From 331ad3140148e053da87441c1bb006aa9a81f68c Mon Sep 17 00:00:00 2001
From: Fabian Reinartz <fab.reinartz@gmail.com>
Date: Tue, 29 Sep 2015 12:22:13 +0200
Subject: [PATCH] Implement configuration reloading

---
 dispatch.go          |  4 +++-
 inhibit.go           |  4 +++-
 main.go              | 42 +++++++++++++++++++++++++++++++++---------
 notify.go            |  4 +++-
 provider/provider.go |  9 +--------
 types/types.go       |  8 ++++++++
 6 files changed, 51 insertions(+), 20 deletions(-)

diff --git a/dispatch.go b/dispatch.go
index ea9aec03..27fb358f 100644
--- a/dispatch.go
+++ b/dispatch.go
@@ -43,7 +43,7 @@ func NewDispatcher(ap provider.Alerts, n Notifier) *Dispatcher {
 }
 
 // ApplyConfig updates the dispatcher to match the new configuration.
-func (d *Dispatcher) ApplyConfig(conf *config.Config) {
+func (d *Dispatcher) ApplyConfig(conf *config.Config) bool {
 	d.mtx.Lock()
 	defer d.mtx.Unlock()
 
@@ -54,6 +54,8 @@ func (d *Dispatcher) ApplyConfig(conf *config.Config) {
 	}
 
 	d.routes = NewRoutes(conf.Routes)
+
+	return true
 }
 
 // Run starts dispatching alerts incoming via the updates channel.
diff --git a/inhibit.go b/inhibit.go
index 4d30449b..bbf8add9 100644
--- a/inhibit.go
+++ b/inhibit.go
@@ -42,7 +42,7 @@ func (ih *Inhibitor) Mutes(lset model.LabelSet) bool {
 	return false
 }
 
-func (ih *Inhibitor) ApplyConfig(conf *config.Config) {
+func (ih *Inhibitor) ApplyConfig(conf *config.Config) bool {
 	ih.mtx.Lock()
 	defer ih.mtx.Unlock()
 
@@ -50,6 +50,8 @@ func (ih *Inhibitor) ApplyConfig(conf *config.Config) {
 	for _, cr := range conf.InhibitRules {
 		ih.rules = append(ih.rules, NewInhibitRule(cr))
 	}
+
+	return true
 }
 
 // An InhibitRule specifies that a class of (source) alerts should inhibit
diff --git a/main.go b/main.go
index c198349f..7ef943f6 100644
--- a/main.go
+++ b/main.go
@@ -25,6 +25,7 @@ import (
 
 	"github.com/prometheus/alertmanager/config"
 	"github.com/prometheus/alertmanager/provider"
+	"github.com/prometheus/alertmanager/types"
 )
 
 var (
@@ -34,11 +35,6 @@ var (
 func main() {
 	flag.Parse()
 
-	conf, err := config.LoadFile(*configFile)
-	if err != nil {
-		log.Fatal(err)
-	}
-
 	data := provider.NewMemData()
 
 	alerts := provider.NewMemAlerts(data)
@@ -46,7 +42,6 @@ func main() {
 	silences := provider.NewMemSilences()
 
 	inhibitor := &Inhibitor{alerts: alerts}
-	inhibitor.ApplyConfig(conf)
 
 	routedNotifier := newRoutedNotifier(func(conf *config.Config) map[string]Notifier {
 		res := map[string]Notifier{}
@@ -55,7 +50,6 @@ func main() {
 		}
 		return res
 	})
-	routedNotifier.ApplyConfig(conf)
 
 	var notifier Notifier
 	notifier = routedNotifier
@@ -70,7 +64,10 @@ func main() {
 
 	disp := NewDispatcher(alerts, notifier)
 
-	disp.ApplyConfig(conf)
+	if !reloadConfig(*configFile, disp, routedNotifier, inhibitor) {
+		os.Exit(1)
+	}
+
 	go disp.Run()
 	defer disp.Stop()
 
@@ -80,10 +77,37 @@ func main() {
 
 	go http.ListenAndServe(":9091", router)
 
-	term := make(chan os.Signal)
+	var (
+		hup  = make(chan os.Signal)
+		term = make(chan os.Signal)
+	)
+	signal.Notify(hup, syscall.SIGHUP)
 	signal.Notify(term, os.Interrupt, syscall.SIGTERM)
+
+	go func() {
+		for range hup {
+			reloadConfig(*configFile, disp, routedNotifier, inhibitor)
+		}
+	}()
+
 	<-term
 
 	log.Infoln("Received SIGTERM, exiting gracefully...")
 	os.Exit(0)
 }
+
+func reloadConfig(filename string, rls ...types.Reloadable) (success bool) {
+	log.Infof("Loading configuration file %s", filename)
+
+	conf, err := config.LoadFile(filename)
+	if err != nil {
+		log.Errorf("Couldn't load configuration (-config.file=%s): %v", filename, err)
+		return false
+	}
+	success = true
+
+	for _, rl := range rls {
+		success = success && rl.ApplyConfig(conf)
+	}
+	return success
+}
diff --git a/notify.go b/notify.go
index 4c249923..dce8e7fe 100644
--- a/notify.go
+++ b/notify.go
@@ -150,7 +150,7 @@ func (n *routedNotifier) Notify(ctx context.Context, alerts ...*types.Alert) err
 	return notifier.Notify(ctx, alerts...)
 }
 
-func (n *routedNotifier) ApplyConfig(conf *config.Config) {
+func (n *routedNotifier) ApplyConfig(conf *config.Config) bool {
 	n.mtx.Lock()
 	defer n.mtx.Unlock()
 
@@ -160,6 +160,8 @@ func (n *routedNotifier) ApplyConfig(conf *config.Config) {
 	for _, opts := range conf.NotificationConfigs {
 		n.notifierOpts[opts.Name] = opts
 	}
+
+	return true
 }
 
 // mutingNotifier wraps a notifier and applies a Silencer
diff --git a/provider/provider.go b/provider/provider.go
index 4f0b836f..ef9324a4 100644
--- a/provider/provider.go
+++ b/provider/provider.go
@@ -16,7 +16,6 @@ package provider
 import (
 	"github.com/prometheus/common/model"
 
-	"github.com/prometheus/alertmanager/config"
 	"github.com/prometheus/alertmanager/types"
 )
 
@@ -70,13 +69,7 @@ type Notifies interface {
 	Set(dest string, ns ...*types.Notify) error
 }
 
-// Reloadable is a component that can change its state based
-// on a new configuration.
-type Reloadable interface {
-	ApplyConfig(*config.Config)
-}
-
 type Config interface {
 	// Reload initiates a configuration reload.
-	Reload(...Reloadable) error
+	Reload(...types.Reloadable) error
 }
diff --git a/types/types.go b/types/types.go
index fe3b9def..b556a6d7 100644
--- a/types/types.go
+++ b/types/types.go
@@ -7,8 +7,16 @@ import (
 	"time"
 
 	"github.com/prometheus/common/model"
+
+	"github.com/prometheus/alertmanager/config"
 )
 
+// Reloadable is a component that can change its state based
+// on a new configuration.
+type Reloadable interface {
+	ApplyConfig(*config.Config) bool
+}
+
 type Annotations map[model.LabelName]string
 
 type Alert struct {