Add crawler_duration gauge and server_queries counter

internal/server.go

@@ -212,6 +212,10 @@ func (s *Server) setupMetrics() {
 		"crawler", "scraped",
 		"Number of links scraped by the crawler",
 	)
+	metrics.NewGauge(
+		"crawler", "duration",
+		"Duration of crawler tasks",
+	)
 
 	// server info
 	metrics.NewGaugeVec(
@@ -225,6 +229,10 @@ func (s *Server) setupMetrics() {
 			"version":      spyda.Version,
 			"commit":       spyda.Commit,
 		}).Set(1)
+	metrics.NewCounter(
+		"server", "queries",
+		"Number of queries processed",
+	)
 
 	s.AddRoute("GET", "/metrics", metrics.Handler())
 }