collectors: collect payment and attempt counts

collect raw payment and attempt count information from
lnd using the TrackPayments RPC.

collectors/log.go

@@ -20,6 +20,9 @@ var (
 
 	// htlcLogger is a logger for lndmon's htlc collector.
 	htlcLogger = build.NewSubLogger("HTLC", backendLog.Logger)
+
+	// paymentLogger is a logger for lndmon's payments monitor.
+	paymentLogger = build.NewSubLogger("PMNT", backendLog.Logger)
 )
 
 // initLogRotator initializes the logging rotator to write logs to logFile and

collectors/payments_collector.go

@@ -0,0 +1,151 @@
+package collectors
+
+import (
+	"context"
+	"fmt"
+	"sync"
+
+	"github.com/lightninglabs/lndclient"
+	"github.com/lightningnetwork/lnd/lnrpc"
+	"github.com/lightningnetwork/lnd/lnrpc/routerrpc"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+var (
+	totalPayments = prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Name: "lnd_total_payments",
+			Help: "Total number of payments initiated",
+		},
+	)
+	totalHTLCAttempts = prometheus.NewCounter(
+		prometheus.CounterOpts{
+			Name: "lnd_total_htlc_attempts",
+			Help: "Total number of HTLC attempts across all payments",
+		},
+	)
+	paymentAttempts = prometheus.NewHistogram(
+		prometheus.HistogramOpts{
+			Name:    "lnd_payment_attempts_per_payment",
+			Help:    "Histogram tracking the number of attempts per payment",
+			Buckets: prometheus.LinearBuckets(1, 1, 10), // 1 to 10 attempts
+		},
+	)
+)
+
+// paymentsMonitor listens for payments and updates Prometheus metrics.
+type paymentsMonitor struct {
+	client routerrpc.RouterClient
+
+	ctx context.Context
+
+	errChan chan error
+
+	// quit is closed to signal that we need to shutdown.
+	quit chan struct{}
+
+	wg sync.WaitGroup
+}
+
+// newPaymentsMonitor creates a new payments monitor and ensures the context
+// includes macaroon authentication.
+func newPaymentsMonitor(lnd *lndclient.LndServices,
+	errChan chan error) (*paymentsMonitor, error) {
+
+	// Attach macaroon authentication for the router service.
+	ctx := context.Background()
+	ctx, err := lnd.WithMacaroonAuthForService(ctx,
+		lndclient.RouterServiceMac)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get macaroon-authenticated "+
+			"context: %w", err)
+	}
+
+	return &paymentsMonitor{
+		client:  routerrpc.NewRouterClient(lnd.ClientConn),
+		errChan: errChan,
+		quit:    make(chan struct{}),
+		ctx:     ctx,
+	}, nil
+}
+
+// start subscribes to `TrackPayments` and updates Prometheus metrics.
+func (p *paymentsMonitor) start() error {
+	// Use the stored authenticated context.
+	ctx, cancel := context.WithCancel(p.ctx)
+
+	paymentLogger.Info("Starting payments monitor...")
+
+	stream, err := p.client.TrackPayments(ctx,
+		&routerrpc.TrackPaymentsRequest{
+			// NOTE: We only need to know the final result of the
+			// payment and all attempts.
+			NoInflightUpdates: true,
+		})
+	if err != nil {
+		paymentLogger.Errorf("Failed to subscribe to TrackPayments: %v",
+			err)
+
+		cancel()
+
+		return err
+	}
+
+	p.wg.Add(1)
+	go func() {
+		defer func() {
+			cancel()
+			p.wg.Done()
+		}()
+
+		for {
+			select {
+			case <-p.quit:
+				return
+
+			default:
+				payment, err := stream.Recv()
+				if err != nil {
+					paymentLogger.Errorf("Error receiving "+
+						"payment update: %v", err)
+
+					p.errChan <- err
+					return
+				}
+				processPaymentUpdate(payment)
+			}
+		}
+	}()
+
+	return nil
+}
+
+// stop cancels the payments monitor subscription.
+func (p *paymentsMonitor) stop() {
+	paymentLogger.Info("Stopping payments monitor...")
+
+	close(p.quit)
+	p.wg.Wait()
+}
+
+// collectors returns all of the collectors that the htlc monitor uses.
+func (p *paymentsMonitor) collectors() []prometheus.Collector {
+	return []prometheus.Collector{
+		totalPayments, totalHTLCAttempts, paymentAttempts,
+	}
+}
+
+// processPaymentUpdate updates Prometheus metrics based on received payments.
+//
+// NOTE: It is expected that this receive the *final* payment update with the
+// complete list of all htlc attempts made for this payment.
+func processPaymentUpdate(payment *lnrpc.Payment) {
+	totalPayments.Inc()
+	attemptCount := len(payment.Htlcs)
+
+	totalHTLCAttempts.Add(float64(attemptCount))
+	paymentAttempts.Observe(float64(attemptCount))
+
+	paymentLogger.Debugf("Payment %s updated: %d attempts",
+		payment.PaymentHash, attemptCount)
+}

collectors/prometheus.go

@@ -32,7 +32,8 @@ type PrometheusExporter struct {
 
 	monitoringCfg *MonitoringConfig
 
-	htlcMonitor *htlcMonitor
+	htlcMonitor     *htlcMonitor
+	paymentsMonitor *paymentsMonitor
 
 	// collectors is the exporter's active set of collectors.
 	collectors []prometheus.Collector
@@ -72,6 +73,9 @@ type MonitoringConfig struct {
 	// DisableHtlc disables collection of HTLCs metrics
 	DisableHtlc bool
 
+	// DisablePayments disables collection of payment metrics
+	DisablePayments bool
+
 	// ProgramStartTime stores a best-effort estimate of when lnd/lndmon was
 	// started.
 	ProgramStartTime time.Time
@@ -100,6 +104,15 @@ func NewPrometheusExporter(cfg *PrometheusConfig, lnd *lndclient.LndServices,
 
 	htlcMonitor := newHtlcMonitor(lnd.Router, errChan)
 
+	// Create payments monitor.
+	paymentsMonitor, err := newPaymentsMonitor(lnd, errChan)
+	if err != nil {
+		paymentLogger.Errorf("Failed to initialize payment monitor: %v",
+			err)
+
+		return nil
+	}
+
 	chanCollector := NewChannelsCollector(
 		lnd.Client, errChan, quitChan, monitoringCfg,
 	)
@@ -117,19 +130,26 @@ func NewPrometheusExporter(cfg *PrometheusConfig, lnd *lndclient.LndServices,
 		collectors = append(collectors, htlcMonitor.collectors()...)
 	}
 
+	if !monitoringCfg.DisablePayments {
+		collectors = append(
+			collectors, paymentsMonitor.collectors()...,
+		)
+	}
+
 	if !monitoringCfg.DisableGraph {
 		collectors = append(
 			collectors, NewGraphCollector(lnd.Client, errChan),
 		)
 	}
 
 	return &PrometheusExporter{
-		cfg:           cfg,
-		lnd:           lnd,
-		monitoringCfg: monitoringCfg,
-		collectors:    collectors,
-		htlcMonitor:   htlcMonitor,
-		errChan:       errChan,
+		cfg:             cfg,
+		lnd:             lnd,
+		monitoringCfg:   monitoringCfg,
+		collectors:      collectors,
+		htlcMonitor:     htlcMonitor,
+		paymentsMonitor: paymentsMonitor,
+		errChan:         errChan,
 	}
 }
 
@@ -165,6 +185,15 @@ func (p *PrometheusExporter) Start() error {
 		}
 	}
 
+	// Start the payment monitor goroutine. This will subscribe to receive
+	// update for all payments made by lnd and update our payments related
+	// metrics.
+	if !p.monitoringCfg.DisablePayments {
+		if err := p.paymentsMonitor.start(); err != nil {
+			return err
+		}
+	}
+
 	// Finally, we'll launch the HTTP server that Prometheus will use to
 	// scape our metrics.
 	go func() {
@@ -199,6 +228,10 @@ func (p *PrometheusExporter) Stop() {
 	if !p.monitoringCfg.DisableHtlc {
 		p.htlcMonitor.stop()
 	}
+
+	if !p.monitoringCfg.DisablePayments {
+		p.paymentsMonitor.stop()
+	}
 }
 
 // Errors returns an error channel that any failures experienced by its

config.go

@@ -54,6 +54,9 @@ type config struct {
 
 	// DisableHtlc disables the collection of HTLCs metrics.
 	DisableHtlc bool `long:"disablehtlc" description:"Do not collect HTLCs metrics"`
+
+	// DisablePayments disables the collection of payments metrics.
+	DisablePayments bool `long:"disablepayments" description:"Do not collect payments metrics"`
 }
 
 var defaultConfig = config{

lndmon.go

@@ -63,8 +63,9 @@ func start() error {
 	defer lnd.Close()
 
 	monitoringCfg := collectors.MonitoringConfig{
-		DisableGraph: cfg.DisableGraph,
-		DisableHtlc:  cfg.DisableHtlc,
+		DisableGraph:    cfg.DisableGraph,
+		DisableHtlc:     cfg.DisableHtlc,
+		DisablePayments: cfg.DisablePayments,
 	}
 	if cfg.PrimaryNode != "" {
 		primaryNode, err := route.NewVertexFromStr(cfg.PrimaryNode)