How to import .proto when working with prost and tonic in rust?

Question

I'm trying to build a simple gRPC client in rust using crates prost and tonic. My proto definitions are quite simple, but I suddenly stuck with using messages imported from other proto.

// file src/protos/types.proto
syntax = "proto3";
package Types;

message Message1 {
    uint32 value1 = 1;
    bytes value2 = 2;
}

message Message2 {
    uint32 value1 = 1;
    uint32 value2 = 2;
    uint32 value3 = 3;
    uint32 value4 = 4;
}

// file src/protos/service.proto
syntax = "proto3";
import "types.proto";
package Service;

service Worker {
    rpc Do (Request) returns (Reply);
}

message Request {
    Types.Message1 message1 = 1;
    Types.Message2 message2 = 2;
}

message Reply {
    bool success = 1;
}

My build.rs is very straightforward:

fn main() -> Result<(), Box<dyn std::error::Error>> {
    tonic_build::compile_protos("src/protos/types.proto")?;
    tonic_build::compile_protos("src/protos/service.proto")?;
    Ok(())
}

The problem begins when I including protos in main.rs:

pub mod service {
    tonic::include_proto!("types");
    tonic::include_proto!("service");
}

The compilation fails with the following error:

 --> D:\temp\rust-proto\target\debug\build\rust-proto-11c38604fbc7ce30\out/service.rs:4:48     
  |
4 |     pub message1: ::std::option::Option<super::types::Message1>,
  |                                                ^^^^^ maybe a missing crate `types`?

What might be wrong here?! I uploaded my playground project to github in case it might be useful.

Did you mean to tag this [tag:prost]? It's the only question with that tag. — David Buck, Aug 14 '20 at 21:22

score 10 · Accepted Answer · answered May 02 '20 at 05:45

10

I don't know much about tonic, but you must put the includes in modules corresponding to their proto packages, e.g.:

pub mod types {
    tonic::include_proto!("types");
}
pub mod service {
    tonic::include_proto!("service");
}

fn main() {
    let msg = types::Message1::default();
    println!("Hello, world! {:?}", msg);
}

This compiles correctly.

BTW, you can check the generated rust code at the following location in your setup here:

D:\temp\rust-proto\target\debug\build\rust-proto-11c38604fbc7ce30\out

answered May 02 '20 at 05:45

user1516867

311
2
4

Thanks! That's what I was missing: an every package must be in an own module. – ie. May 02 '20 at 16:26
I have a similar problem, although I'm using tonic_build::configure. Could you take a look at https://stackoverflow.com/questions/76646372/build-fails-with-could-not-find-proto-in-the-crate-root please. – Gaurav Gahlot Jul 09 '23 at 09:22

How to import .proto when working with prost and tonic in rust?

1 Answers1