feat: prometheus metrics

internal/metrics/metrics.go

@@ -0,0 +1,50 @@
+package metrics
+
+import (
+	"github.com/gorilla/mux"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+var (
+	pasteLengthHistogram = promauto.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Namespace: "goblin",
+			Subsystem: "paste",
+			Name:      "length",
+			Help:      "Length of pastes",
+			Buckets:   prometheus.ExponentialBuckets(1, 2, 10), // Example buckets
+		},
+		[]string{"status"}, // Labels for success/failure
+	)
+
+	pasteCreatedCounter = promauto.NewCounterVec(
+		prometheus.CounterOpts{
+			Namespace: "goblin",
+			Subsystem: "paste",
+			Name:      "created_total",
+			Help:      "Total number of pastes created",
+		},
+		[]string{"status"}, // Labels for success/failure
+	)
+)
+
+// ObservePasteLength records the length of pastes.
+func ObservePasteLength(status string, length float64) {
+	pasteLengthHistogram.WithLabelValues(status).Observe(length)
+}
+
+// IncrementPasteCreatedCounter increments the paste creation counter.
+func IncrementPasteCreatedCounter(status string) {
+	pasteCreatedCounter.WithLabelValues(status).Inc()
+}
+
+// InitPrometheus initializes Prometheus metrics and registers a handler for /metrics endpoint.
+func InitPrometheus(router *mux.Router) {
+	// Register Prometheus metrics collectors here
+	// For example, you can use promauto to define and register metrics
+
+	// Register Prometheus HTTP handler for /metrics endpoint with the Mux router
+	router.Handle("/metrics", promhttp.Handler())
+}