品牌网站建设解决方,电商网店运营,物联网软件开发平台,教育培训机构加盟go-zero 的网关往 rpc 服务传递数据时#xff0c;可以使用 headers#xff0c;但需要注意前缀规则#xff0c;否则会发现数据传递不过去#xff0c;或者对方取不到数据。
go-zero 的网关对服务的调用使用了第三方库 grpcurl#xff0c;入口函数为 InvokeRPC#xff1a; …go-zero 的网关往 rpc 服务传递数据时可以使用 headers但需要注意前缀规则否则会发现数据传递不过去或者对方取不到数据。
go-zero 的网关对服务的调用使用了第三方库 grpcurl入口函数为 InvokeRPC
grpcurl.InvokeRPC(r.Context(), source, cli.Conn(), rpcPath, s.prepareMetadata(r.Header), handler, parser.Next)调用在 https://github.com/zeromicro/go-zero/blob/master/gateway/server.go 中进行的上述调用会处理 HTTP 的 headers 数据对于不是以字符串“Grpc-Metadata-”打头的会过滤掉对于以字符串“Grpc-Metadata-”打头的会将“Grpc-Metadata-”转为“gateway-”。
// go-zero/gateway/internal/headerprocessor.go
// ProcessHeaders builds the headers for the gateway from HTTP headers.
func ProcessHeaders(header http.Header) []string {var headers []stringfor k, v : range header {if !strings.HasPrefix(k, metadataHeaderPrefix) { // 判断是否包含了前缀“Grpc-Metadata-”continue // 如果没有前缀“Grpc-Metadata-”则直接过滤丢弃掉}// 将前缀“Grpc-Metadata-”替换为前缀“gateway-”key : fmt.Sprintf(%s%s, metadataPrefix, strings.TrimPrefix(k, metadataHeaderPrefix))for _, vv : range v {headers append(headers, key:vv)}}return headers
}函数 MetadataFromHeaders 负责从 headers 解码数据
// https://github.com/fullstorydev/grpcurl/blob/master/grpcurl.go
func MetadataFromHeaders(headers []string) metadata.MD {md : make(metadata.MD)for _, part : range headers {if part ! {pieces : strings.SplitN(part, :, 2)if len(pieces) 1 {pieces append(pieces, ) // if no value was specified, just make it (maybe the header value doesnt matter)}headerName : strings.ToLower(strings.TrimSpace(pieces[0]))val : strings.TrimSpace(pieces[1])if strings.HasSuffix(headerName, -bin) {if v, err : decode(val); err nil {val v}}md[headerName] append(md[headerName], val)}}return md
}// https://github.com/fullstorydev/grpcurl/blob/master/invoke.go
func InvokeRPC(ctx context.Context, source DescriptorSource, ch grpcdynamic.Channel, methodName string,headers []string, handler InvocationEventHandler, requestData RequestSupplier) error {md : MetadataFromHeaders(headers)svc, mth : parseSymbol(methodName)if svc || mth {return fmt.Errorf(given method name %q is not in expected format: service/method or service.method, methodName)}dsc, err : source.FindSymbol(svc)if err ! nil {// return a gRPC status error if hasStatus is trueerrStatus, hasStatus : status.FromError(err)switch {case hasStatus isNotFoundError(err):return status.Errorf(errStatus.Code(), target server does not expose service %q: %s, svc, errStatus.Message())case hasStatus:return status.Errorf(errStatus.Code(), failed to query for service descriptor %q: %s, svc, errStatus.Message())case isNotFoundError(err):return fmt.Errorf(target server does not expose service %q, svc)}return fmt.Errorf(failed to query for service descriptor %q: %v, svc, err)}sd, ok : dsc.(*desc.ServiceDescriptor)if !ok {return fmt.Errorf(target server does not expose service %q, svc)}mtd : sd.FindMethodByName(mth)if mtd nil {return fmt.Errorf(service %q does not include a method named %q, svc, mth)}handler.OnResolveMethod(mtd)// we also download any applicable extensions so we can provide full support for parsing user-provided datavar ext dynamic.ExtensionRegistryalreadyFetched : map[string]bool{}if err fetchAllExtensions(source, ext, mtd.GetInputType(), alreadyFetched); err ! nil {return fmt.Errorf(error resolving server extensions for message %s: %v, mtd.GetInputType().GetFullyQualifiedName(), err)}if err fetchAllExtensions(source, ext, mtd.GetOutputType(), alreadyFetched); err ! nil {return fmt.Errorf(error resolving server extensions for message %s: %v, mtd.GetOutputType().GetFullyQualifiedName(), err)}msgFactory : dynamic.NewMessageFactoryWithExtensionRegistry(ext)req : msgFactory.NewMessage(mtd.GetInputType())handler.OnSendHeaders(md)ctx metadata.NewOutgoingContext(ctx, md)stub : grpcdynamic.NewStubWithMessageFactory(ch, msgFactory)ctx, cancel : context.WithCancel(ctx)defer cancel()if mtd.IsClientStreaming() mtd.IsServerStreaming() {return invokeBidi(ctx, stub, mtd, handler, requestData, req)} else if mtd.IsClientStreaming() {return invokeClientStream(ctx, stub, mtd, handler, requestData, req)} else if mtd.IsServerStreaming() {return invokeServerStream(ctx, stub, mtd, handler, requestData, req)} else {return invokeUnary(ctx, stub, mtd, handler, requestData, req)}
}网关可如下实现
newReq : r.WithContext(r.Context())
newReq.Header.Set(Grpc-Metadata-myuid, userId)
next.ServeHTTP(w, newReq)服务端的实现
vals : metadata.ValueFromIncomingContext(l.ctx, gateway-myuid)
userId : vals[0]
