metrics: Add http_requests metric

metrics.go

@@ -10,34 +10,45 @@ import (
 	"github.com/gorilla/mux"
 	"github.com/pkg/errors"
 	"github.com/prometheus/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/promauto"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	bolt "go.etcd.io/bbolt"
 )
 
-func StartMetricsServer(addr string, db *db.Database) {
-	var (
-		_ = promauto.NewGaugeFunc(prometheus.GaugeOpts{
-			Namespace: "rushlink",
-			Subsystem: "pastes",
-			Name:      "urls_total",
-			Help:      "The current amount of pastes in the database.",
-		}, func() float64 {
-			var metric float64
-			if err := db.Bolt.View(func(tx *bolt.Tx) error {
-				bucket := tx.Bucket([]byte("pastes"))
-				if bucket == nil {
-					return errors.New("bucket 'pastes' could not be found")
-				}
-				metric = float64(bucket.Stats().KeyN)
-				return nil
-			}); err != nil {
-				log.Printf("error: %v", errors.Wrap(err, "fetching pastes_total metric"))
-				return 0
-			}
-			return metric
-		})
-	)
+const metricNamespace = "rushlink"
+
+var metricRequestsTotalCounter = prometheus.NewCounterVec(prometheus.CounterOpts{
+	Namespace: metricNamespace,
+	Subsystem: "http",
+	Name:      "requests_total",
+	Help:      "How many HTTP requests processed, partitioned by status code and HTTP method.",
+}, []string{"code", "method"})
+
+func metricURLsTotal(database *db.Database) float64 {
+	var metric float64
+	if err := database.Bolt.View(func(tx *bolt.Tx) error {
+		bucket := tx.Bucket([]byte("pastes"))
+		if bucket == nil {
+			return errors.New("bucket 'pastes' could not be found")
+		}
+		metric = float64(bucket.Stats().KeyN)
+		return nil
+	}); err != nil {
+		log.Printf("error: %v", errors.Wrap(err, "fetching pastes_total metric"))
+		return 0
+	}
+	return metric
+}
+
+// StartMetricsServer starts sering Prometheus metrics exports on addr
+func StartMetricsServer(addr string, database *db.Database, fs *db.FileStore) {
+	prometheus.MustRegister(metricRequestsTotalCounter)
+
+	prometheus.MustRegister(prometheus.NewGaugeFunc(prometheus.GaugeOpts{
+		Namespace: metricNamespace,
+		Subsystem: "pastes",
+		Name:      "urls_total",
+		Help:      "The current amount of pastes in the database.",
+	}, func() float64 { return metricURLsTotal(database) }))
 
 	router := mux.NewRouter()
 	router.Handle("/metrics", promhttp.Handler()).Methods("GET")