contrib/google.golang.org/grpc: Fallback to dynamic service names if …

…no global is found (#2051)

Co-authored-by: Peter Kalmakis <peter.kalmakis@gmail.com>
Co-authored-by: Katie Hockman <katie@hockman.dev>
Co-authored-by: Diana Shevchenko <40775148+dianashevchenko@users.noreply.github.com>

contrib/google.golang.org/grpc/grpc.go

@@ -53,11 +53,11 @@ func (cfg *config) startSpanOptions(opts ...tracer.StartSpanOption) []tracer.Sta
 }
 
 func startSpanFromContext(
-	ctx context.Context, method, operation, service string, opts ...tracer.StartSpanOption,
+	ctx context.Context, method, operation string, serviceFn func() string, opts ...tracer.StartSpanOption,
 ) (ddtrace.Span, context.Context) {
 	methodElements := strings.SplitN(strings.TrimPrefix(method, "/"), "/", 2)
 	opts = append(opts,
-		tracer.ServiceName(service),
+		tracer.ServiceName(serviceFn()),
 		tracer.ResourceName(method),
 		tracer.Tag(tagMethodName, method),
 		spanTypeRPC,

contrib/google.golang.org/grpc/grpc_test.go

@@ -6,8 +6,12 @@
 package grpc
 
 import (
+	"bytes"
+	"encoding/json"
 	"fmt"
+	"io"
 	"net"
+	"net/http"
 	"strings"
 	"sync/atomic"
 	"testing"
@@ -23,9 +27,11 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"github.com/tinylib/msgp/msgp"
 	context "golang.org/x/net/context"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/credentials/insecure"
 	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/status"
 )
@@ -1203,3 +1209,83 @@ func BenchmarkUnaryServerInterceptor(b *testing.B) {
 		}
 	})
 }
+
+type roundTripper struct {
+	assertSpanFromRequest func(r *http.Request)
+}
+
+func (rt *roundTripper) RoundTrip(r *http.Request) (*http.Response, error) {
+	rt.assertSpanFromRequest(r)
+	return http.DefaultTransport.RoundTrip(r)
+}
+
+func TestIssue2050(t *testing.T) {
+	// https://github.com/DataDog/dd-trace-go/issues/2050
+	t.Setenv("DD_SERVICE", "some-dd-service")
+
+	spansFound := make(chan bool, 1)
+
+	httpClient := &http.Client{
+		Transport: &roundTripper{
+			assertSpanFromRequest: func(r *http.Request) {
+				if r.URL.Path != "/v0.4/traces" {
+					return
+				}
+				req := r.Clone(context.Background())
+				defer req.Body.Close()
+
+				buf, err := io.ReadAll(req.Body)
+				require.NoError(t, err)
+
+				var payload bytes.Buffer
+				_, err = msgp.UnmarshalAsJSON(&payload, buf)
+				require.NoError(t, err)
+
+				var trace [][]map[string]interface{}
+				err = json.Unmarshal(payload.Bytes(), &trace)
+				require.NoError(t, err)
+
+				if len(trace) == 0 {
+					return
+				}
+				require.Len(t, trace, 2)
+				s0 := trace[0][0]
+				s1 := trace[1][0]
+
+				assert.Equal(t, "server", s0["meta"].(map[string]interface{})["span.kind"])
+				assert.Equal(t, "some-dd-service", s0["service"])
+
+				assert.Equal(t, "client", s1["meta"].(map[string]interface{})["span.kind"])
+				assert.Equal(t, "grpc.client", s1["service"])
+				close(spansFound)
+			},
+		},
+	}
+	serverInterceptors := []grpc.ServerOption{
+		grpc.UnaryInterceptor(UnaryServerInterceptor()),
+		grpc.StreamInterceptor(StreamServerInterceptor()),
+	}
+	clientInterceptors := []grpc.DialOption{
+		grpc.WithTransportCredentials(insecure.NewCredentials()),
+		grpc.WithUnaryInterceptor(UnaryClientInterceptor()),
+		grpc.WithStreamInterceptor(StreamClientInterceptor()),
+	}
+	rig, err := newRigWithInterceptors(serverInterceptors, clientInterceptors)
+	require.NoError(t, err)
+	defer rig.Close()
+
+	// call tracer.Start after integration is initialized, to reproduce the issue
+	tracer.Start(tracer.WithHTTPClient(httpClient))
+	defer tracer.Stop()
+
+	_, err = rig.client.Ping(context.Background(), &FixtureRequest{Name: "pass"})
+	require.NoError(t, err)
+
+	select {
+	case <-spansFound:
+		return
+
+	case <-time.After(5 * time.Second):
+		assert.Fail(t, "spans not found")
+	}
+}

contrib/google.golang.org/grpc/option.go

@@ -9,6 +9,8 @@ import (
 	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace"
 	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer"
 	"gopkg.in/DataDog/dd-trace-go.v1/internal"
+	"gopkg.in/DataDog/dd-trace-go.v1/internal/globalconfig"
+	"gopkg.in/DataDog/dd-trace-go.v1/internal/log"
 	"gopkg.in/DataDog/dd-trace-go.v1/internal/namingschema"
 
 	"google.golang.org/grpc/codes"
@@ -24,7 +26,7 @@ const (
 type Option func(*config)
 
 type config struct {
-	serviceName         string
+	serviceName         func() string
 	spanName            string
 	nonErrorCodes       map[codes.Code]bool
 	traceStreamCalls    bool
@@ -60,24 +62,35 @@ func defaults(cfg *config) {
 }
 
 func clientDefaults(cfg *config) {
-	cfg.serviceName = namingschema.NewDefaultServiceName(
+	sn := namingschema.NewDefaultServiceName(
 		defaultClientServiceName,
 		namingschema.WithOverrideV0(defaultClientServiceName),
 	).GetName()
+	cfg.serviceName = func() string { return sn }
 	cfg.spanName = namingschema.NewGRPCClientOp().GetName()
 	defaults(cfg)
 }
 
 func serverDefaults(cfg *config) {
-	cfg.serviceName = namingschema.NewDefaultServiceName(defaultServerServiceName).GetName()
+	// We check for a configured service name, so we don't break users who are incorrectly creating their server
+	// before the call `tracer.Start()`
+	if globalconfig.ServiceName() != "" {
+		sn := namingschema.NewDefaultServiceName(defaultServerServiceName).GetName()
+		cfg.serviceName = func() string { return sn }
+	} else {
+		log.Warn("No global service name was detected. GRPC Server may have been created before calling tracer.Start(). Will dynamically fetch service name for every span. " +
+			"Note this may have a slight performance cost, it is always recommended to start the tracer before initializing any traced packages.\n")
+		ns := namingschema.NewDefaultServiceName(defaultServerServiceName)
+		cfg.serviceName = ns.GetName
+	}
 	cfg.spanName = namingschema.NewGRPCServerOp().GetName()
 	defaults(cfg)
 }
 
 // WithServiceName sets the given service name for the intercepted client.
 func WithServiceName(name string) Option {
 	return func(cfg *config) {
-		cfg.serviceName = name
+		cfg.serviceName = func() string { return name }
 	}
 }