Add api/-/reload endpoint #353

api.go

@@ -58,6 +58,7 @@ type API struct {
 	config         string
 	resolveTimeout time.Duration
 	uptime         time.Time
+	reloadCh       chan struct{}
 
 	groups func() AlertOverview
 
@@ -74,6 +75,7 @@ func NewAPI(alerts provider.Alerts, silences provider.Silences, gf func() AlertO
 		silences: silences,
 		groups:   gf,
 		uptime:   time.Now(),
+		reloadCh: make(chan struct{}),
 	}
 }
 
@@ -82,6 +84,9 @@ func NewAPI(alerts provider.Alerts, silences provider.Silences, gf func() AlertO
 func (api *API) Register(r *route.Router) {
 	ihf := prometheus.InstrumentHandlerFunc
 
+	// Register reload API for reload configuration.
+	r.Post("/-/reload", api.reload)
+
 	// Register legacy forwarder for alert pushing.
 	r.Post("/alerts", ihf("legacy_add_alerts", api.legacyAddAlerts))
 
@@ -109,6 +114,11 @@ func (api *API) Update(config string, resolveTimeout time.Duration) {
 	api.resolveTimeout = resolveTimeout
 }
 
+// Reload returns the receive-only channel that signals configuration reload requests.
+func (api *API) Reload() <-chan struct{} {
+	return api.reloadCh
+}
+
 type errorType string
 
 const (
@@ -373,6 +383,11 @@ func (api *API) listSilences(w http.ResponseWriter, r *http.Request) {
 	respond(w, sils)
 }
 
+func (api *API) reload(w http.ResponseWriter, r *http.Request) {
+	fmt.Fprintf(w, "Reloading configuration file...")
+	api.reloadCh <- struct{}{}
+}
+
 type status string
 
 const (

main.go

@@ -194,18 +194,27 @@ func main() {
 	go listen(router)
 
 	var (
-		hup  = make(chan os.Signal)
-		term = make(chan os.Signal)
+		hup      = make(chan os.Signal)
+		hupReady = make(chan bool)
+		term     = make(chan os.Signal)
 	)
 	signal.Notify(hup, syscall.SIGHUP)
 	signal.Notify(term, os.Interrupt, syscall.SIGTERM)
 
 	go func() {
-		for range hup {
+		<-hupReady
+		for {
+			select {
+			case <-hup:
+			case <-api.Reload():
+			}
 			reload()
 		}
 	}()
 
+	// Wait for reload or termination signals.
+	close(hupReady) // Unblock SIGHUP handler.
+
 	<-term
 
 	log.Infoln("Received SIGTERM, exiting gracefully...")