Add prometheus hook to count different log levels (#67)

* Add hook for logging errors and warnings

* Check log metrics value in integration test

* Update metrics_test.go

* Update metrics_test.go

* Update metrics_test.go

cmd/soroban-rpc/internal/daemon/metrics.go

@@ -2,6 +2,7 @@ package daemon
 
 import (
 	"context"
+	supportlog "github.com/stellar/go/support/log"
 	"runtime"
 	"time"
 
@@ -16,13 +17,17 @@ import (
 )
 
 func (d *Daemon) registerMetrics() {
+	// LogMetricsHook is a metric which counts log lines emitted by soroban rpc
+	logMetricsHook := logmetrics.New(prometheusNamespace)
+	d.logger.AddHook(logMetricsHook)
+	for _, counter := range logMetricsHook {
+		d.metricsRegistry.MustRegister(counter)
+	}
+
 	buildInfoGauge := prometheus.NewGaugeVec(
 		prometheus.GaugeOpts{Namespace: prometheusNamespace, Subsystem: "build", Name: "info"},
 		[]string{"version", "goversion", "commit", "branch", "build_timestamp"},
 	)
-	// LogMetricsHook is a metric which counts log lines emitted by soroban rpc
-	LogMetricsHook := logmetrics.New(prometheusNamespace)
-	//
 	buildInfoGauge.With(prometheus.Labels{
 		"version":         config.Version,
 		"commit":          config.CommitHash,
@@ -34,10 +39,6 @@ func (d *Daemon) registerMetrics() {
 	d.metricsRegistry.MustRegister(prometheus.NewGoCollector())
 	d.metricsRegistry.MustRegister(prometheus.NewProcessCollector(prometheus.ProcessCollectorOpts{}))
 	d.metricsRegistry.MustRegister(buildInfoGauge)
-
-	for _, counter := range LogMetricsHook {
-		d.metricsRegistry.MustRegister(counter)
-	}
 }
 
 func (d *Daemon) MetricsRegistry() *prometheus.Registry {
@@ -102,3 +103,7 @@ func (c *CoreClientWithMetrics) SubmitTransaction(ctx context.Context, envelopeB
 func (d *Daemon) CoreClient() interfaces.CoreClient {
 	return d.coreClient
 }
+
+func (d *Daemon) Logger() *supportlog.Entry {
+	return d.logger
+}

cmd/soroban-rpc/internal/test/metrics_test.go

@@ -2,6 +2,9 @@ package test
 
 import (
 	"fmt"
+	io_prometheus_client "github.com/prometheus/client_model/go"
+	"github.com/stellar/go/support/errors"
+	"github.com/stretchr/testify/assert"
 	"io"
 	"net/http"
 	"net/url"
@@ -25,6 +28,24 @@ func TestMetrics(t *testing.T) {
 		config.Version,
 	)
 	require.Contains(t, metrics, buildMetric)
+
+	logger := test.daemon.Logger()
+	err := errors.Errorf("test-error")
+	logger.WithError(err).Error("test error 1")
+	logger.WithError(err).Error("test error 2")
+
+	metricFamilies, err := test.daemon.MetricsRegistry().Gather()
+	assert.NoError(t, err)
+	var metric *io_prometheus_client.MetricFamily
+	for _, mf := range metricFamilies {
+		if *mf.Name == "soroban_rpc_log_error_total" {
+			metric = mf
+			break
+		}
+	}
+	assert.NotNil(t, metric)
+	val := metric.Metric[0].Counter.GetValue()
+	assert.GreaterOrEqual(t, val, 2.0)
 }
 
 func getMetrics(test *Test) string {