How to get the request headers from a grpc request in java?

Question

I'm building a Java grpc server and I'm having a hard time getting the request headers. The proto files are compiled using protobuf-maven-plugin, and based on the generated stubs, I can't access the context or the request metadata.

I've also tried to define a list of key/values in the message request, hoping the grpc will take care of the headers mappings, but no luck so far.

Any idea how I can get access the headers?

Thanks!

My proto files content:

...
// Version Request
message VersionRequest {
  // key/value pairs
  repeated Header headers = 1;
}

message Header {
  //key
  string key = 1;
  //value
  string constant = 2;
}
...



   ...
security_definitions: {
    security: {
      key: "clientIdAuth";
      value: {
        type: TYPE_API_KEY;
        in: IN_HEADER;
        name: "x-client-id";
      }
    }
    security: {
      key: "clientSecretAuth";
      value: {
        type: TYPE_API_KEY;
        in: IN_HEADER;
        name: "x-client-secret";
      }
    }
    security: {
      key: "bearerAuth";
      value: {
        type: TYPE_API_KEY;
        in: IN_HEADER;
        name: "Authorization";
      }
    }
  }
    ...
    // Retrieves system version
      //
      // Retrieves system version
      rpc GetVersion(VersionRequest) returns (Version) {
        option (google.api.http) = {
          get : "/api/v4/version"
        };
        option (grpc.gateway.protoc_gen_swagger.options.openapiv2_operation) = {
          security: {
            security_requirement: {
              key: "clientIdAuth";
              value: {}
            }
            security_requirement: {
              key: "clientSecretAuth";
              value: {}
            }
            security_requirement: {
              key: "bearerAuth";
              value: {}
            }
          }
        };
      }
    ...

The server side implementation looks like this:

...
@GrpcService
public class GrpcAPIService extends MixAPIGrpc.MixAPIImplBase {

    @Autowired
    private MwProxy mwProxy;

    @Override
    public void getVersion(VersionRequest versionRequest, StreamObserver<Version> streamObserver) {
        System.out.println("===============" + versionRequest.getHeadersCount());
        handleEGrpcCall("getVersion", mwProxy::getVersion, streamObserver);
    }
...

versionRequest.getHeadersCount() always returns 0, although there are 3 headers sent in all my requests.

user675693 user675693 · Accepted Answer · 2020-11-18T19:13:37

Unless you are using a custom grpc-java codegen plugin provided by a third party, the standard grpc codegen plugin shipped with grpc-java library https://search.maven.org/search?q=a:protoc-gen-grpc-java%20g:io.grpc does not support custom method options such as

option (grpc.gateway.protoc_gen_swagger.options.openapiv2_operation)

So you can not take advantage of that options. What grpc-java can do is to send and receive io.grpc.Metadata via client and server interceptors. See examples: https://github.com/grpc/grpc-java/tree/v1.33.1/examples/src/main/java/io/grpc/examples/header

How to get the request headers from a grpc request in java?

1 Answers