Add EnableDefaultChannelLeaveJoinMessages config setting (#7961)

app/channel.go

@@ -63,6 +63,7 @@ func (a *App) JoinDefaultChannels(teamId string, user *model.User, channelRole s
 			l4g.Warn("Failed to update ChannelMemberHistory table %v", result.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)
@@ -72,6 +73,7 @@ func (a *App) JoinDefaultChannels(teamId string, user *model.User, channelRole s
 					l4g.Error(utils.T("api.channel.post_user_add_remove_message_and_forget.error"), err)
 				}
 			}
+		}
 
 		a.InvalidateCacheForChannelMembers(result.Data.(*model.Channel).Id)
 	}
@@ -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)
 		})

app/diagnostics.go

@@ -237,6 +237,7 @@ func (a *App) trackConfig() {
 		"enable_post_search":                                      *cfg.ServiceSettings.EnablePostSearch,
 		"enable_user_statuses":                                    *cfg.ServiceSettings.EnableUserStatuses,
 		"close_unused_direct_messages":                            *cfg.ServiceSettings.CloseUnusedDirectMessages,
+		"experimental_enable_default_channel_leave_join_messages": *cfg.ServiceSettings.ExperimentalEnableDefaultChannelLeaveJoinMessages,
 	})
 
 	a.SendDiagnostic(TRACK_CONFIG_TEAM, map[string]interface{}{

config/default.json

@@ -55,7 +55,8 @@
         "ClusterLogTimeoutMilliseconds": 2000,
         "EnablePreviewFeatures": true,
         "CloseUnusedDirectMessages": false,
-        "EnableTutorial": true
+        "EnableTutorial": true,
+        "ExperimentalEnableDefaultChannelLeaveJoinMessages": true
     },
     "TeamSettings": {
         "SiteName": "Mattermost",

model/config.go

@@ -213,6 +213,7 @@ type ServiceSettings struct {
 	CloseUnusedDirectMessages                         *bool
 	EnablePreviewFeatures                             *bool
 	EnableTutorial                                    *bool
+	ExperimentalEnableDefaultChannelLeaveJoinMessages *bool
 }
 
 func (s *ServiceSettings) SetDefaults() {
@@ -413,6 +414,10 @@ func (s *ServiceSettings) SetDefaults() {
 	if s.EnablePreviewFeatures == nil {
 		s.EnablePreviewFeatures = NewBool(true)
 	}
+
+	if s.ExperimentalEnableDefaultChannelLeaveJoinMessages == nil {
+		s.ExperimentalEnableDefaultChannelLeaveJoinMessages = NewBool(true)
+	}
 }
 
 type ClusterSettings struct {

utils/config.go

@@ -475,6 +475,7 @@ func GenerateClientConfig(c *model.Config, diagnosticId string) map[string]strin
 	props["CloseUnusedDirectMessages"] = strconv.FormatBool(*c.ServiceSettings.CloseUnusedDirectMessages)
 	props["EnablePreviewFeatures"] = strconv.FormatBool(*c.ServiceSettings.EnablePreviewFeatures)
 	props["EnableTutorial"] = strconv.FormatBool(*c.ServiceSettings.EnableTutorial)
+	props["ExperimentalEnableDefaultChannelLeaveJoinMessages"] = strconv.FormatBool(*c.ServiceSettings.ExperimentalEnableDefaultChannelLeaveJoinMessages)
 
 	props["SendEmailNotifications"] = strconv.FormatBool(c.EmailSettings.SendEmailNotifications)
 	props["SendPushNotifications"] = strconv.FormatBool(*c.EmailSettings.SendPushNotifications)