Add tracing

server/middleware.go

@@ -1,10 +1,12 @@
 package server
 
 import (
+	"fmt"
 	"net/http"
 	"time"
 
 	"github.com/go-chi/chi/v5/middleware"
+	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
 )
 
 func (s *Server) MiddlewareLogging(next http.Handler) http.Handler {
@@ -33,3 +35,12 @@ func (s *Server) MiddlewareLogging(next http.Handler) http.Handler {
 	}
 	return http.HandlerFunc(fn)
 }
+
+func (s *Server) MiddlewareTracing(next http.Handler) http.Handler {
+	fn := func(w http.ResponseWriter, r *http.Request) {
+		h := otelhttp.NewHandler(next, fmt.Sprintf("%s %s", r.Method, r.URL.Path))
+
+		h.ServeHTTP(w, r)
+	}
+	return http.HandlerFunc(fn)
+}

server/server.go

@@ -1,12 +1,14 @@
 package server
 
 import (
+	"context"
 	"encoding/json"
 	"io"
 	"log/slog"
 	"net/http"
 	"net/url"
 	"strings"
+	"time"
 
 	"git.t-juice.club/microfilm/auth"
 	"git.t-juice.club/microfilm/auth/authmw"
@@ -14,6 +16,14 @@ import (
 	"github.com/go-chi/chi/v5"
 	"github.com/go-chi/chi/v5/middleware"
 	"github.com/nats-io/nats.go"
+	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
+	"go.opentelemetry.io/otel/propagation"
+	"go.opentelemetry.io/otel/sdk/resource"
+	tracesdk "go.opentelemetry.io/otel/sdk/trace"
+	semconv "go.opentelemetry.io/otel/semconv/v1.21.0"
+	"go.opentelemetry.io/otel/trace"
 )
 
 type Service string
@@ -40,6 +50,7 @@ func NewServer(config *Config) (*Server, error) {
 	r := chi.NewRouter()
 	r.Use(middleware.RealIP)
 	r.Use(middleware.RequestID)
+	r.Use(srv.MiddlewareTracing)
 	r.Use(srv.MiddlewareLogging)
 
 	r.Get("/info", InfoHandler)
@@ -51,9 +62,35 @@ func NewServer(config *Config) (*Server, error) {
 	srv.Handler = r
 	srv.Addr = config.ListenAddr
 
+	tp, err := tracerProvider("jaeger:4318")
+	if err != nil {
+		return nil, err
+	}
+	otel.SetTracerProvider(tp)
+
 	return srv, nil
 }
 
+func tracerProvider(url string) (*tracesdk.TracerProvider, error) {
+	exp, err := otlptracehttp.New(context.Background(), otlptracehttp.WithEndpoint(url), otlptracehttp.WithInsecure())
+	if err != nil {
+		return nil, err
+	}
+
+	res := resource.NewWithAttributes(semconv.SchemaURL,
+		semconv.ServiceName("mf-proxy"),
+		semconv.ServiceVersion(proxy.Version),
+	)
+	tp := tracesdk.NewTracerProvider(
+		tracesdk.WithBatcher(exp, tracesdk.WithBatchTimeout(time.Second)),
+		tracesdk.WithResource(res),
+	)
+	otel.SetTracerProvider(tp)
+	otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(propagation.TraceContext{}, propagation.Baggage{}))
+
+	return tp, nil
+}
+
 func InfoHandler(w http.ResponseWriter, r *http.Request) {
 	enc := json.NewEncoder(w)
 
@@ -73,11 +110,18 @@ func WriteError(w http.ResponseWriter, response proxy.ErrorResponse) {
 
 func (s *Server) ProxyHandler(service Service) http.Handler {
 	fn := func(w http.ResponseWriter, r *http.Request) {
-		client := http.Client{}
+		ctx := r.Context()
+		client := http.Client{
+			Transport: otelhttp.NewTransport(http.DefaultTransport),
+		}
 		defer r.Body.Close()
 
 		newURL := s.convertURL(r.URL, service)
-		req, err := http.NewRequest(r.Method, newURL.String(), r.Body)
+
+		span := trace.SpanFromContext(ctx)
+
+		span.AddEvent("Do proxy forward")
+		req, err := http.NewRequestWithContext(ctx, r.Method, newURL.String(), r.Body)
 		if err != nil {
 			s.Logger.Warn("Failed to create forwarding request.", "error", err, "url", newURL)
 			WriteError(w, proxy.ErrorResponse{