Add soju_upstream_connect_errors_total metric

server.go

@@ -106,6 +106,8 @@ type Server struct {
 		upstreamInMessagesTotal    prometheus.Counter
 		downstreamOutMessagesTotal prometheus.Counter
 		downstreamInMessagesTotal  prometheus.Counter
+
+		upstreamConnectErrorsTotal prometheus.Counter
 	}
 }
 
@@ -195,6 +197,11 @@ func (s *Server) registerMetrics() {
 		Name: "soju_downstream_in_messages_total",
 		Help: "Total number of incoming messages received from downstream clients",
 	})
+
+	s.metrics.upstreamConnectErrorsTotal = factory.NewCounter(prometheus.CounterOpts{
+		Name: "soju_upstream_connect_errors_total",
+		Help: "Total number of upstream connection errors",
+	})
 }
 
 func (s *Server) Shutdown() {

user.go

@@ -209,6 +209,7 @@ func (net *network) run() {
 			net.logger.Printf("failed to connect to upstream server %q: %v", net.Addr, err)
 			net.user.events <- eventUpstreamConnectionError{net, fmt.Errorf("failed to connect: %v", err)}
 			net.user.srv.metrics.upstreams.Add(-1)
+			net.user.srv.metrics.upstreamConnectErrorsTotal.Inc()
 			continue
 		}
 
@@ -226,6 +227,7 @@ func (net *network) run() {
 			net.user.events <- eventUpstreamConnectionError{net, fmt.Errorf("failed to register: %v", text)}
 			uc.Close()
 			net.user.srv.metrics.upstreams.Add(-1)
+			net.user.srv.metrics.upstreamConnectErrorsTotal.Inc()
 			continue
 		}