add additional goroutine metrics (#158)

Co-authored-by: Rick Bijkerk <[email protected]>

Author: rickbijkerk

cmd/serve.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"github.com/ldebruijn/graphql-protect/internal/app/config"
+	_ "github.com/ldebruijn/graphql-protect/internal/app/metrics"
 	"github.com/ldebruijn/graphql-protect/internal/app/otel"
 	"github.com/ldebruijn/graphql-protect/internal/business/protect"
 	"github.com/ldebruijn/graphql-protect/internal/business/rules/block_field_suggestions"

internal/app/metrics/metrics.go

@@ -0,0 +1,27 @@
+package metrics
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/collectors"
+	"regexp"
+)
+
+func init() {
+	// Register metrics from GoCollector collecting statistics from the Go Runtime.
+	// This enabled default, recommended metrics with the additional, recommended metric for
+	// goroutine scheduling latencies histogram that is currently bit too expensive for the default option.
+	//
+	// See the related GopherConUK talk to learn more: https://www.youtube.com/watch?v=18dyI_8VFa0
+
+	// Unregister the default GoCollector.
+	prometheus.Unregister(collectors.NewGoCollector())
+
+	// Register the default GoCollector with a custom config.
+	prometheus.MustRegister(
+		collectors.NewGoCollector(
+			collectors.WithGoCollectorRuntimeMetrics(
+				collectors.GoRuntimeMetricsRule{Matcher: regexp.MustCompile("/sched/latencies:seconds")},
+			),
+		),
+	)
+}