Support custom path prefix in gRPC service URL

Is your feature request related to a problem? Yes

The ask here is related to the following issue: https://github.com/grpc/grpc/issues/14900 We have following usecase:

We have multiple instances of the same gRPC server app running on multiple k8s deployments. Our routing model from gRPC client to gRPC servers is not direct but rather using Ingress with rerouting based on path

myserver/path1/myApi/call1 goes to instance1 myserver/path2/myApi/call1 goes to instance2 … myserver/pathN/myApi/call1 goes to instanceN

Now that nginx supports gRPC routing, this seems trivial to set up from the routing side. Alas, it does not seem to work. Since gRPC target and subsequently authority take only host:port into consideration

Number of destination servers is not finite as those come and go, so it’s not possible to have static Ingress spec

Possibly this is a gRPC client limitation?

Describe the solution you’d like

What we’d like to have is a way to specify path part in the target or any other header that will allow to produce HTTP2 URI that can be rerouted finalDestinationServer/myApi/call1

Describe alternatives you’ve considered

use REST instead of gRPC

Additional context

[ejona86]

Metadata.Key destinationServer = Metadata.Key.of("destination-server", Metadata.ASCII_STRING_MARSHALLER)

Metadata metadata = new Metadata();
metadata.put(destinationServer, "path2");
stub.withInterceptors(MetadataUtils.newAttachHeadersInterceptor(metadata)).someMethod();

I don’t have any snippet for k8s.

[yuliya-salesforce]

Are you using Java on both client and server

We are using Java for client and most likely Python for server

For header-based routing your client would add a piece of Metadata to the request, and then you’d configure the proxy to change the destination based on that header.

I see. So eventually it’s k8s setup of a proxy that would need to be header based If you have any Java example of the client and respective k8s setup - it would be great! (if you have it handy)