new: feat: add metrics endpoint and prometheus monitoring

monitoring/prometheus.go

@@ -0,0 +1,47 @@
+package monitoring
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+type Metrics struct {
+	IndexerDuration *prometheus.HistogramVec
+	IndexerErrors   *prometheus.CounterVec
+	IndexerRequests *prometheus.CounterVec
+	CacheHits       *prometheus.CounterVec
+	CacheMisses     *prometheus.CounterVec
+}
+
+func NewMetrics() *Metrics {
+	return &Metrics{
+		IndexerDuration: prometheus.NewHistogramVec(prometheus.HistogramOpts{
+			Name:    "indexer_duration_seconds",
+			Help:    "Duration of indexer requests",
+			Buckets: []float64{0.1, 0.5, 1, 2, 5, 10, 20, 30},
+		}, []string{"indexer"}),
+		IndexerErrors: prometheus.NewCounterVec(prometheus.CounterOpts{
+			Name: "indexer_errors_total",
+			Help: "Number of indexer errors",
+		}, []string{"indexer"}),
+		IndexerRequests: prometheus.NewCounterVec(prometheus.CounterOpts{
+			Name: "indexer_requests_total",
+			Help: "Number of indexer requests",
+		}, []string{"indexer"}),
+		CacheHits: prometheus.NewCounterVec(prometheus.CounterOpts{
+			Name: "cache_hits_total",
+			Help: "Number of cache hits",
+		}, []string{"cache"}),
+		CacheMisses: prometheus.NewCounterVec(prometheus.CounterOpts{
+			Name: "cache_misses_total",
+			Help: "Number of cache misses",
+		}, []string{"cache"}),
+	}
+}
+
+func (m *Metrics) Register() {
+	prometheus.MustRegister(m.IndexerDuration)
+	prometheus.MustRegister(m.IndexerErrors)
+	prometheus.MustRegister(m.IndexerRequests)
+	prometheus.MustRegister(m.CacheHits)
+	prometheus.MustRegister(m.CacheMisses)
+}