Merge pull request #2465 from Gouthamve/alert-metrics-2429

Better Metrics For Alerts

cmd/prometheus/config.go

@@ -26,6 +26,7 @@ import (
 	"unicode"
 
 	"github.com/asaskevich/govalidator"
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/common/log"
 	"github.com/prometheus/common/model"
 	"github.com/prometheus/prometheus/config"
@@ -60,6 +61,9 @@ var cfg = struct {
 	deprecatedMaxChunksToPersist uint64
 }{
 	alertmanagerURLs: stringset{},
+	notifier: notifier.Options{
+		Registerer: prometheus.DefaultRegisterer,
+	},
 }
 
 // Value type for flags that are now unused, but which are kept around to

cmd/prometheus/main.go

@@ -203,7 +203,6 @@ func Main() int {
 	if instrumentedStorage, ok := localStorage.(prometheus.Collector); ok {
 		prometheus.MustRegister(instrumentedStorage)
 	}
-	prometheus.MustRegister(notifier)
 	prometheus.MustRegister(configSuccess)
 	prometheus.MustRegister(configSuccessTime)
 

notifier/notifier.go

@@ -56,18 +56,13 @@ type Notifier struct {
 	queue model.Alerts
 	opts  *Options
 
+	metrics *alertMetrics
+
 	more   chan struct{}
 	mtx    sync.RWMutex
 	ctx    context.Context
 	cancel func()
 
-	latency       *prometheus.SummaryVec
-	errors        *prometheus.CounterVec
-	sent          *prometheus.CounterVec
-	dropped       prometheus.Counter
-	queueLength   prometheus.Gauge
-	queueCapacity prometheus.Metric
-
 	alertmanagers   []*alertmanagerSet
 	cancelDiscovery func()
 }
@@ -79,23 +74,21 @@ type Options struct {
 	RelabelConfigs []*config.RelabelConfig
 	// Used for sending HTTP requests to the Alertmanager.
 	Do func(ctx context.Context, client *http.Client, req *http.Request) (*http.Response, error)
+
+	Registerer prometheus.Registerer
 }
 
-// New constructs a new Notifier.
-func New(o *Options) *Notifier {
-	ctx, cancel := context.WithCancel(context.Background())
-
-	if o.Do == nil {
-		o.Do = ctxhttp.Do
-	}
-
-	return &Notifier{
-		queue:  make(model.Alerts, 0, o.QueueCapacity),
-		ctx:    ctx,
-		cancel: cancel,
-		more:   make(chan struct{}, 1),
-		opts:   o,
+type alertMetrics struct {
+	latency       *prometheus.SummaryVec
+	errors        *prometheus.CounterVec
+	sent          *prometheus.CounterVec
+	dropped       prometheus.Counter
+	queueLength   prometheus.GaugeFunc
+	queueCapacity prometheus.Gauge
+}
 
+func newAlertMetrics(r prometheus.Registerer, queueCap int, queueLen func() float64) *alertMetrics {
+	m := &alertMetrics{
 		latency: prometheus.NewSummaryVec(prometheus.SummaryOpts{
 			Namespace: namespace,
 			Subsystem: subsystem,
@@ -126,22 +119,55 @@ func New(o *Options) *Notifier {
 			Name:      "dropped_total",
 			Help:      "Total number of alerts dropped due to errors when sending to Alertmanager.",
 		}),
-		queueLength: prometheus.NewGauge(prometheus.GaugeOpts{
+		queueLength: prometheus.NewGaugeFunc(prometheus.GaugeOpts{
 			Namespace: namespace,
 			Subsystem: subsystem,
 			Name:      "queue_length",
 			Help:      "The number of alert notifications in the queue.",
+		}, queueLen),
+		queueCapacity: prometheus.NewGauge(prometheus.GaugeOpts{
+			Namespace: namespace,
+			Subsystem: subsystem,
+			Name:      "queue_capacity",
+			Help:      "The capacity of the alert notifications queue.",
 		}),
-		queueCapacity: prometheus.MustNewConstMetric(
-			prometheus.NewDesc(
-				prometheus.BuildFQName(namespace, subsystem, "queue_capacity"),
-				"The capacity of the alert notifications queue.",
-				nil, nil,
-			),
-			prometheus.GaugeValue,
-			float64(o.QueueCapacity),
-		),
 	}
+
+	m.queueCapacity.Set(float64(queueCap))
+
+	if r != nil {
+		r.MustRegister(
+			m.latency,
+			m.errors,
+			m.sent,
+			m.dropped,
+			m.queueLength,
+			m.queueCapacity,
+		)
+	}
+
+	return m
+}
+
+// New constructs a new Notifier.
+func New(o *Options) *Notifier {
+	ctx, cancel := context.WithCancel(context.Background())
+
+	if o.Do == nil {
+		o.Do = ctxhttp.Do
+	}
+
+	n := &Notifier{
+		queue:  make(model.Alerts, 0, o.QueueCapacity),
+		ctx:    ctx,
+		cancel: cancel,
+		more:   make(chan struct{}, 1),
+		opts:   o,
+	}
+
+	queueLenFunc := func() float64 { return float64(n.queueLen()) }
+	n.metrics = newAlertMetrics(o.Registerer, o.QueueCapacity, queueLenFunc)
+	return n
 }
 
 // ApplyConfig updates the status state as the new config requires.
@@ -160,6 +186,9 @@ func (n *Notifier) ApplyConfig(conf *config.Config) error {
 		if err != nil {
 			return err
 		}
+
+		ams.metrics = n.metrics
+
 		amSets = append(amSets, ams)
 	}
 
@@ -216,7 +245,7 @@ func (n *Notifier) Run() {
 		alerts := n.nextBatch()
 
 		if !n.sendAll(alerts...) {
-			n.dropped.Add(float64(len(alerts)))
+			n.metrics.dropped.Add(float64(len(alerts)))
 		}
 		// If the queue still has items left, kick off the next iteration.
 		if n.queueLen() > 0 {
@@ -248,7 +277,7 @@ func (n *Notifier) Send(alerts ...*model.Alert) {
 		alerts = alerts[d:]
 
 		log.Warnf("Alert batch larger than queue capacity, dropping %d alerts", d)
-		n.dropped.Add(float64(d))
+		n.metrics.dropped.Add(float64(d))
 	}
 
 	// If the queue is full, remove the oldest alerts in favor
@@ -257,7 +286,7 @@ func (n *Notifier) Send(alerts ...*model.Alert) {
 		n.queue = n.queue[d:]
 
 		log.Warnf("Alert notification queue full, dropping %d alerts", d)
-		n.dropped.Add(float64(d))
+		n.metrics.dropped.Add(float64(d))
 	}
 	n.queue = append(n.queue, alerts...)
 
@@ -339,12 +368,12 @@ func (n *Notifier) sendAll(alerts ...*model.Alert) bool {
 
 				if err := n.sendOne(ctx, ams.client, u, b); err != nil {
 					log.With("alertmanager", u).With("count", len(alerts)).Errorf("Error sending alerts: %s", err)
-					n.errors.WithLabelValues(u).Inc()
+					n.metrics.errors.WithLabelValues(u).Inc()
 				} else {
 					atomic.AddUint64(&numSuccess, 1)
 				}
-				n.latency.WithLabelValues(u).Observe(time.Since(begin).Seconds())
-				n.sent.WithLabelValues(u).Add(float64(len(alerts)))
+				n.metrics.latency.WithLabelValues(u).Observe(time.Since(begin).Seconds())
+				n.metrics.sent.WithLabelValues(u).Add(float64(len(alerts)))
 
 				wg.Done()
 			}(am)
@@ -381,30 +410,6 @@ func (n *Notifier) Stop() {
 	n.cancel()
 }
 
-// Describe implements prometheus.Collector.
-func (n *Notifier) Describe(ch chan<- *prometheus.Desc) {
-	n.latency.Describe(ch)
-	n.errors.Describe(ch)
-	n.sent.Describe(ch)
-
-	ch <- n.dropped.Desc()
-	ch <- n.queueLength.Desc()
-	ch <- n.queueCapacity.Desc()
-}
-
-// Collect implements prometheus.Collector.
-func (n *Notifier) Collect(ch chan<- prometheus.Metric) {
-	n.queueLength.Set(float64(n.queueLen()))
-
-	n.latency.Collect(ch)
-	n.errors.Collect(ch)
-	n.sent.Collect(ch)
-
-	ch <- n.dropped
-	ch <- n.queueLength
-	ch <- n.queueCapacity
-}
-
 // alertmanager holds Alertmanager endpoint information.
 type alertmanager interface {
 	url() string
@@ -430,6 +435,8 @@ type alertmanagerSet struct {
 	cfg    *config.AlertmanagerConfig
 	client *http.Client
 
+	metrics *alertMetrics
+
 	mtx sync.RWMutex
 	ams []alertmanager
 }
@@ -474,6 +481,10 @@ func (s *alertmanagerSet) Sync(tgs []*config.TargetGroup) {
 			continue
 		}
 
+		// This will initialise the Counters for the AM to 0.
+		s.metrics.sent.WithLabelValues(us)
+		s.metrics.errors.WithLabelValues(us)
+
 		seen[us] = struct{}{}
 		s.ams = append(s.ams, am)
 	}