main.go: Move marker metric registering into types/types.go

Instead of registering marker metrics inside of
cmd/alertmanager/main.go, register them in types/types.go, encapsulating
marker specific logic in its module, not in main.go. In addition it
paves the path for removing the usage of the global metric registry in
the future, by taking a local metric registerer.

Signed-off-by: Max Leonard Inden <IndenML@gmail.com>

cmd/alertmanager/main.go

@@ -67,8 +67,6 @@ var (
 		Name: "alertmanager_config_last_reload_success_timestamp_seconds",
 		Help: "Timestamp of the last successful configuration reload.",
 	})
-	alertsActive     prometheus.GaugeFunc
-	alertsSuppressed prometheus.GaugeFunc
 	requestDuration = prometheus.NewHistogramVec(
 		prometheus.HistogramOpts{
 			Name:    "alertmanager_http_request_duration_seconds",
@@ -107,27 +105,6 @@ func instrumentHandler(handlerName string, handler http.HandlerFunc) http.Handle
 	)
 }
 
-func newAlertMetricByState(marker types.Marker, st types.AlertState) prometheus.GaugeFunc {
-	return prometheus.NewGaugeFunc(
-		prometheus.GaugeOpts{
-			Name:        "alertmanager_alerts",
-			Help:        "How many alerts by state.",
-			ConstLabels: prometheus.Labels{"state": string(st)},
-		},
-		func() float64 {
-			return float64(marker.Count(st))
-		},
-	)
-}
-
-func newMarkerMetrics(marker types.Marker) {
-	alertsActive = newAlertMetricByState(marker, types.AlertStateActive)
-	alertsSuppressed = newAlertMetricByState(marker, types.AlertStateSuppressed)
-
-	prometheus.MustRegister(alertsActive)
-	prometheus.MustRegister(alertsSuppressed)
-}
-
 const defaultClusterAddr = "0.0.0.0:9094"
 
 func main() {
@@ -225,8 +202,7 @@ func run() int {
 		notificationLog.SetBroadcast(c.Broadcast)
 	}
 
-	marker := types.NewMarker()
-	newMarkerMetrics(marker)
+	marker := types.NewMarker(prometheus.DefaultRegisterer)
 
 	silenceOpts := silence.Options{
 		SnapshotFile: filepath.Join(*dataDir, "silences"),

inhibit/inhibit_test.go

@@ -18,6 +18,7 @@ import (
 	"time"
 
 	"github.com/go-kit/kit/log"
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/common/model"
 
 	"github.com/prometheus/alertmanager/config"
@@ -145,7 +146,7 @@ func TestInhibitRuleMatches(t *testing.T) {
 		TargetMatch: map[string]string{"t": "1"},
 		Equal:       model.LabelNames{"e"},
 	}
-	m := types.NewMarker()
+	m := types.NewMarker(prometheus.NewRegistry())
 	ih := NewInhibitor(nil, []*config.InhibitRule{&cr}, m, nopLogger)
 	ir := ih.rules[0]
 	now := time.Now()
@@ -320,7 +321,7 @@ func TestInhibit(t *testing.T) {
 		},
 	} {
 		ap := newFakeAlerts(tc.alerts)
-		mk := types.NewMarker()
+		mk := types.NewMarker(prometheus.NewRegistry())
 		inhibitor := NewInhibitor(ap, []*config.InhibitRule{inhibitRule()}, mk, nopLogger)
 
 		go func() {

notify/notify_test.go

@@ -22,6 +22,7 @@ import (
 	"time"
 
 	"github.com/go-kit/kit/log"
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/common/model"
 	"github.com/stretchr/testify/require"
 
@@ -586,7 +587,7 @@ func TestSilenceStage(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	marker := types.NewMarker()
+	marker := types.NewMarker(prometheus.NewRegistry())
 	silencer := NewSilenceStage(silences, marker)
 
 	in := []model.LabelSet{

provider/mem/mem_test.go

@@ -27,6 +27,7 @@ import (
 	"github.com/kylelemons/godebug/pretty"
 	"github.com/prometheus/alertmanager/store"
 	"github.com/prometheus/alertmanager/types"
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/common/model"
 	"github.com/stretchr/testify/require"
 )
@@ -83,7 +84,7 @@ func init() {
 // If the channel of a listener is at its limit, `alerts.Lock` is blocked, whereby
 // a listener can not unsubscribe as the lock is hold by `alerts.Lock`.
 func TestAlertsSubscribePutStarvation(t *testing.T) {
-	marker := types.NewMarker()
+	marker := types.NewMarker(prometheus.NewRegistry())
 	alerts, err := NewAlerts(context.Background(), marker, 30*time.Minute, log.NewNopLogger())
 	if err != nil {
 		t.Fatal(err)
@@ -134,7 +135,7 @@ func TestAlertsSubscribePutStarvation(t *testing.T) {
 }
 
 func TestAlertsPut(t *testing.T) {
-	marker := types.NewMarker()
+	marker := types.NewMarker(prometheus.NewRegistry())
 	alerts, err := NewAlerts(context.Background(), marker, 30*time.Minute, log.NewNopLogger())
 	if err != nil {
 		t.Fatal(err)
@@ -159,7 +160,7 @@ func TestAlertsPut(t *testing.T) {
 }
 
 func TestAlertsSubscribe(t *testing.T) {
-	marker := types.NewMarker()
+	marker := types.NewMarker(prometheus.NewRegistry())
 	alerts, err := NewAlerts(context.Background(), marker, 30*time.Minute, log.NewNopLogger())
 	if err != nil {
 		t.Fatal(err)
@@ -248,7 +249,7 @@ func TestAlertsSubscribe(t *testing.T) {
 }
 
 func TestAlertsGetPending(t *testing.T) {
-	marker := types.NewMarker()
+	marker := types.NewMarker(prometheus.NewRegistry())
 	alerts, err := NewAlerts(context.Background(), marker, 30*time.Minute, log.NewNopLogger())
 	if err != nil {
 		t.Fatal(err)
@@ -291,7 +292,7 @@ func TestAlertsGetPending(t *testing.T) {
 }
 
 func TestAlertsGC(t *testing.T) {
-	marker := types.NewMarker()
+	marker := types.NewMarker(prometheus.NewRegistry())
 	alerts, err := NewAlerts(context.Background(), marker, 200*time.Millisecond, log.NewNopLogger())
 	if err != nil {
 		t.Fatal(err)

types/types.go

@@ -18,6 +18,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/common/model"
 )
 
@@ -55,10 +56,14 @@ type Marker interface {
 }
 
 // NewMarker returns an instance of a Marker implementation.
-func NewMarker() Marker {
-	return &memMarker{
+func NewMarker(r prometheus.Registerer) Marker {
+	m := &memMarker{
 		m: map[model.Fingerprint]*AlertStatus{},
 	}
+
+	m.registerMetrics(r)
+
+	return m
 }
 
 type memMarker struct {
@@ -67,6 +72,27 @@ type memMarker struct {
 	mtx sync.RWMutex
 }
 
+func (m *memMarker) registerMetrics(r prometheus.Registerer) {
+	newAlertMetricByState := func(st AlertState) prometheus.GaugeFunc {
+		return prometheus.NewGaugeFunc(
+			prometheus.GaugeOpts{
+				Name:        "alertmanager_alerts",
+				Help:        "How many alerts by state.",
+				ConstLabels: prometheus.Labels{"state": string(st)},
+			},
+			func() float64 {
+				return float64(m.Count(st))
+			},
+		)
+	}
+
+	alertsActive := newAlertMetricByState(AlertStateActive)
+	alertsSuppressed := newAlertMetricByState(AlertStateSuppressed)
+
+	r.MustRegister(alertsActive)
+	r.MustRegister(alertsSuppressed)
+}
+
 // Count alerts of a given state.
 func (m *memMarker) Count(states ...AlertState) int {
 	count := 0

types/types_test.go

@@ -20,6 +20,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/common/model"
 	"github.com/stretchr/testify/require"
 )
@@ -366,3 +367,28 @@ func TestAlertSliceSort(t *testing.T) {
 		}
 	}
 }
+
+type fakeRegisterer struct {
+	registeredCollectors []prometheus.Collector
+}
+
+func (r *fakeRegisterer) Register(prometheus.Collector) error {
+	return nil
+}
+
+func (r *fakeRegisterer) MustRegister(c ...prometheus.Collector) {
+	r.registeredCollectors = append(r.registeredCollectors, c...)
+}
+
+func (r *fakeRegisterer) Unregister(prometheus.Collector) bool {
+	return false
+}
+
+func TestNewMarkerRegistersMetrics(t *testing.T) {
+	fr := fakeRegisterer{}
+	NewMarker(&fr)
+
+	if len(fr.registeredCollectors) == 0 {
+		t.Error("expected NewMarker to register metrics on the given registerer")
+	}
+}