Refactor NewAlertmanager() to not register new instance by default

This makes it easier to test code

internal/alertmanager/dedup_test.go

@@ -17,7 +17,8 @@ func init() {
 	log.SetLevel(log.ErrorLevel)
 	for i, uri := range mock.ListAllMockURIs() {
 		name := fmt.Sprintf("dedup-mock-%d", i)
-		alertmanager.NewAlertmanager(name, uri, alertmanager.WithRequestTimeout(time.Second))
+		am := alertmanager.NewAlertmanager(name, uri, alertmanager.WithRequestTimeout(time.Second))
+		alertmanager.RegisterAlertmanager(am)
 	}
 }
 

internal/alertmanager/upstream.go

@@ -18,17 +18,7 @@ var (
 )
 
 // NewAlertmanager creates a new Alertmanager instance
-func NewAlertmanager(name, uri string, opts ...Option) error {
-	if _, found := upstreams[name]; found {
-		return fmt.Errorf("Alertmanager upstream '%s' already exist", name)
-	}
-
-	for _, am := range upstreams {
-		if am.URI == uri {
-			return fmt.Errorf("Alertmanager upstream '%s' already collects from '%s'", am.Name, am.URI)
-		}
-	}
-
+func NewAlertmanager(name, uri string, opts ...Option) *Alertmanager {
 	am := &Alertmanager{
 		URI:            uri,
 		RequestTimeout: time.Second * 10,
@@ -50,10 +40,23 @@ func NewAlertmanager(name, uri string, opts ...Option) error {
 		opt(am)
 	}
 
-	upstreams[name] = am
+	return am
+}
 
-	log.Infof("[%s] Configured Alertmanager source at %s", name, uri)
+// RegisterAlertmanager will add an Alertmanager instance to the list of
+// instances used when pulling alerts from upstreams
+func RegisterAlertmanager(am *Alertmanager) error {
+	if _, found := upstreams[am.Name]; found {
+		return fmt.Errorf("Alertmanager upstream '%s' already exist", am.Name)
+	}
 
+	for _, existingAM := range upstreams {
+		if existingAM.URI == am.URI {
+			return fmt.Errorf("Alertmanager upstream '%s' already collects from '%s'", existingAM.Name, existingAM.URI)
+		}
+	}
+	upstreams[am.Name] = am
+	log.Infof("[%s] Configured Alertmanager source at %s (proxied: %v)", am.Name, am.URI, am.ProxyRequests)
 	return nil
 }
 

internal/filters/filter_test.go

@@ -485,11 +485,7 @@ var tests = []filterTest{
 func TestFilters(t *testing.T) {
 	log.SetLevel(log.ErrorLevel)
 
-	err := alertmanager.NewAlertmanager("test", "http://localhost", alertmanager.WithRequestTimeout(time.Second))
-	am := alertmanager.GetAlertmanagerByName("test")
-	if err != nil {
-		t.Error(err)
-	}
+	am := alertmanager.NewAlertmanager("test", "http://localhost", alertmanager.WithRequestTimeout(time.Second))
 	for _, ft := range tests {
 		alert := models.Alert(ft.Alert)
 		if &ft.Silence != nil {

main.go

@@ -60,8 +60,8 @@ func setupRouter(router *gin.Engine) {
 
 func setupUpstreams() {
 	for _, s := range config.Config.Alertmanager.Servers {
-		var err error
-		err = alertmanager.NewAlertmanager(s.Name, s.URI, alertmanager.WithRequestTimeout(s.Timeout), alertmanager.WithProxy(s.Proxy))
+		am := alertmanager.NewAlertmanager(s.Name, s.URI, alertmanager.WithRequestTimeout(s.Timeout), alertmanager.WithProxy(s.Proxy))
+		err := alertmanager.RegisterAlertmanager(am)
 		if err != nil {
 			log.Fatalf("Failed to configure Alertmanager '%s' with URI '%s': %s", s.Name, s.URI, err)
 		}

proxy_test.go

@@ -90,12 +90,13 @@ var proxyTests = []proxyTest{
 
 func TestProxy(t *testing.T) {
 	r := ginTestEngine()
-	setupRouterProxyHandlers(r, &alertmanager.Alertmanager{
-		URI:            "http://localhost:9093",
-		RequestTimeout: time.Second * 5,
-		Name:           "dummy",
-		ProxyRequests:  true,
-	})
+	am := alertmanager.NewAlertmanager(
+		"dummy",
+		"http://localhost:9093",
+		alertmanager.WithRequestTimeout(time.Second*5),
+		alertmanager.WithProxy(true),
+	)
+	setupRouterProxyHandlers(r, am)
 
 	httpmock.Activate()
 	defer httpmock.DeactivateAndReset()