envoy: use envoy request id for logging across systems with http and gRPC (#691)

internal/telemetry/requestid/grpc_server.go

@@ -0,0 +1,56 @@
+package requestid
+
+import (
+	"context"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/metadata"
+)
+
+type grpcStream struct {
+	grpc.ServerStream
+	ctx context.Context
+}
+
+func (ss grpcStream) Context() context.Context {
+	return ss.ctx
+}
+
+// StreamServerInterceptor returns a new gRPC StreamServerInterceptor which populates the request id
+// from the incoming metadata.
+func StreamServerInterceptor() grpc.StreamServerInterceptor {
+	return func(srv interface{}, ss grpc.ServerStream, info *grpc.StreamServerInfo, handler grpc.StreamHandler) error {
+		ctx := ss.Context()
+		requestID := fromMetadata(ctx)
+		ctx = WithValue(ctx, requestID)
+		ss = grpcStream{
+			ServerStream: ss,
+			ctx:          ctx,
+		}
+		return handler(srv, ss)
+	}
+}
+
+// UnaryServerInterceptor returns a new gRPC UnaryServerInterceptor which populates the request id
+// from the incoming metadata.
+func UnaryServerInterceptor() grpc.UnaryServerInterceptor {
+	return func(ctx context.Context, req interface{}, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (resp interface{}, err error) {
+		requestID := fromMetadata(ctx)
+		ctx = WithValue(ctx, requestID)
+		return handler(ctx, req)
+	}
+}
+
+func fromMetadata(ctx context.Context) string {
+	md, ok := metadata.FromIncomingContext(ctx)
+	if !ok {
+		return New()
+	}
+
+	headers := md.Get(headerName)
+	if len(headers) == 0 || headers[0] == "" {
+		return New()
+	}
+
+	return headers[0]
+}