Add redaction to request / response

Adding redaction option to request and response so consumer of the library can hide sensitive values

References: open-telemetry#3895

instrumentation/net/http/otelhttp/config.go

@@ -20,6 +20,7 @@ import (
 	"net/http/httptrace"
 
 	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/metric"
 	"go.opentelemetry.io/otel/propagation"
 	"go.opentelemetry.io/otel/trace"
@@ -32,18 +33,19 @@ const (
 // config represents the configuration options available for the http.Handler
 // and http.Transport types.
 type config struct {
-	ServerName        string
-	Tracer            trace.Tracer
-	Meter             metric.Meter
-	Propagators       propagation.TextMapPropagator
-	SpanStartOptions  []trace.SpanStartOption
-	PublicEndpoint    bool
-	PublicEndpointFn  func(*http.Request) bool
-	ReadEvent         bool
-	WriteEvent        bool
-	Filters           []Filter
-	SpanNameFormatter func(string, *http.Request) string
-	ClientTrace       func(context.Context) *httptrace.ClientTrace
+	ServerName         string
+	Tracer             trace.Tracer
+	Meter              metric.Meter
+	Propagators        propagation.TextMapPropagator
+	SpanStartOptions   []trace.SpanStartOption
+	PublicEndpoint     bool
+	PublicEndpointFn   func(*http.Request) bool
+	ReadEvent          bool
+	WriteEvent         bool
+	Filters            []Filter
+	SpanNameFormatter  func(string, *http.Request) string
+	ClientTrace        func(context.Context) *httptrace.ClientTrace
+	RedactedAttributes map[attribute.Key]struct{}
 
 	TracerProvider trace.TracerProvider
 	MeterProvider  metric.MeterProvider
@@ -63,8 +65,9 @@ func (o optionFunc) apply(c *config) {
 // newConfig creates a new config struct and applies opts to it.
 func newConfig(opts ...Option) *config {
 	c := &config{
-		Propagators:   otel.GetTextMapPropagator(),
-		MeterProvider: otel.GetMeterProvider(),
+		Propagators:        otel.GetTextMapPropagator(),
+		MeterProvider:      otel.GetMeterProvider(),
+		RedactedAttributes: map[attribute.Key]struct{}{},
 	}
 	for _, opt := range opts {
 		opt.apply(c)
@@ -153,6 +156,16 @@ func WithFilter(f Filter) Option {
 	})
 }
 
+// WithRedactedAttributes will be replaced by fixed '****' values for the request / response
+// names provided. By default, no request / response are redacted.
+func WithRedactedAttributes(attributes ...attribute.Key) Option {
+	return optionFunc(func(ct *config) {
+		for _, att := range attributes {
+			ct.RedactedAttributes[att] = struct{}{}
+		}
+	})
+}
+
 type event int
 
 // Different types of events that can be recorded, see WithMessageEvents.

instrumentation/net/http/otelhttp/handler.go

@@ -35,18 +35,19 @@ type middleware struct {
 	operation string
 	server    string
 
-	tracer            trace.Tracer
-	meter             metric.Meter
-	propagators       propagation.TextMapPropagator
-	spanStartOptions  []trace.SpanStartOption
-	readEvent         bool
-	writeEvent        bool
-	filters           []Filter
-	spanNameFormatter func(string, *http.Request) string
-	counters          map[string]metric.Int64Counter
-	valueRecorders    map[string]metric.Float64Histogram
-	publicEndpoint    bool
-	publicEndpointFn  func(*http.Request) bool
+	tracer             trace.Tracer
+	meter              metric.Meter
+	propagators        propagation.TextMapPropagator
+	spanStartOptions   []trace.SpanStartOption
+	readEvent          bool
+	writeEvent         bool
+	filters            []Filter
+	redactedAttributes map[attribute.Key]struct{}
+	spanNameFormatter  func(string, *http.Request) string
+	counters           map[string]metric.Int64Counter
+	valueRecorders     map[string]metric.Float64Histogram
+	publicEndpoint     bool
+	publicEndpointFn   func(*http.Request) bool
 }
 
 func defaultHandlerFormatter(operation string, _ *http.Request) string {
@@ -91,6 +92,7 @@ func (h *middleware) configure(c *config) {
 	h.readEvent = c.ReadEvent
 	h.writeEvent = c.WriteEvent
 	h.filters = c.Filters
+	h.redactedAttributes = c.RedactedAttributes
 	h.spanNameFormatter = c.SpanNameFormatter
 	h.publicEndpoint = c.PublicEndpoint
 	h.publicEndpointFn = c.PublicEndpointFn
@@ -135,7 +137,7 @@ func (h *middleware) serveHTTP(w http.ResponseWriter, r *http.Request, next http
 
 	ctx := h.propagators.Extract(r.Context(), propagation.HeaderCarrier(r.Header))
 	opts := []trace.SpanStartOption{
-		trace.WithAttributes(semconvutil.HTTPServerRequest(h.server, r)...),
+		trace.WithAttributes(h.redactAttributes(semconvutil.HTTPServerRequest(h.server, r))...),
 	}
 	if h.server != "" {
 		hostAttr := semconv.NetHostName(h.server)
@@ -223,7 +225,7 @@ func (h *middleware) serveHTTP(w http.ResponseWriter, r *http.Request, next http
 	if rww.statusCode > 0 {
 		attributes = append(attributes, semconv.HTTPStatusCode(rww.statusCode))
 	}
-	o := metric.WithAttributes(attributes...)
+	o := metric.WithAttributes(h.redactAttributes(attributes)...)
 	h.counters[RequestContentLength].Add(ctx, bw.read, o)
 	h.counters[ResponseContentLength].Add(ctx, rww.written, o)
 
@@ -267,3 +269,20 @@ func WithRouteTag(route string, h http.Handler) http.Handler {
 		h.ServeHTTP(w, r)
 	})
 }
+
+// redactAttributes - return []keyValue with applied redaction to attributes if match key in redactedAttributes.
+func (h *middleware) redactAttributes(attributes []attribute.KeyValue) []attribute.KeyValue {
+	var result []attribute.KeyValue
+	for _, att := range attributes {
+		result = append(result, h.redactAttribute(att))
+	}
+	return result
+}
+
+// redactAttribute - return keyValue with applied redaction to attributes if match key in redactedAttributes.
+func (h *middleware) redactAttribute(keyValue attribute.KeyValue) attribute.KeyValue {
+	if _, ok := h.redactedAttributes[keyValue.Key]; ok {
+		return attribute.KeyValue{Key: keyValue.Key, Value: attribute.StringValue("****")}
+	}
+	return keyValue
+}

instrumentation/net/http/otelhttp/test/config_test.go

@@ -20,6 +20,8 @@ import (
 	"net/http/httptest"
 	"testing"
 
+	"go.opentelemetry.io/otel/attribute"
+
 	"github.com/stretchr/testify/assert"
 
 	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
@@ -68,6 +70,47 @@ func TestBasicFilter(t *testing.T) {
 	}
 }
 
+func TestBasicAttributeRedacted(t *testing.T) {
+	rr := httptest.NewRecorder()
+
+	spanRecorder := tracetest.NewSpanRecorder()
+	provider := trace.NewTracerProvider(trace.WithSpanProcessor(spanRecorder))
+	redactedKey := attribute.Key("http.method")
+
+	h := otelhttp.NewHandler(
+		http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			if _, err := io.WriteString(w, "hello world"); err != nil {
+				t.Fatal(err)
+			}
+		}), "test_handler",
+		otelhttp.WithTracerProvider(provider),
+		otelhttp.WithRedactedAttributes(redactedKey),
+	)
+
+	r, err := http.NewRequest(http.MethodGet, "http://localhost/", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	h.ServeHTTP(rr, r)
+	if got, expected := rr.Result().StatusCode, http.StatusOK; got != expected {
+		t.Fatalf("got %d, expected %d", got, expected)
+	}
+	if got := rr.Header().Get("Traceparent"); got != "" {
+		t.Fatal("expected empty trace header")
+	}
+	spans := spanRecorder.Ended()
+	if assert.Len(t, spans, 1) {
+		found := false
+		for _, a := range spans[0].Attributes() {
+			if a.Key == redactedKey {
+				found = true
+				assert.Equal(t, attribute.StringValue("****"), a.Value)
+			}
+		}
+		assert.True(t, found, "redacted key not found")
+	}
+}
+
 func TestSpanNameFormatter(t *testing.T) {
 	var testCases = []struct {
 		name      string

instrumentation/net/http/otelhttp/transport.go

@@ -20,6 +20,8 @@ import (
 	"net/http"
 	"net/http/httptrace"
 
+	"go.opentelemetry.io/otel/attribute"
+
 	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp/internal/semconvutil"
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/codes"
@@ -32,12 +34,13 @@ import (
 type Transport struct {
 	rt http.RoundTripper
 
-	tracer            trace.Tracer
-	propagators       propagation.TextMapPropagator
-	spanStartOptions  []trace.SpanStartOption
-	filters           []Filter
-	spanNameFormatter func(string, *http.Request) string
-	clientTrace       func(context.Context) *httptrace.ClientTrace
+	tracer             trace.Tracer
+	propagators        propagation.TextMapPropagator
+	spanStartOptions   []trace.SpanStartOption
+	filters            []Filter
+	redactedAttributes map[attribute.Key]struct{}
+	spanNameFormatter  func(string, *http.Request) string
+	clientTrace        func(context.Context) *httptrace.ClientTrace
 }
 
 var _ http.RoundTripper = &Transport{}
@@ -74,6 +77,7 @@ func (t *Transport) applyConfig(c *config) {
 	t.filters = c.Filters
 	t.spanNameFormatter = c.SpanNameFormatter
 	t.clientTrace = c.ClientTrace
+	t.redactedAttributes = c.RedactedAttributes
 }
 
 func defaultTransportFormatter(_ string, r *http.Request) string {
@@ -110,7 +114,7 @@ func (t *Transport) RoundTrip(r *http.Request) (*http.Response, error) {
 	}
 
 	r = r.WithContext(ctx)
-	span.SetAttributes(semconvutil.HTTPClientRequest(r)...)
+	span.SetAttributes(t.redactAttributes(semconvutil.HTTPClientRequest(r))...)
 	t.propagators.Inject(ctx, propagation.HeaderCarrier(r.Header))
 
 	res, err := t.rt.RoundTrip(r)
@@ -121,7 +125,7 @@ func (t *Transport) RoundTrip(r *http.Request) (*http.Response, error) {
 		return res, err
 	}
 
-	span.SetAttributes(semconvutil.HTTPClientResponse(res)...)
+	span.SetAttributes(t.redactAttributes(semconvutil.HTTPClientResponse(res))...)
 	span.SetStatus(semconvutil.HTTPClientStatus(res.StatusCode))
 	res.Body = newWrappedBody(span, res.Body)
 
@@ -191,3 +195,20 @@ func (wb *wrappedBody) Close() error {
 	}
 	return nil
 }
+
+// redactAttributes - return []keyValue with applied redaction to attributes if match key in redactedAttributes.
+func (t *Transport) redactAttributes(attributes []attribute.KeyValue) []attribute.KeyValue {
+	var result []attribute.KeyValue
+	for _, att := range attributes {
+		result = append(result, t.redactAttribute(att))
+	}
+	return result
+}
+
+// redactAttribute - return keyValue with applied redaction to attributes if match key in redactedAttributes.
+func (t *Transport) redactAttribute(keyValue attribute.KeyValue) attribute.KeyValue {
+	if _, ok := t.redactedAttributes[keyValue.Key]; ok {
+		return attribute.KeyValue{Key: keyValue.Key, Value: attribute.StringValue("****")}
+	}
+	return keyValue
+}