Add metric warning support (announcement bar and DM) (#14483)

* Admin. Advisory: Add warning for number of active users metric status

Co-authored-by: Catalin Tomai <catalin.tomai@mattermost.com>

app/server.go

@@ -1090,6 +1090,13 @@ func runLicenseExpirationCheckJob(a *App) {
 	}, time.Hour*24)
 }
 
+func runCheckNumberOfActiveUsersWarnMetricStatusJob(a *App) {
+	doCheckNumberOfActiveUsersWarnMetricStatus(a)
+	model.CreateRecurringTask("Check Number Of Active Users Warn Metric Status", func() {
+		doCheckNumberOfActiveUsersWarnMetricStatus(a)
+	}, time.Hour*24)
+}
+
 func doSecurity(s *Server) {
 	s.DoSecurityUpdateCheck()
 }
@@ -1117,6 +1124,58 @@ func doSessionCleanup(s *Server) {
 	s.Store.Session().Cleanup(model.GetMillis(), SESSIONS_CLEANUP_BATCH_SIZE)
 }
 
+func doCheckNumberOfActiveUsersWarnMetricStatus(a *App) {
+	license := a.Srv().License()
+	if license != nil {
+		mlog.Debug("License is present, skip this check")
+		return
+	}
+
+	numberOfActiveUsers, err := a.Srv().Store.User().Count(model.UserCountOptions{})
+	if err != nil {
+		mlog.Error("Error to get active registered users.", mlog.Err(err))
+	}
+
+	warnMetrics := []model.WarnMetric{}
+	if numberOfActiveUsers < model.WarnMetricsTable[model.SYSTEM_WARN_METRIC_NUMBER_OF_ACTIVE_USERS_200].Limit {
+		return
+	} else if numberOfActiveUsers >= model.WarnMetricsTable[model.SYSTEM_WARN_METRIC_NUMBER_OF_ACTIVE_USERS_200].Limit && numberOfActiveUsers < model.WarnMetricsTable[model.SYSTEM_WARN_METRIC_NUMBER_OF_ACTIVE_USERS_400].Limit {
+		warnMetrics = append(warnMetrics, model.WarnMetricsTable[model.SYSTEM_WARN_METRIC_NUMBER_OF_ACTIVE_USERS_200])
+	} else if numberOfActiveUsers >= model.WarnMetricsTable[model.SYSTEM_WARN_METRIC_NUMBER_OF_ACTIVE_USERS_400].Limit && numberOfActiveUsers < model.WarnMetricsTable[model.SYSTEM_WARN_METRIC_NUMBER_OF_ACTIVE_USERS_500].Limit {
+		warnMetrics = append(warnMetrics, model.WarnMetricsTable[model.SYSTEM_WARN_METRIC_NUMBER_OF_ACTIVE_USERS_400])
+	} else {
+		warnMetrics = append(warnMetrics, model.WarnMetricsTable[model.SYSTEM_WARN_METRIC_NUMBER_OF_ACTIVE_USERS_500])
+	}
+
+	for _, warnMetric := range warnMetrics {
+		data, err := a.Srv().Store.System().GetByName(warnMetric.Id)
+		if err == nil && data != nil && (data.Value == model.WARN_METRIC_STATUS_ACK || data.Value == model.WARN_METRIC_STATUS_RUNONCE) {
+			mlog.Debug("This metric warning has already been acked or should only run once")
+			continue
+		}
+
+		if err = a.Srv().Store.System().SaveOrUpdate(&model.System{Name: warnMetric.Id, Value: model.WARN_METRIC_STATUS_LIMIT_REACHED}); err != nil {
+			mlog.Error("Unable to write to database.", mlog.String("id", warnMetric.Id), mlog.Err(err))
+			continue
+		}
+		warnMetricStatus, _ := a.getWarnMetricStatusAndDisplayTextsForId(warnMetric.Id, nil)
+
+		if !warnMetric.IsBotOnly {
+			message := model.NewWebSocketEvent(model.WEBSOCKET_WARN_METRIC_STATUS_RECEIVED, "", "", "", nil)
+			message.Add("warnMetricStatus", warnMetricStatus.ToJson())
+			a.Publish(message)
+		}
+
+		if err = a.notifyAdminsOfWarnMetricStatus(warnMetric.Id); err != nil {
+			mlog.Error("Failed to send notifications to admin users.", mlog.Err(err))
+		}
+
+		if warnMetric.IsRunOnce {
+			a.setWarnMetricsStatusForId(warnMetric.Id, model.WARN_METRIC_STATUS_RUNONCE)
+		}
+	}
+}
+
 func doLicenseExpirationCheck(a *App) {
 	a.Srv().LoadLicense()
 	license := a.Srv().License()