# tonic-build

Compiles proto files via prost and generates service stubs and proto definitiones for use with tonic.

## Features

- rustfmt: This feature enables the use of rustfmt to format the output code this makes the code readable and the error messages nice. This requires that rustfmt is installed. This is enabled by default.

Required dependencies

```toml
[dependencies]
tonic = <tonic-version>
prost = <prost-version>

[build-dependencies]
tonic-build = <tonic-version>
```

## Examples

### Simple

In `build.rs`:
```rust
fn main() -> Result<(), Box<dyn std::error::Error>> {
    tonic_build::compile_protos("proto/service.proto")?;
    Ok(())
}
```

### Configuration

```rust
fn main() -> Result<(), Box<dyn std::error::Error>> {
    tonic_build::configure()
        .disable_package_emission()
        .codec("application/grpc | application/grpc+proto", "tonic::codec::ProstCodec")
        .codec("application/json | application/grpc+json", "crate::lib::codec::JsonCodec")
        .type_attribute(".", "#[derive(serde_derive::Deserialize, serde_derive::Serialize)]")
        .compile(&["proto/helloworld.proto", "proto/helpcenter.proto"],&["proto"])?;
    Ok(())
}
```

### Google APIs example
A good way to use Google API is probably using git submodules.

So suppose in our `proto` folder we do:
```
git submodule add https://github.com/googleapis/googleapis

git submodule update --remote
```

And a bunch of Google proto files in structure will be like this:
```
├── googleapis
│   └── google
│       ├── api
│       │   ├── annotations.proto
│       │   ├── client.proto
│       │   ├── field_behavior.proto
│       │   ├── http.proto
│       │   └── resource.proto
│       └── pubsub
│           └── v1
│               ├── pubsub.proto
│               └── schema.proto
```

Then we can generate Rust code via this setup in our `build.rs`
```rust
fn main() {
    tonic_build::configure()
        .build_server(false)
        //.out_dir("src/google")  // you can change the generated code's location
        .compile(
            &["proto/googleapis/google/pubsub/v1/pubsub.proto"],
            &["proto/googleapis"], // specify the root location to search proto dependencies
        ).unwrap();
}
```

Then you can reference the generated Rust like this this in your code:
```rust
pub mod api {
    tonic::include_proto!("google.pubsub.v1");
}
use api::{publisher_client::PublisherClient, ListTopicsRequest};
```

Or if you want to save the generated code in your own code base,
you can uncomment the line `.out_dir(...)` above, and in your lib file
config a mod like this:
```rust
pub mod google {
    #[path = ""]
    pub mod pubsub {
        #[path = "google.pubsub.v1.rs"]
        pub mod v1;
    }
}
```
See [the example here](https://github.com/hyperium/tonic/tree/master/examples/src/gcp)