expose some Prometheus metrics

Author: marten-seemann

go.mod

@@ -6,10 +6,16 @@ require (
 	github.com/libp2p/go-libp2p-mplex v0.2.3
 	github.com/libp2p/go-libp2p-testing v0.1.1
 	github.com/libp2p/go-libp2p-transport-upgrader v0.2.0
+	github.com/libp2p/go-netroute v0.1.5 // indirect
 	github.com/libp2p/go-reuseport v0.0.2
 	github.com/libp2p/go-reuseport-transport v0.0.4
+	github.com/mikioh/tcp v0.0.0-20190314235350-803a9b46060c
+	github.com/mikioh/tcpinfo v0.0.0-20190314235526-30a79bb1804b
+	github.com/mikioh/tcpopt v0.0.0-20190314235656-172688c1accc // indirect
 	github.com/multiformats/go-multiaddr v0.3.1
 	github.com/multiformats/go-multiaddr-fmt v0.1.0
+	github.com/multiformats/go-multihash v0.0.15 // indirect
+	github.com/prometheus/client_golang v1.10.0
 )
 
 go 1.12