Add cron schedules and sync docs

agent/internal/app/app.go

@@ -47,9 +47,7 @@ func (a *App) Run(ctx context.Context) error {
 	a.Metrics.ConfigLoadSuccess.Set(1)
 	a.Metrics.ChecksConfigured.Set(float64(len(cfg.Checks)))
 	a.Metrics.BuildInfo.WithLabelValues(a.Version, boolLabel(cfg.PushesToServer()), boolLabel(cfg.ExposesMetrics())).Set(1)
-	for _, c := range cfg.Checks {
-		a.Metrics.CheckInterval.WithLabelValues(c.ID).Set(c.Interval.Duration.Seconds())
-	}
+	a.recordCheckScheduleMetrics(cfg.Checks)
 
 	var wg sync.WaitGroup
 
@@ -256,9 +254,7 @@ func (a *App) Reload(newCfg *config.Config, newAgentID string) error {
 	a.Metrics.ConfigReloadTotal.WithLabelValues("success").Inc()
 	a.Metrics.ConfigLastReloadSuccess.Set(float64(time.Now().Unix()))
 	a.Metrics.ChecksConfigured.Set(float64(len(newCfg.Checks)))
-	for _, c := range newCfg.Checks {
-		a.Metrics.CheckInterval.WithLabelValues(c.ID).Set(c.Interval.Duration.Seconds())
-	}
+	a.recordCheckScheduleMetrics(newCfg.Checks)
 
 	a.schedulerMu.RLock()
 	mgr := a.scheduler
@@ -275,6 +271,16 @@ func (a *App) RecordReloadFailure() {
 	a.Metrics.ConfigReloadTotal.WithLabelValues("failure").Inc()
 }
 
+func (a *App) recordCheckScheduleMetrics(checks []config.CheckConfig) {
+	for _, c := range checks {
+		if c.UsesInterval() {
+			a.Metrics.CheckInterval.WithLabelValues(c.ID).Set(c.Interval.Duration.Seconds())
+		} else {
+			a.Metrics.CheckInterval.DeleteLabelValues(c.ID)
+		}
+	}
+}
+
 func (a *App) config() *config.Config {
 	a.cfgMu.RLock()
 	defer a.cfgMu.RUnlock()