在服务器端如何读取 gRPC 中的元数据？（使用 Golang 示例）

huangapple
go评论116阅读模式
英文:

how to read metadata in grpc on the server side? (golang example)

问题

在gRPC的服务器端如何读取作为头部传递的元数据？有没有使用golang的示例？

我正在编写类似以下的代码：

// 这应该从客户端作为上下文传递，并需要在服务器端访问以读取元数据
var headers = metadata.New(map[string]string{"authorization": "", "space": "", "org": "", "limit": "", "offset": ""})

我想将授权令牌传递给我的验证函数，以验证接收到的令牌。

func validate_token(ctx context.Context, md *metadata.MD) (context.Context, error){
token := headers["authorization"]
}

英文:

How to read metadata (passed as a header) on the server side in grpc? Any example in golang?

I am writing something like this:

  1. // this should be passed from the client side as a context and needs to accessed on server side to read the metadata
  2. var headers = metadata.New(map[string]string{"authorization": "", "space":  "", "org": "", "limit": "", "offset": ""})

I want to pass the Authorization token to my validation function to validate the received token.

  1. func validate_token(ctx context.Context, md *metadata.MD) (context.Context, error){
  2.     token := headers["authorization"]
  3. }

答案1

得分: 40

在调用服务器之前，您需要将元数据插入客户端的上下文中。

对于一元RPC，客户端代码如下：

  1. conn, _ := grpc.Dial(address, opts...)
  2. client := NewMyClient(conn) // 使用grpc protoc选项从您的proto生成
  4. header := metadata.New(map[string]string{"authorization": "", "space": "", "org": "", "limit": "", "offset": ""})
  5. // 这是包含您的标头的关键步骤
  6. ctx := metadata.NewContext(context.Background(), header)
  8. request := // 构造您的服务的请求
  9. response, err := client.MyMethod(ctx, request)

对于流式传输，代码几乎相同：

  1. conn, _ := grpc.Dial(address, opts...)
  2. client := NewMyClient(conn) // 使用grpc protoc选项从您的proto生成
  4. header := metadata.New(map[string]string{"authorization": "", "space": "", "org": "", "limit": "", "offset": ""})
  5. // 这是包含您的标头的关键步骤
  6. ctx := metadata.NewContext(context.Background(), header)
  7. stream, err := client.MyMethodStream(ctx)
  9. for {
  10.     request :=  // 构造您的服务的请求
  11.     err := stream.Send(request)
  12.     response := new(Response)
  13.     err = stream.RecvMsg(response)
  14. }

对于一元RPC的服务器端代码：

  1. func (s myServer) MyMethod(context.Context, *Request) (*Response, error) {
  2.     md, ok := metadata.FromIncomingContext(ctx)
  3.     token := md.Get("authorization")[0] // metadata.Get返回键的值数组
  4. }

对于流式RPC：

  1. func (s myServer) MyMethodStream(stream MyMethod_MyServiceStreamServer) error {
  2.     md, ok := metadata.FromIncomingContext(stream.Context())
  3.     token := md.Get("authorization")[0] // metadata.Get返回键的值数组
  4.     for {
  5.         request := new(Request)
  6.         err := stream.RecvMsg(request)
  7.         response := // 处理工作
  8.         err := stream.SendMsg(response)
  9.     }
  10. }

请注意，对于流式传输，只有三种情况可以发送标头：在用于打开初始流的上下文中，通过grpc.SendHeader和grpc.SetTrailer。无法在流中的任意消息上设置标头。对于一元RPC，标头将与每个消息一起发送，并且可以在初始上下文中、使用grpc.SendHeader和grpc.SetHeader以及grpc.SetTrailer中设置。

英文:

You have to insert your metadata into the client's context before calling the server.

For an unary RPC the client side looks like:

  1. conn, _ := grpc.Dial(address, opts...)
  2. client := NewMyClient(conn) // generated from your proto with the grpc protoc option
  4. header := metadata.New(map[string]string{"authorization": "", "space":  "", "org": "", "limit": "", "offset": ""})
  5. // this is the critical step that includes your headers
  6. ctx := metadata.NewContext(context.Background(), header)
  8. request := // construct a request for your service
  9. response, err := client.MyMethod(ctx, request)

For a stream, it looks almost the same:

  1. conn, _ := grpc.Dial(address, opts...)
  2. client := NewMyClient(conn) // generated from your proto with the grpc protoc option
  4. header := metadata.New(map[string]string{"authorization": "", "space":  "", "org": "", "limit": "", "offset": ""})
  5. // this is the critical step that includes your headers
  6. ctx := metadata.NewContext(context.Background(), header)
  7. stream, err := client.MyMethodStream(ctx)
  9. for {
  10.     request :=  // construct a request for your service
  11.     err := stream.Send(request)
  12.     response := new(Response)
  13.     err = stream.RecvMsg(response)
  14. }

On the server side for an unary RPC:

  1. func (s myServer) MyMethod(context.Context, *Request) (*Response, error) {
  2.     md, ok := metadata.FromIncomingContext(ctx)
  3.     token := md.Get("authorization")[0] // metadata.Get returns an array of values for the key
  4. }

and for a streaming RPC:

  1. func (s myServer) MyMethodStream(stream MyMethod_MyServiceStreamServer) error {
  2.     md, ok := metadata.FromIncomingContext(stream.Context())
  3.     token := md.Get("authorization")[0] // metadata.Get returns an array of values for the key
  4.     for {
  5.         request := new(Request)
  6.         err := stream.RecvMsg(request)
  7.         response := // do work
  8.         err := stream.SendMsg(response)
  9.     }
  10. }

Note that for a stream there are only three times that headers can be sent: in the context used to open the initial stream, via grpc.SendHeader, and grpc.SetTrailer. It is not possible to set headers on arbitrary messages in a stream. For an unary RPC header are sent with every message and can be set in the initial context, with grpc.SendHeader and grpc.SetHeader, and grpc.SetTrailer.

答案2

得分: 7

原始答案是正确的，但读取标头的方法已经过时。

  1. import "google.golang.org/grpc/metadata"
  3. func (s myServer) MyMethod(ctx context.Context, *Request) (*Response, error) {
  4.   var values []string
  5.   var token string
  7.   md, ok := metadata.FromIncomingContext(ctx)
  8.   if ok {
  9.     values = md.Get("authorization")
  10.   }
  12.   if len(values) > 0 {
  13.     token = values[0]
  14.   }
  16.   // 使用 token 做一些操作
  17. }
英文:

original answer is correct but reading the headers is slightly outdated

  1. import "google.golang.org/grpc/metadata"
  3. func (s myServer) MyMethod(ctx context.Context, *Request) (*Response, error) {
  4.   var values []string
  5.   var token string
  7.   md, ok := metadata.FromIncomingContext(ctx)
  8.   if ok {
  9.     values = md.Get("authorization")
  10.   }
  12.   if len(values) > 0 {
  13.     token = values[0]
  14.   }
  16.   // do something with token
  17. }

huangapple
  • 本文由 发表于 2017年2月8日 23:04:00
  • 转载请务必保留本文链接：https://go.coder-hub.com/42116642.html
  • go
  • grpc
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