feat: support OpenTelemetry tracing

go.mod

@@ -2,4 +2,9 @@ module github.com/aereal/go-openapi3-validation-middleware
 
 go 1.16
 
-require github.com/getkin/kin-openapi v0.122.0
+require (
+	github.com/getkin/kin-openapi v0.122.0
+	go.opentelemetry.io/otel v1.21.0
+	go.opentelemetry.io/otel/sdk v1.21.0
+	go.opentelemetry.io/otel/trace v1.21.0
+)

go.sum

@@ -4,13 +4,20 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/getkin/kin-openapi v0.122.0 h1:WB9Jbl0Hp/T79/JF9xlSW5Kl9uYdk/AWD0yAd9HOM10=
 github.com/getkin/kin-openapi v0.122.0/go.mod h1:PCWw/lfBrJY4HcdqE3jj+QFkaFK8ABoqo7PvqVhXXqw=
+github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
+github.com/go-logr/logr v1.3.0 h1:2y3SDp0ZXuc6/cjLSZ+Q3ir+QB9T/iG5yYRXqsagWSY=
+github.com/go-logr/logr v1.3.0/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
+github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
+github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
 github.com/go-openapi/jsonpointer v0.19.6 h1:eCs3fxoIi3Wh6vtgmLTOjdhSpiqphQ+DaPn38N2ZdrE=
 github.com/go-openapi/jsonpointer v0.19.6/go.mod h1:osyAmYz/mB/C3I+WsTTSgw1ONzaLJoLCyoi6/zppojs=
 github.com/go-openapi/swag v0.22.3/go.mod h1:UzaqsxGiab7freDnrUUra0MwWfN/q7tE4j+VcZ0yl14=
 github.com/go-openapi/swag v0.22.4 h1:QLMzNJnMGPRNDCbySlcj1x01tzU8/9LTTL9hZZZogBU=
 github.com/go-openapi/swag v0.22.4/go.mod h1:UzaqsxGiab7freDnrUUra0MwWfN/q7tE4j+VcZ0yl14=
 github.com/go-test/deep v1.0.8 h1:TDsG77qcSprGbC6vTN8OuXp5g+J+b5Pcguhf7Zt61VM=
 github.com/go-test/deep v1.0.8/go.mod h1:5C2ZWiW0ErCdrYzpqxLbTX7MG14M9iiw8DgHncVwcsE=
+github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/gorilla/mux v1.8.0 h1:i40aqfkR1h2SlN9hojwV5ZA91wcXFOvkdNIeFDP5koI=
 github.com/gorilla/mux v1.8.0/go.mod h1:DVbg23sWSpFRCP0SfiEN6jmj59UnW/n46BH5rLB71So=
 github.com/invopop/yaml v0.2.0 h1:7zky/qH+O0DwAyoobXUqvVBwgBFRxKoQ/3FjcVpjTMY=
@@ -37,12 +44,23 @@ github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpE
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
 github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
-github.com/stretchr/testify v1.8.2 h1:+h33VjcLVPDHtOdpUCuF+7gSuG3yGIftsP1YvFihtJ8=
 github.com/stretchr/testify v1.8.2/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
+github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
 github.com/ugorji/go v1.2.7 h1:qYhyWUUd6WbiM+C6JZAUkIJt/1WrjzNHY9+KCIjVqTo=
 github.com/ugorji/go v1.2.7/go.mod h1:nF9osbDWLy6bDVv/Rtoh6QgnvNDpmCalQV5urGCCS6M=
 github.com/ugorji/go/codec v1.2.7 h1:YPXUKf7fYbp/y8xloBqZOw2qaVggbfwMlI8WM3wZUJ0=
 github.com/ugorji/go/codec v1.2.7/go.mod h1:WGN1fab3R1fzQlVQTkfxVtIBhWDRqOviHU95kRgeqEY=
+go.opentelemetry.io/otel v1.21.0 h1:hzLeKBZEL7Okw2mGzZ0cc4k/A7Fta0uoPgaJCr8fsFc=
+go.opentelemetry.io/otel v1.21.0/go.mod h1:QZzNPQPm1zLX4gZK4cMi+71eaorMSGT3A4znnUvNNEo=
+go.opentelemetry.io/otel/metric v1.21.0 h1:tlYWfeo+Bocx5kLEloTjbcDwBuELRrIFxwdQ36PlJu4=
+go.opentelemetry.io/otel/metric v1.21.0/go.mod h1:o1p3CA8nNHW8j5yuQLdc1eeqEaPfzug24uvsyIEJRWM=
+go.opentelemetry.io/otel/sdk v1.21.0 h1:FTt8qirL1EysG6sTQRZ5TokkU8d0ugCj8htOgThZXQ8=
+go.opentelemetry.io/otel/sdk v1.21.0/go.mod h1:Nna6Yv7PWTdgJHVRD9hIYywQBRx7pbox6nwBnZIxl/E=
+go.opentelemetry.io/otel/trace v1.21.0 h1:WD9i5gzvoUPuXIXH24ZNBudiarZDKuekPqi/E8fpfLc=
+go.opentelemetry.io/otel/trace v1.21.0/go.mod h1:LGbsEB0f9LGjN+OZaQQ26sohbOmiMR+BaslueVtS/qQ=
+golang.org/x/sys v0.14.0 h1:Vz7Qs629MkJkGyHxUlRHizWJRG2j8fbQKjELVSNhy7Q=
+golang.org/x/sys v0.14.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=

middleware.go

@@ -1,6 +1,7 @@
 package openapi3middleware
 
 import (
+	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -9,6 +10,8 @@ import (
 	"github.com/getkin/kin-openapi/openapi3"
 	"github.com/getkin/kin-openapi/openapi3filter"
 	"github.com/getkin/kin-openapi/routers"
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/trace"
 )
 
 type middleware = func(next http.Handler) http.Handler
@@ -19,6 +22,7 @@ type MiddlewareOptions struct {
 	ReportFindRouteError          func(w http.ResponseWriter, r *http.Request, err error)
 	ReportRequestValidationError  func(w http.ResponseWriter, r *http.Request, err error)
 	ReportResponseValidationError func(w http.ResponseWriter, r *http.Request, err error)
+	TracerProvider                trace.TracerProvider
 }
 
 func (o MiddlewareOptions) reportFindRouteError(w http.ResponseWriter, r *http.Request, err error) {
@@ -60,13 +64,18 @@ func WithResponseValidation(options MiddlewareOptions) middleware {
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			ctx := r.Context()
+			ctx, span := getTracer(ctx, options).Start(ctx, "ResponseValidation")
+			defer span.End()
 			irw := newBufferingResponseWriter(w)
-			next.ServeHTTP(irw, r)
+			next.ServeHTTP(irw, r.WithContext(ctx))
 			ri, err := buildRequestValidationInputFromRequest(options.Router, r, options.ValidationOptions)
 			if frErr := new(findRouteErr); errors.As(err, &frErr) {
-				options.reportFindRouteError(w, r, frErr.Unwrap())
+				actualErr := frErr.Unwrap()
+				span.RecordError(actualErr)
+				options.reportFindRouteError(w, r, actualErr)
 				return
 			} else if err != nil {
+				span.RecordError(err)
 				respondErrorJSON(w, http.StatusInternalServerError, err)
 				return
 			}
@@ -81,6 +90,7 @@ func WithResponseValidation(options MiddlewareOptions) middleware {
 			bodyBytes := irw.buf.Bytes()
 			input.SetBodyBytes(bodyBytes)
 			if err := openapi3filter.ValidateResponse(ctx, input); err != nil {
+				span.RecordError(err)
 				options.reportRespError(w, r, err)
 				return
 			}
@@ -94,20 +104,26 @@ func WithResponseValidation(options MiddlewareOptions) middleware {
 func WithRequestValidation(options MiddlewareOptions) middleware {
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			ctx := r.Context()
+			ctx, span := getTracer(ctx, options).Start(ctx, "RequestValidation")
+			defer span.End()
 			input, err := buildRequestValidationInputFromRequest(options.Router, r, options.ValidationOptions)
 			if frErr := new(findRouteErr); errors.As(err, &frErr) {
-				options.reportFindRouteError(w, r, frErr.Unwrap())
+				actualErr := frErr.Unwrap()
+				span.RecordError(actualErr)
+				options.reportFindRouteError(w, r, actualErr)
 				return
 			} else if err != nil {
+				span.RecordError(err)
 				respondErrorJSON(w, http.StatusInternalServerError, err)
 				return
 			}
-			ctx := r.Context()
 			if err := openapi3filter.ValidateRequest(ctx, input); err != nil {
+				span.RecordError(err)
 				options.reportReqError(w, r, err)
 				return
 			}
-			next.ServeHTTP(w, r)
+			next.ServeHTTP(w, r.WithContext(ctx))
 		})
 	}
 }
@@ -218,3 +234,17 @@ func respondJSON(w http.ResponseWriter, statusCode int, payload interface{}) err
 	w.WriteHeader(statusCode)
 	return json.NewEncoder(w).Encode(payload)
 }
+
+const tracerName = "github.com/aereal/go-openapi3-validation-middleware"
+
+func getTracer(ctx context.Context, opts MiddlewareOptions) trace.Tracer {
+	tp := opts.TracerProvider
+	if tp == nil {
+		if span := trace.SpanFromContext(ctx); span.SpanContext().IsValid() {
+			tp = span.TracerProvider()
+		} else {
+			tp = otel.GetTracerProvider()
+		}
+	}
+	return tp.Tracer(tracerName)
+}

middleware_test.go

@@ -3,6 +3,7 @@ package openapi3middleware
 import (
 	"bufio"
 	"bytes"
+	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -20,6 +21,11 @@ import (
 	"github.com/getkin/kin-openapi/openapi3filter"
 	"github.com/getkin/kin-openapi/routers"
 	"github.com/getkin/kin-openapi/routers/gorillamux"
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/propagation"
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+	"go.opentelemetry.io/otel/sdk/trace/tracetest"
+	"go.opentelemetry.io/otel/trace"
 )
 
 var router routers.Router
@@ -182,6 +188,82 @@ func TestWithValidation(t *testing.T) {
 	}
 }
 
+func TestWithValidation_otel(t *testing.T) {
+	testCases := []struct {
+		name         string
+		buildOptions func(tp trace.TracerProvider) MiddlewareOptions
+		wantSpans    int
+	}{
+		{
+			name: "ok/explicitly passing TracerProvider",
+			buildOptions: func(tp trace.TracerProvider) MiddlewareOptions {
+				return MiddlewareOptions{
+					Router:         router,
+					TracerProvider: tp,
+				}
+			},
+			wantSpans: 3,
+		},
+		{
+			name: "ok/use TracerProvider comes from the current span",
+			buildOptions: func(_ trace.TracerProvider) MiddlewareOptions {
+				return MiddlewareOptions{Router: router}
+			},
+			wantSpans: 3,
+		},
+	}
+	for _, tc := range testCases {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			ctx, cancel := context.WithCancel(context.Background())
+			if deadline, ok := t.Deadline(); ok {
+				ctx, cancel = context.WithDeadline(ctx, deadline)
+			}
+			defer cancel()
+
+			exporter := tracetest.NewInMemoryExporter()
+			tp := sdktrace.NewTracerProvider(sdktrace.WithBatcher(exporter))
+
+			withOtel := func(next http.Handler) http.Handler {
+				return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+					ctx := otel.GetTextMapPropagator().Extract(r.Context(), propagation.HeaderCarrier(r.Header))
+					ctx, span := tp.Tracer("test").Start(ctx, fmt.Sprintf("%s %s", r.Method, r.URL.Path))
+					defer span.End()
+					next.ServeHTTP(w, r.WithContext(ctx))
+				})
+			}
+			handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				w.Header().Set("content-type", "application/json")
+				_ = json.NewEncoder(w).Encode(user{Name: "aereal", Age: 17, ID: "123"})
+			})
+			srv := httptest.NewServer(withOtel(WithValidation(tc.buildOptions(tp))(handler)))
+			defer srv.Close()
+
+			req := mustRequest(newRequest(http.MethodPost, srv.URL+"/users", map[string]string{"content-type": "application/json"}, `{"name":"aereal","age":17}`))
+			resp, err := srv.Client().Do(req.WithContext(ctx))
+			if err != nil {
+				t.Fatalf("http.Client.Do: %v", err)
+			}
+			defer resp.Body.Close()
+			if resp.StatusCode != http.StatusOK {
+				t.Errorf("unexpected status code: %d", resp.StatusCode)
+			}
+
+			if err := tp.ForceFlush(ctx); err != nil {
+				t.Fatal(err)
+			}
+			spans := exporter.GetSpans()
+			t.Logf("%d spans got", len(spans))
+			for i, span := range spans {
+				t.Logf("#%d: %#v", i, span)
+			}
+			if len(spans) != tc.wantSpans {
+				t.Errorf("spans count:\nwant: %d\ngot: %d", tc.wantSpans, len(spans))
+			}
+		})
+	}
+}
+
 func resumeResponse(testName string, got *http.Response) (*http.Response, error) {
 	imported, err := importResponse(testName)
 	if err == nil {