Adds a feature flag to control availability of DMs in shared channels (#28920)

* Adds a feature flag to control availability of DMs in shared channels

* Reverse feature flag wording

server/channels/app/channel.go

@@ -424,7 +424,7 @@ func (a *App) createDirectChannel(c request.CTX, userID string, otherUserID stri
 }
 
 func (a *App) createDirectChannelWithUser(c request.CTX, user, otherUser *model.User, channelOptions ...model.ChannelOption) (*model.Channel, *model.AppError) {
-	if user.IsRemote() || otherUser.IsRemote() {
+	if !a.Config().FeatureFlags.EnableSharedChannelsDMs && (user.IsRemote() || otherUser.IsRemote()) {
 		return nil, model.NewAppError("createDirectChannelWithUser", "api.channel.create_channel.direct_channel.remote_restricted.app_error", nil, "", http.StatusForbidden)
 	}
 
@@ -528,9 +528,11 @@ func (a *App) createGroupChannel(c request.CTX, userIDs []string) (*model.Channe
 		return nil, model.NewAppError("CreateGroupChannel", "api.channel.create_group.bad_user.app_error", nil, "user_ids="+model.ArrayToJSON(userIDs), http.StatusBadRequest)
 	}
 
-	for _, user := range users {
-		if user.IsRemote() {
-			return nil, model.NewAppError("createGroupChannel", "api.channel.create_group.remote_restricted.app_error", nil, "", http.StatusForbidden)
+	if !a.Config().FeatureFlags.EnableSharedChannelsDMs {
+		for _, user := range users {
+			if user.IsRemote() {
+				return nil, model.NewAppError("createGroupChannel", "api.channel.create_group.remote_restricted.app_error", nil, "", http.StatusForbidden)
+			}
 		}
 	}
 

server/channels/app/post.go

@@ -141,7 +141,7 @@ func (a *App) deduplicateCreatePost(rctx request.CTX, post *model.Post) (foundPo
 }
 
 func (a *App) CreatePost(c request.CTX, post *model.Post, channel *model.Channel, flags model.CreatePostFlags) (savedPost *model.Post, err *model.AppError) {
-	if channel.IsShared() && (channel.Type == model.ChannelTypeDirect || channel.Type == model.ChannelTypeGroup) {
+	if !a.Config().FeatureFlags.EnableSharedChannelsDMs && channel.IsShared() && (channel.Type == model.ChannelTypeDirect || channel.Type == model.ChannelTypeGroup) {
 		return nil, model.NewAppError("CreatePost", "app.post.create_post.shared_dm_or_gm.app_error", nil, "", http.StatusBadRequest)
 	}
 

server/platform/services/sharedchannel/service_api.go

@@ -22,7 +22,7 @@ func (scs *Service) ShareChannel(sc *model.SharedChannel) (*model.SharedChannel,
 		return nil, fmt.Errorf("cannot fetch channel while sharing channel %s: %w", sc.ChannelId, err)
 	}
 
-	if channel.Type == model.ChannelTypeDirect || channel.Type == model.ChannelTypeGroup {
+	if !scs.server.Config().FeatureFlags.EnableSharedChannelsDMs && (channel.Type == model.ChannelTypeDirect || channel.Type == model.ChannelTypeGroup) {
 		return nil, errors.New("cannot share a direct or group channel")
 	}
 

server/public/model/feature_flags.go

@@ -19,6 +19,9 @@ type FeatureFlags struct {
 	// Enable the remote cluster service for shared channels.
 	EnableRemoteClusterService bool
 
+	// Enable DMs and GMs for shared channels.
+	EnableSharedChannelsDMs bool
+
 	// AppsEnabled toggles the Apps framework functionalities both in server and client side
 	AppsEnabled bool
 
@@ -58,6 +61,7 @@ func (f *FeatureFlags) SetDefaults() {
 	f.TestFeature = "off"
 	f.TestBoolFeature = false
 	f.EnableRemoteClusterService = false
+	f.EnableSharedChannelsDMs = false
 	f.AppsEnabled = false
 	f.NormalizeLdapDNs = false
 	f.DeprecateCloudFree = false