Add EnableDefaultChannelLeaveJoinMessages config setting (#7961)

app/channel.go

@@ -63,13 +63,15 @@ func (a *App) JoinDefaultChannels(teamId string, user *model.User, channelRole s
 			l4g.Warn("Failed to update ChannelMemberHistory table %v", result.Err)
 		}
 
-		if requestor == nil {
-			if err := a.postJoinTeamMessage(user, townSquare); err != nil {
-				l4g.Error(utils.T("api.channel.post_user_add_remove_message_and_forget.error"), err)
-			}
-		} else {
-			if err := a.PostAddToTeamMessage(requestor, user, townSquare, ""); err != nil {
-				l4g.Error(utils.T("api.channel.post_user_add_remove_message_and_forget.error"), err)
+		if *a.Config().ServiceSettings.ExperimentalEnableDefaultChannelLeaveJoinMessages == true {
+			if requestor == nil {
+				if err := a.postJoinTeamMessage(user, townSquare); err != nil {
+					l4g.Error(utils.T("api.channel.post_user_add_remove_message_and_forget.error"), err)
+				}
+			} else {
+				if err := a.PostAddToTeamMessage(requestor, user, townSquare, ""); err != nil {
+					l4g.Error(utils.T("api.channel.post_user_add_remove_message_and_forget.error"), err)
+				}
 			}
 		}
 
@@ -1012,6 +1014,10 @@ func (a *App) LeaveChannel(channelId string, userId string) *model.AppError {
 			return err
 		}
 
+		if channel.Name == model.DEFAULT_CHANNEL && *a.Config().ServiceSettings.ExperimentalEnableDefaultChannelLeaveJoinMessages == false {
+			return nil
+		}
+
 		a.Go(func() {
 			a.postLeaveChannelMessage(user, channel)
 		})