feat: add Trace Context HTTP headers

examples/gateway/car/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"context"
 	"flag"
 	"io"
 	"log"
@@ -32,6 +33,12 @@ func main() {
 		log.Fatal(err)
 	}
 
+	ctx := context.Background()
+	tp := common.NewTracerProvider()
+	defer func() {
+		_ = tp.Shutdown(ctx)
+	}()
+
 	handler := common.NewHandler(gwAPI)
 
 	log.Printf("Listening on http://localhost:%d", *port)

examples/gateway/car/main_test.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"context"
 	"io"
 	"net/http"
 	"net/http/httptest"
@@ -17,7 +18,7 @@ const (
 	BaseCID = "bafybeidhua2wpy27vo3t7ms22ybc7m7iqkm2opiebpjmo24lvixcnvznnu"
 )
 
-func newTestServer() (*httptest.Server, io.Closer, error) {
+func newTestServer(t *testing.T) (*httptest.Server, io.Closer, error) {
 	blockService, _, f, err := newBlockServiceFromCAR("./test.car")
 	if err != nil {
 		return nil, nil, err
@@ -29,13 +30,19 @@ func newTestServer() (*httptest.Server, io.Closer, error) {
 		return nil, nil, err
 	}
 
+	ctx := context.Background()
+	tp := common.NewTracerProvider()
+	t.Cleanup(func() {
+		_ = tp.Shutdown(ctx)
+	})
+
 	handler := common.NewHandler(gateway)
 	ts := httptest.NewServer(handler)
 	return ts, f, nil
 }
 
 func TestDirectoryTraverse(t *testing.T) {
-	ts, f, err := newTestServer()
+	ts, f, err := newTestServer(t)
 	assert.Nil(t, err)
 	defer f.Close()
 
@@ -49,7 +56,7 @@ func TestDirectoryTraverse(t *testing.T) {
 }
 
 func TestFile(t *testing.T) {
-	ts, f, err := newTestServer()
+	ts, f, err := newTestServer(t)
 	assert.Nil(t, err)
 	defer f.Close()
 
@@ -63,7 +70,7 @@ func TestFile(t *testing.T) {
 }
 
 func TestDirectoryAsDAG(t *testing.T) {
-	ts, f, err := newTestServer()
+	ts, f, err := newTestServer(t)
 	assert.Nil(t, err)
 	defer f.Close()
 
@@ -107,3 +114,16 @@ func TestDirectoryAsDAG(t *testing.T) {
 	assert.Nil(t, err)
 	assert.EqualValues(t, hash.String(), "bafybeigmlfksb374fdkxih4urny2yiyazyra2375y2e4a72b3jcrnthnau")
 }
+
+func TestTraceContextPresent(t *testing.T) {
+	ts, f, err := newTestServer(t)
+	assert.Nil(t, err)
+	defer f.Close()
+
+	res, err := http.Get(ts.URL + "/ipfs/" + BaseCID)
+	assert.Nil(t, err)
+	defer res.Body.Close()
+
+	traceparent := res.Header.Get("Traceparent")
+	assert.NotEmpty(t, traceparent)
+}

examples/gateway/common/handler.go

@@ -6,6 +6,7 @@ import (
 	"github.com/ipfs/boxo/gateway"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
 )
 
 func NewHandler(gwAPI gateway.IPFSBackend) http.Handler {
@@ -58,10 +59,15 @@ func NewHandler(gwAPI gateway.IPFSBackend) http.Handler {
 	var handler http.Handler
 	handler = gateway.WithHostname(mux, gwAPI, publicGateways, noDNSLink)
 
-	// Finally, wrap with the withConnect middleware. This is required since we use
+	// Then, wrap with the withConnect middleware. This is required since we use
 	// http.ServeMux which does not support CONNECT by default.
 	handler = withConnect(handler)
 
+	// Finally, wrap with the otelhttp handler. This will allow the tracing system
+	// to work and for correct propagation of tracing headers. This step is optional
+	// and only required if you want to use tracing.
+	handler = otelhttp.NewHandler(handler, "Gateway.Request")
+
 	return handler
 }
 

examples/gateway/common/tracing.go

@@ -0,0 +1,16 @@
+package common
+
+import (
+	"go.opentelemetry.io/contrib/propagators/autoprop"
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/sdk/trace"
+)
+
+func NewTracerProvider() *trace.TracerProvider {
+	tp := trace.NewTracerProvider()
+
+	otel.SetTracerProvider(tp)
+	otel.SetTextMapPropagator(autoprop.NewTextMapPropagator())
+
+	return tp
+}

examples/gateway/proxy/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"context"
 	"flag"
 	"log"
 	"net/http"
@@ -37,6 +38,12 @@ func main() {
 		log.Fatal(err)
 	}
 
+	ctx := context.Background()
+	tp := common.NewTracerProvider()
+	defer func() {
+		_ = tp.Shutdown(ctx)
+	}()
+
 	handler := common.NewHandler(gwAPI)
 
 	log.Printf("Listening on http://localhost:%d", *port)

examples/go.mod

@@ -15,6 +15,10 @@ require (
 	github.com/multiformats/go-multicodec v0.8.1
 	github.com/prometheus/client_golang v1.14.0
 	github.com/stretchr/testify v1.8.2
+	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.40.0
+	go.opentelemetry.io/contrib/propagators/autoprop v0.40.0
+	go.opentelemetry.io/otel v1.14.0
+	go.opentelemetry.io/otel/sdk v1.14.0
 )
 
 require (
@@ -33,6 +37,7 @@ require (
 	github.com/docker/go-units v0.5.0 // indirect
 	github.com/dustin/go-humanize v1.0.0 // indirect
 	github.com/elastic/gosigar v0.14.2 // indirect
+	github.com/felixge/httpsnoop v1.0.3 // indirect
 	github.com/flynn/noise v1.0.0 // indirect
 	github.com/francoispqt/gojay v1.2.13 // indirect
 	github.com/gabriel-vasile/mimetype v1.4.1 // indirect
@@ -125,7 +130,11 @@ require (
 	github.com/whyrusleeping/chunker v0.0.0-20181014151217-fe64bd25879f // indirect
 	github.com/whyrusleeping/go-keyspace v0.0.0-20160322163242-5b898ac5add1 // indirect
 	go.opencensus.io v0.24.0 // indirect
-	go.opentelemetry.io/otel v1.14.0 // indirect
+	go.opentelemetry.io/contrib/propagators/aws v1.15.0 // indirect
+	go.opentelemetry.io/contrib/propagators/b3 v1.15.0 // indirect
+	go.opentelemetry.io/contrib/propagators/jaeger v1.15.0 // indirect
+	go.opentelemetry.io/contrib/propagators/ot v1.15.0 // indirect
+	go.opentelemetry.io/otel/metric v0.37.0 // indirect
 	go.opentelemetry.io/otel/trace v1.14.0 // indirect
 	go.uber.org/atomic v1.10.0 // indirect
 	go.uber.org/dig v1.15.0 // indirect

examples/go.sum

@@ -105,6 +105,8 @@ github.com/envoyproxy/go-control-plane v0.9.0/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymF
 github.com/envoyproxy/go-control-plane v0.9.1-0.20191026205805-5f8ba28d4473/go.mod h1:YTl/9mNaCwkRvm6d1a2C3ymFceY/DCBVvsKhRF0iEA4=
 github.com/envoyproxy/go-control-plane v0.9.4/go.mod h1:6rpuAdCZL397s3pYoYcLgu1mIlRU8Am5FuJP05cCM98=
 github.com/envoyproxy/protoc-gen-validate v0.1.0/go.mod h1:iSmxcyjqTsJpI2R4NaDN7+kN2VEUnK/pcBlmesArF7c=
+github.com/felixge/httpsnoop v1.0.3 h1:s/nj+GCswXYzN5v2DpNMuMQYe+0DDwt5WVCU6CWBdXk=
+github.com/felixge/httpsnoop v1.0.3/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
 github.com/flynn/go-shlex v0.0.0-20150515145356-3f9db97f8568/go.mod h1:xEzjJPgXI435gkrCt3MPfRiAkVrwSbHsst4LCFVfpJc=
 github.com/flynn/noise v1.0.0 h1:DlTHqmzmvcEiKj+4RYo/imoswx/4r6iBlCMfVtrMXpQ=
 github.com/flynn/noise v1.0.0/go.mod h1:xbMo+0i6+IGbYdJhF31t2eR1BIU0CYc12+BNAKwUTag=
@@ -644,8 +646,24 @@ go.opencensus.io v0.22.3/go.mod h1:yxeiOL68Rb0Xd1ddK5vPZ/oVn4vY4Ynel7k9FzqtOIw=
 go.opencensus.io v0.22.4/go.mod h1:yxeiOL68Rb0Xd1ddK5vPZ/oVn4vY4Ynel7k9FzqtOIw=
 go.opencensus.io v0.24.0 h1:y73uSU6J157QMP2kn2r30vwW1A2W2WFwSCGnAVxeaD0=
 go.opencensus.io v0.24.0/go.mod h1:vNK8G9p7aAivkbmorf4v+7Hgx+Zs0yY+0fOtgBfjQKo=
+go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.40.0 h1:lE9EJyw3/JhrjWH/hEy9FptnalDQgj7vpbgC2KCCCxE=
+go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.40.0/go.mod h1:pcQ3MM3SWvrA71U4GDqv9UFDJ3HQsW7y5ZO3tDTlUdI=
+go.opentelemetry.io/contrib/propagators/autoprop v0.40.0 h1:Lj33jj7eIrBfIShiK8NU91u2BglKnUS1UUxVemuQJtw=
+go.opentelemetry.io/contrib/propagators/autoprop v0.40.0/go.mod h1:6QO816FeZ+6zahs6hYqbUCCsnNBm7o+t4iwVySpzcdI=
+go.opentelemetry.io/contrib/propagators/aws v1.15.0 h1:FLe+bRTMAhEALItDQt1U2S/rdq8/rGGJTJpOpCDvMu0=
+go.opentelemetry.io/contrib/propagators/aws v1.15.0/go.mod h1:Z/nqdjqKjErrS3gYoEMZt8//dt8VZbqalD0V+7vh7lM=
+go.opentelemetry.io/contrib/propagators/b3 v1.15.0 h1:bMaonPyFcAvZ4EVzkUNkfnUHP5Zi63CIDlA3dRsEg8Q=
+go.opentelemetry.io/contrib/propagators/b3 v1.15.0/go.mod h1:VjU0g2v6HSQ+NwfifambSLAeBgevjIcqmceaKWEzl0c=
+go.opentelemetry.io/contrib/propagators/jaeger v1.15.0 h1:xdJjwy5t/8I+TZehMMQ+r2h50HREihH2oMUhimQ+jug=
+go.opentelemetry.io/contrib/propagators/jaeger v1.15.0/go.mod h1:tU0nwW4QTvKceNUP60/PQm0FI8zDSwey7gIFt3RR/yw=
+go.opentelemetry.io/contrib/propagators/ot v1.15.0 h1:iBNejawWy7wWZ5msuZDNcMjBy14Wc0v3gCAXukGHN/Q=
+go.opentelemetry.io/contrib/propagators/ot v1.15.0/go.mod h1:0P7QQ+MHt6SXR1ATaMpewSiWlp8NbKErNLKcaU4EEKI=
 go.opentelemetry.io/otel v1.14.0 h1:/79Huy8wbf5DnIPhemGB+zEPVwnN6fuQybr/SRXa6hM=
 go.opentelemetry.io/otel v1.14.0/go.mod h1:o4buv+dJzx8rohcUeRmWUZhqupFvzWis188WlggnNeU=
+go.opentelemetry.io/otel/metric v0.37.0 h1:pHDQuLQOZwYD+Km0eb657A25NaRzy0a+eLyKfDXedEs=
+go.opentelemetry.io/otel/metric v0.37.0/go.mod h1:DmdaHfGt54iV6UKxsV9slj2bBRJcKC1B1uvDLIioc1s=
+go.opentelemetry.io/otel/sdk v1.14.0 h1:PDCppFRDq8A1jL9v6KMI6dYesaq+DFcDZvjsoGvxGzY=
+go.opentelemetry.io/otel/sdk v1.14.0/go.mod h1:bwIC5TjrNG6QDCHNWvW4HLHtUQ4I+VQDsnjhvyZCALM=
 go.opentelemetry.io/otel/trace v1.14.0 h1:wp2Mmvj41tDsyAJXiWDWpfNsOiIyd38fy85pyKcFq/M=
 go.opentelemetry.io/otel/trace v1.14.0/go.mod h1:8avnQLK+CG77yNLUae4ea2JDQ6iT+gozhnZjy/rw9G8=
 go.uber.org/atomic v1.6.0/go.mod h1:sABNBOSYdrvTF6hTgEIbc7YasKWGhgEQZyfxyTvoXHQ=

gateway/handler.go

@@ -83,7 +83,10 @@ type handler struct {
 // NewHandler returns an http.Handler that can act as a gateway to IPFS content
 // offlineApi is a version of the API that should not make network requests for missing data
 func NewHandler(c Config, api IPFSBackend) http.Handler {
-	return newHandlerWithMetrics(c, api)
+	var h http.Handler
+	h = newHandlerWithMetrics(c, api)
+	h = withTraceContext(h)
+	return h
 }
 
 // StatusResponseWriter enables us to override HTTP Status Code passed to

gateway/metrics.go

@@ -2,8 +2,8 @@ package gateway
 
 import (
 	"context"
-	"fmt"
 	"io"
+	"net/http"
 	"time"
 
 	"github.com/ipfs/boxo/coreiface/path"
@@ -12,6 +12,7 @@ import (
 	prometheus "github.com/prometheus/client_golang/prometheus"
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/propagation"
 	"go.opentelemetry.io/otel/trace"
 )
 
@@ -294,7 +295,20 @@ func newHistogramMetric(name string, help string) *prometheus.HistogramVec {
 	return histogramMetric
 }
 
+var tracer = otel.Tracer("boxo/gateway")
+
 // spanTrace starts a new span using the standard IPFS tracing conventions.
-func spanTrace(ctx context.Context, spanName string, opts ...trace.SpanStartOption) (context.Context, trace.Span) {
-	return otel.Tracer("boxo").Start(ctx, fmt.Sprintf("%s.%s", " Gateway", spanName), opts...)
+func spanTrace(ctx context.Context, name string, opts ...trace.SpanStartOption) (context.Context, trace.Span) {
+	return tracer.Start(ctx, name, opts...)
+}
+
+// withTraceContext sets the Trace Context (https://github.com/w3c/trace-context)
+// headers on the request based on the context and the propagator.
+func withTraceContext(next http.Handler) http.Handler {
+	props := otel.GetTextMapPropagator()
+
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		props.Inject(r.Context(), propagation.HeaderCarrier(w.Header()))
+		next.ServeHTTP(w, r)
+	})
 }