feat(routing/http/server): expose prometheus metrics (#718)

* feat: add instrumentation to delegated routing endpoint

* feat: allow passing in custom registry

* docs: update changelog

* chore: go mod tidy

* fix: create new registry unless set

* chore: adjust histogram buckets

* refactor: rename histogram

---------

Co-authored-by: Daniel N <2color@users.noreply.github.com>
Co-authored-by: Marcin Rataj <lidel@lidel.org>

CHANGELOG.md

@@ -16,6 +16,8 @@ The following emojis are used to highlight certain changes:
 
 ### Added
 
+- `routing/http/server`: added Prometheus instrumentation to http delegated routing endpoints.
+
 ### Changed
 
 - No longer using `github.com/jbenet/goprocess` to avoid requiring in dependents.

examples/go.sum

@@ -97,9 +97,8 @@ github.com/gogo/protobuf v1.3.1/go.mod h1:SlYgWuQ5SjCEi6WLHjHCa1yvBfUnHcTbrrZtXP
 github.com/gogo/protobuf v1.3.2 h1:Ov1cvc58UF3b5XjBnZv7+opcTcQFZebYjWzi34vdm4Q=
 github.com/gogo/protobuf v1.3.2/go.mod h1:P1XiOD3dCwIKUDQYPy72D8LYyHL2YPYrpS2s69NZV8Q=
 github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b/go.mod h1:SBH7ygxi8pfUlaOkMMuAQtPIUF8ecWP5IEl/CR7VP2Q=
+github.com/golang/groupcache v0.0.0-20200121045136-8c9f03a8e57e h1:1r7pUrabqp18hOBcwBwiTsbnFeTZHV9eER/QT5JVZxY=
 github.com/golang/groupcache v0.0.0-20200121045136-8c9f03a8e57e/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
-github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da h1:oI5xCqsCo564l8iNU+DwB5epxmsaqB+rhGL0m5jtYqE=
-github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
 github.com/golang/lint v0.0.0-20180702182130-06c8688daad7/go.mod h1:tluoj9z5200jBnyusfRPU2LqT6J+DAorxEvtC7LHB+E=
 github.com/golang/mock v1.1.1/go.mod h1:oTYuIxOrZwtPieC+H1uAHpcLFnEyAGVDL/k47Jfbm0A=
 github.com/golang/mock v1.2.0/go.mod h1:oTYuIxOrZwtPieC+H1uAHpcLFnEyAGVDL/k47Jfbm0A=
@@ -467,6 +466,8 @@ github.com/shurcooL/sanitized_anchor_name v1.0.0/go.mod h1:1NzhyTcUVG4SuEtjjoZeV
 github.com/shurcooL/users v0.0.0-20180125191416-49c67e49c537/go.mod h1:QJTqeLYEDaXHZDBsXlPCDqdhQuJkuw4NOtaxYe3xii4=
 github.com/shurcooL/webdavfs v0.0.0-20170829043945-18c3829fa133/go.mod h1:hKmq5kWdCj2z2KEozexVbfEZIWiTjhE0+UjmZgPqehw=
 github.com/sirupsen/logrus v1.7.0/go.mod h1:yWOB1SBYBC5VeMP7gHvWumXLIWorT60ONWic61uBYv0=
+github.com/slok/go-http-metrics v0.12.0 h1:mAb7hrX4gB4ItU6NkFoKYdBslafg3o60/HbGBRsKaG8=
+github.com/slok/go-http-metrics v0.12.0/go.mod h1:Ee/mdT9BYvGrlGzlClkK05pP2hRHmVbRF9dtUVS8LNA=
 github.com/smartystreets/assertions v1.2.0 h1:42S6lae5dvLc7BrLu/0ugRtcFVjoJNMC/N3yZFZkDFs=
 github.com/smartystreets/assertions v1.2.0/go.mod h1:tcbTF8ujkAEcZ8TElKY+i30BzYlVhC/LOxJk7iOWnoo=
 github.com/smartystreets/goconvey v1.7.2 h1:9RBaZCeXEQ3UselpuwUQHltGVXvdwm6cv1hgR6gDIPg=

go.mod

@@ -57,6 +57,7 @@ require (
 	github.com/polydawn/refmt v0.89.0
 	github.com/prometheus/client_golang v1.20.5
 	github.com/samber/lo v1.47.0
+	github.com/slok/go-http-metrics v0.12.0
 	github.com/spaolacci/murmur3 v1.1.0
 	github.com/stretchr/testify v1.9.0
 	github.com/whyrusleeping/base32 v0.0.0-20170828182744-c30ac30633cc
@@ -96,7 +97,6 @@ require (
 	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/go-task/slim-sprig/v3 v3.0.0 // indirect
 	github.com/godbus/dbus/v5 v5.1.0 // indirect
-	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
 	github.com/google/gopacket v1.1.19 // indirect
 	github.com/google/pprof v0.0.0-20241017200806-017d972448fc // indirect
 	github.com/gopherjs/gopherjs v0.0.0-20190430165422-3e4dfb77656c // indirect

go.sum

@@ -467,6 +467,8 @@ github.com/shurcooL/sanitized_anchor_name v1.0.0/go.mod h1:1NzhyTcUVG4SuEtjjoZeV
 github.com/shurcooL/users v0.0.0-20180125191416-49c67e49c537/go.mod h1:QJTqeLYEDaXHZDBsXlPCDqdhQuJkuw4NOtaxYe3xii4=
 github.com/shurcooL/webdavfs v0.0.0-20170829043945-18c3829fa133/go.mod h1:hKmq5kWdCj2z2KEozexVbfEZIWiTjhE0+UjmZgPqehw=
 github.com/sirupsen/logrus v1.7.0/go.mod h1:yWOB1SBYBC5VeMP7gHvWumXLIWorT60ONWic61uBYv0=
+github.com/slok/go-http-metrics v0.12.0 h1:mAb7hrX4gB4ItU6NkFoKYdBslafg3o60/HbGBRsKaG8=
+github.com/slok/go-http-metrics v0.12.0/go.mod h1:Ee/mdT9BYvGrlGzlClkK05pP2hRHmVbRF9dtUVS8LNA=
 github.com/smartystreets/assertions v1.2.0 h1:42S6lae5dvLc7BrLu/0ugRtcFVjoJNMC/N3yZFZkDFs=
 github.com/smartystreets/assertions v1.2.0/go.mod h1:tcbTF8ujkAEcZ8TElKY+i30BzYlVhC/LOxJk7iOWnoo=
 github.com/smartystreets/goconvey v1.7.2 h1:9RBaZCeXEQ3UselpuwUQHltGVXvdwm6cv1hgR6gDIPg=

routing/http/server/server.go

@@ -25,8 +25,12 @@ import (
 	"github.com/libp2p/go-libp2p/core/routing"
 	"github.com/multiformats/go-multiaddr"
 	"github.com/multiformats/go-multibase"
+	"github.com/prometheus/client_golang/prometheus"
 
 	logging "github.com/ipfs/go-log/v2"
+	metrics "github.com/slok/go-http-metrics/metrics/prometheus"
+	"github.com/slok/go-http-metrics/middleware"
+	middlewarestd "github.com/slok/go-http-metrics/middleware/std"
 )
 
 const (
@@ -122,6 +126,12 @@ func WithStreamingRecordsLimit(limit int) Option {
 	}
 }
 
+func WithPrometheusRegistry(reg prometheus.Registerer) Option {
+	return func(s *server) {
+		s.promRegistry = reg
+	}
+}
+
 func Handler(svc ContentRouter, opts ...Option) http.Handler {
 	server := &server{
 		svc:                   svc,
@@ -133,12 +143,28 @@ func Handler(svc ContentRouter, opts ...Option) http.Handler {
 		opt(server)
 	}
 
+	if server.promRegistry == nil {
+		server.promRegistry = prometheus.NewRegistry()
+	}
+
+	// Create middleware with prometheus recorder
+	mdlw := middleware.New(middleware.Config{
+		Recorder: metrics.NewRecorder(metrics.Config{
+			Registry: server.promRegistry,
+			Prefix:   "delegated_routing_server",
+
+			DurationBuckets: []float64{0.1, 0.5, 1, 2, 5, 8, 10, 20, 30},
+		}),
+	})
+
 	r := mux.NewRouter()
-	r.HandleFunc(findProvidersPath, server.findProviders).Methods(http.MethodGet)
-	r.HandleFunc(providePath, server.provide).Methods(http.MethodPut)
-	r.HandleFunc(findPeersPath, server.findPeers).Methods(http.MethodGet)
-	r.HandleFunc(GetIPNSPath, server.GetIPNS).Methods(http.MethodGet)
-	r.HandleFunc(GetIPNSPath, server.PutIPNS).Methods(http.MethodPut)
+	// Wrap each handler with the metrics middleware
+	r.Handle(findProvidersPath, middlewarestd.Handler(findProvidersPath, mdlw, http.HandlerFunc(server.findProviders))).Methods(http.MethodGet)
+	r.Handle(providePath, middlewarestd.Handler(providePath, mdlw, http.HandlerFunc(server.provide))).Methods(http.MethodPut)
+	r.Handle(findPeersPath, middlewarestd.Handler(findPeersPath, mdlw, http.HandlerFunc(server.findPeers))).Methods(http.MethodGet)
+	r.Handle(GetIPNSPath, middlewarestd.Handler(GetIPNSPath, mdlw, http.HandlerFunc(server.GetIPNS))).Methods(http.MethodGet)
+	r.Handle(GetIPNSPath, middlewarestd.Handler(GetIPNSPath, mdlw, http.HandlerFunc(server.PutIPNS))).Methods(http.MethodPut)
+
 	return r
 }
 
@@ -147,6 +173,7 @@ type server struct {
 	disableNDJSON         bool
 	recordsLimit          int
 	streamingRecordsLimit int
+	promRegistry          prometheus.Registerer
 }
 
 func (s *server) detectResponseType(r *http.Request) (string, error) {