-
 // RoomVersions returns a map of all known room versions to this
 // server.
 func RoomVersions() map[gomatrixserverlib.RoomVersion]gomatrixserverlib.IRoomVersion {
diff --git a/setup/config/config_roomserver.go b/setup/config/config_roomserver.go
index 319c2419..06e7757f 100644
--- a/setup/config/config_roomserver.go
+++ b/setup/config/config_roomserver.go
@@ -1,12 +1,22 @@
 package config
 
+import (
+	"fmt"
+
+	"github.com/matrix-org/gomatrixserverlib"
+	log "github.com/sirupsen/logrus"
+)
+
 type RoomServer struct {
 	Matrix *Global `yaml:"-"`
 
+	DefaultRoomVersion gomatrixserverlib.RoomVersion `yaml:"default_room_version,omitempty"`
+
 	Database DatabaseOptions `yaml:"database,omitempty"`
 }
 
 func (c *RoomServer) Defaults(opts DefaultOpts) {
+	c.DefaultRoomVersion = gomatrixserverlib.RoomVersionV10
 	if opts.Generate {
 		if !opts.SingleDatabase {
 			c.Database.ConnectionString = "file:roomserver.db"
@@ -18,4 +28,10 @@ func (c *RoomServer) Verify(configErrs *ConfigErrors) {
 	if c.Matrix.DatabaseOptions.ConnectionString == "" {
 		checkNotEmpty(configErrs, "room_server.database.connection_string", string(c.Database.ConnectionString))
 	}
+
+	if !gomatrixserverlib.KnownRoomVersion(c.DefaultRoomVersion) {
+		configErrs.Add(fmt.Sprintf("invalid value for config key 'room_server.default_room_version': unsupported room version: %q", c.DefaultRoomVersion))
+	} else if !gomatrixserverlib.StableRoomVersion(c.DefaultRoomVersion) {
+		log.Warnf("WARNING: Provided default room version %q is unstable", c.DefaultRoomVersion)
+	}
 }