Fix #1655 by re-adding the appservice alias query (#1660)

roomserver/api/api.go

@@ -3,6 +3,7 @@ package api
 import (
 	"context"
 
+	asAPI "github.com/matrix-org/dendrite/appservice/api"
 	fsAPI "github.com/matrix-org/dendrite/federationsender/api"
 )
 
@@ -11,6 +12,7 @@ type RoomserverInternalAPI interface {
 	// needed to avoid chicken and egg scenario when setting up the
 	// interdependencies between the roomserver and other input APIs
 	SetFederationSenderAPI(fsAPI fsAPI.FederationSenderInternalAPI)
+	SetAppserviceAPI(asAPI asAPI.AppServiceQueryAPI)
 
 	InputRoomEvents(
 		ctx context.Context,

roomserver/api/api_trace.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 
+	asAPI "github.com/matrix-org/dendrite/appservice/api"
 	fsAPI "github.com/matrix-org/dendrite/federationsender/api"
 	"github.com/matrix-org/util"
 )
@@ -19,6 +20,10 @@ func (t *RoomserverInternalAPITrace) SetFederationSenderAPI(fsAPI fsAPI.Federati
 	t.Impl.SetFederationSenderAPI(fsAPI)
 }
 
+func (t *RoomserverInternalAPITrace) SetAppserviceAPI(asAPI asAPI.AppServiceQueryAPI) {
+	t.Impl.SetAppserviceAPI(asAPI)
+}
+
 func (t *RoomserverInternalAPITrace) InputRoomEvents(
 	ctx context.Context,
 	req *InputRoomEventsRequest,

roomserver/internal/alias.go

@@ -23,6 +23,8 @@ import (
 
 	"github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/gomatrixserverlib"
+
+	asAPI "github.com/matrix-org/dendrite/appservice/api"
 )
 
 // RoomserverInternalAPIDatabase has the storage APIs needed to implement the alias API.
@@ -90,17 +92,13 @@ func (r *RoomserverInternalAPI) GetRoomIDForAlias(
 		return err
 	}
 
-	/*
-		TODO: Why is this here? It creates an unnecessary dependency
-		from the roomserver to the appservice component, which should be
-		altogether optional.
-
+	if r.asAPI != nil { // appservice component is wired in
 		if roomID == "" {
 			// No room found locally, try our application services by making a call to
 			// the appservice component
-			aliasReq := appserviceAPI.RoomAliasExistsRequest{Alias: request.Alias}
-			var aliasResp appserviceAPI.RoomAliasExistsResponse
-			if err = r.AppserviceAPI.RoomAliasExists(ctx, &aliasReq, &aliasResp); err != nil {
+			aliasReq := asAPI.RoomAliasExistsRequest{Alias: request.Alias}
+			var aliasResp asAPI.RoomAliasExistsResponse
+			if err = r.asAPI.RoomAliasExists(ctx, &aliasReq, &aliasResp); err != nil {
 				return err
 			}
 
@@ -111,7 +109,7 @@ func (r *RoomserverInternalAPI) GetRoomIDForAlias(
 				}
 			}
 		}
-	*/
+	}
 
 	response.RoomID = roomID
 	return nil

roomserver/internal/api.go

@@ -4,6 +4,7 @@ import (
 	"context"
 
 	"github.com/Shopify/sarama"
+	asAPI "github.com/matrix-org/dendrite/appservice/api"
 	fsAPI "github.com/matrix-org/dendrite/federationsender/api"
 	"github.com/matrix-org/dendrite/internal/caching"
 	"github.com/matrix-org/dendrite/roomserver/acls"
@@ -35,6 +36,7 @@ type RoomserverInternalAPI struct {
 	ServerName             gomatrixserverlib.ServerName
 	KeyRing                gomatrixserverlib.JSONVerifier
 	fsAPI                  fsAPI.FederationSenderInternalAPI
+	asAPI                  asAPI.AppServiceQueryAPI
 	OutputRoomEventTopic   string // Kafka topic for new output room events
 	PerspectiveServerNames []gomatrixserverlib.ServerName
 }
@@ -126,6 +128,10 @@ func (r *RoomserverInternalAPI) SetFederationSenderAPI(fsAPI fsAPI.FederationSen
 	}
 }
 
+func (r *RoomserverInternalAPI) SetAppserviceAPI(asAPI asAPI.AppServiceQueryAPI) {
+	r.asAPI = asAPI
+}
+
 func (r *RoomserverInternalAPI) PerformInvite(
 	ctx context.Context,
 	req *api.PerformInviteRequest,

roomserver/inthttp/client.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"net/http"
 
+	asAPI "github.com/matrix-org/dendrite/appservice/api"
 	fsInputAPI "github.com/matrix-org/dendrite/federationsender/api"
 	"github.com/matrix-org/dendrite/internal/caching"
 	"github.com/matrix-org/dendrite/internal/httputil"
@@ -84,6 +85,10 @@ func NewRoomserverClient(
 func (h *httpRoomserverInternalAPI) SetFederationSenderAPI(fsAPI fsInputAPI.FederationSenderInternalAPI) {
 }
 
+// SetAppserviceAPI no-ops in HTTP client mode as there is no chicken/egg scenario
+func (h *httpRoomserverInternalAPI) SetAppserviceAPI(asAPI asAPI.AppServiceQueryAPI) {
+}
+
 // SetRoomAlias implements RoomserverAliasAPI
 func (h *httpRoomserverInternalAPI) SetRoomAlias(
 	ctx context.Context,