Introduce reflectMetadata

js/modules/k6/grpc/client.go

@@ -260,6 +260,9 @@ func (c *Client) Connect(addr string, params goja.Value) (bool, error) {
 	if !p.UseReflectionProtocol {
 		return true, nil
 	}
+
+	ctx = metadata.NewOutgoingContext(ctx, p.ReflectionMetadata)
+
 	fdset, err := c.conn.Reflect(ctx)
 	if err != nil {
 		return false, err
@@ -510,6 +513,7 @@ func newMetadata(input goja.Value) (metadata.MD, error) {
 
 type connectParams struct {
 	IsPlaintext           bool
+	ReflectionMetadata    metadata.MD
 	UseReflectionProtocol bool
 	Timeout               time.Duration
 	MaxReceiveSize        int64
@@ -521,6 +525,7 @@ func newConnectParams(rt *goja.Runtime, input goja.Value) (connectParams, error)
 	params := connectParams{
 		IsPlaintext:           false,
 		UseReflectionProtocol: false,
+		ReflectionMetadata:    metadata.New(nil),
 		Timeout:               time.Minute,
 		MaxReceiveSize:        0,
 		MaxSendSize:           0,
@@ -554,6 +559,12 @@ func newConnectParams(rt *goja.Runtime, input goja.Value) (connectParams, error)
 			if !ok {
 				return params, fmt.Errorf("invalid reflect value: '%#v', it needs to be boolean", v)
 			}
+		case "reflectMetadata":
+			md, err := newMetadata(raw.Get(k))
+			if err != nil {
+				return params, fmt.Errorf("invalid reflectMetadata param: %w", err)
+			}
+			params.ReflectionMetadata = md
 		case "maxReceiveSize":
 			var ok bool
 			params.MaxReceiveSize, ok = v.(int64)

js/modules/k6/grpc/client_test.go

@@ -13,6 +13,7 @@ import (
 	"google.golang.org/protobuf/reflect/protoreflect"
 	"google.golang.org/protobuf/reflect/protoregistry"
 	"google.golang.org/protobuf/types/known/wrapperspb"
+	"gopkg.in/guregu/null.v3"
 
 	"github.com/golang/protobuf/ptypes/any"
 	"github.com/golang/protobuf/ptypes/wrappers"
@@ -1193,3 +1194,46 @@ func TestClientLoadProto(t *testing.T) {
 		assert.Nil(t, err, "It was not expected that there would be an error, but it got: %v", err)
 	}
 }
+
+func TestClientConnectionReflectMetadata(t *testing.T) {
+	t.Parallel()
+
+	ts := newTestState(t)
+
+	reflection.Register(ts.httpBin.ServerGRPC)
+
+	initString := codeBlock{
+		code: `var client = new grpc.Client();`,
+	}
+	vuString := codeBlock{
+		code: `client.connect("GRPCBIN_ADDR", {reflect: true, reflectMetadata: {"x-test": "custom-header-for-reflection"}})`,
+	}
+
+	val, err := ts.Run(initString.code)
+	assertResponse(t, initString, err, val, ts)
+
+	ts.ToVUContext()
+
+	// this should trigger logging of the outgoing gRPC metadata
+	ts.VU.State().Options.HTTPDebug = null.NewString("full", true)
+
+	val, err = ts.Run(vuString.code)
+	assertResponse(t, vuString, err, val, ts)
+
+	entries := ts.loggerHook.Drain()
+
+	// since we enable debug logging, we should see the metadata in the logs
+	foundReflectionCall := false
+	for _, entry := range entries {
+		if strings.Contains(entry.Message, "ServerReflection/ServerReflectionInfo") {
+			foundReflectionCall = true
+
+			// check that the metadata is present
+			assert.Contains(t, entry.Message, "x-test: custom-header-for-reflection")
+			// check that user-agent header is present
+			assert.Contains(t, entry.Message, "user-agent: k6-test")
+		}
+	}
+
+	assert.True(t, foundReflectionCall, "expected to find a reflection call in the logs, but didn't")
+}