prostbuild

prost-build is a Rust library that generates Rust code from Protocol Buffer (.proto) files at build time as part of the Prost ecosystem. It is designed to be used alongside Prost, a Protocol Buffers implementation for Rust, and with tools like tonic for gRPC services. prost-build reads .proto definitions and produces Rust types representing messages, enums, and oneof constructs, with options to customize the generated code.

To use prost-build, developers add it as a build-dependency in Cargo.toml and provide a build script (build.rs) that configures and runs the generator. The common workflow calls prost_build::compile_protos with a list of proto files and include directories. A Config object can be used to customize the output, for example to map well-known types to external crates via extern_path, or to attach attributes to generated types through type_attribute.

The generated Rust source files are written to the crate’s OUT_DIR during compilation. The crate then includes these generated modules with include!(concat!(env!("OUT_DIR"), "/<generated>.rs"));, allowing the generated code to be compiled as part of the crate without occupying the main source tree.

prost-build focuses on generating message types and related code, and does not itself emit gRPC service stubs. For gRPC service generation, developers typically use tonic-build in conjunction with prost-build to generate both message types and service definitions.