Using tonic

Microsoft’s akri uses tonic to provide gRPC.

For the gRPC Health-checking Protocol proto:

./proto/grpc_health_v1.proto:

syntax = "proto3";

package grpc.health.v1;

service Health {
    rpc Check(HealthCheckRequest) returns (HealthCheckResponse);
  
    rpc Watch(HealthCheckRequest) returns (stream HealthCheckResponse);
  }
message HealthCheckRequest {
  string service = 1;
}

message HealthCheckResponse {
  enum ServingStatus {
    UNKNOWN = 0;
    SERVING = 1;
    NOT_SERVING = 2;
    SERVICE_UNKNOWN = 3;  // Used only by the Watch method.
  }
  ServingStatus status = 1;
}

Tonic supports compiling protos using build.rs:

fn main() -> Result<(), Box<dyn std::error::Error>> {
     // compile refers to the path
    tonic_build::compile_protos("proto/grpc_health_v1.proto")?;

    Ok(())
}

And then useing these:

pub mod grpc_health_v1 {
    // include refers to the package
    tonic::include_proto!("grpc.health.v1");
}
use grpc_health_v1::{
    health_check_response::ServingStatus,
    health_server::{Health, HealthServer},
    HealthCheckRequest, HealthCheckResponse,
};