cmd/alermanager: log when repeat_interval > retention (#1993)

Signed-off-by: Simon Pasquier <spasquie@redhat.com>

cmd/alertmanager/main.go

@@ -157,6 +157,18 @@ func buildReceiverIntegrations(nc *config.Receiver, tmpl *template.Template, log
 	}
 	return integrations, nil
 }
+
+// walkRoute traverses the route tree in depth-first order.
+func walkRoute(r *dispatch.Route, visit func(*dispatch.Route)) {
+	visit(r)
+	if r.Routes == nil {
+		return
+	}
+	for i := range r.Routes {
+		walkRoute(r.Routes[i], visit)
+	}
+}
+
 func main() {
 	os.Exit(run())
 }
@@ -401,7 +413,22 @@ func run() int {
 			silencer.Mutes(labels)
 		})
 
-		disp = dispatch.NewDispatcher(alerts, dispatch.NewRoute(conf.Route, nil), pipeline, marker, timeoutFunc, logger)
+		routes := dispatch.NewRoute(conf.Route, nil)
+		disp = dispatch.NewDispatcher(alerts, routes, pipeline, marker, timeoutFunc, logger)
+		walkRoute(routes, func(r *dispatch.Route) {
+			if r.RouteOpts.RepeatInterval > *retention {
+				level.Warn(log.With(logger, "component", "configuration")).Log(
+					"msg",
+					"repeat_interval is greater than the data retention period. It can lead to notifications being repeated more often than expected.",
+					"repeat_interval",
+					r.RouteOpts.RepeatInterval,
+					"retention",
+					*retention,
+					"route",
+					r.Key(),
+				)
+			}
+		})
 
 		go disp.Run()
 		go inhibitor.Run()