`fetch-source`

Declare external source dependencies in Cargo.toml and fetch them programmatically.

This crate allows you to define external sources (Git repositories, tar archives) in your Cargo.toml under [package.metadata.fetch-source] and fetch them programmatically. This crate is intended for use in build scripts where Rust bindings are generated from external source(s).

Inspired by CMake's FetchContent module.

Core Features

Define sources directly in your project metadata.
Cache fetched sources for efficient sharing between projects.
Clone git repositories (possibly recursively) by branch, tag, or specific commit (requires git to be installed and available on PATH).

Optional Features

tar: Download and extract .tar.gz archives. This is an optional feature because it uses the reqwest crate which brings quite a few more dependencies.
rayon: Fetch sources in parallel with rayon.

Basic Usage

Parse external sources declared in your Cargo.toml like so:

let cargo_toml = r#"
[package.metadata.fetch-source]
my-repo = { git = "https://github.com/user/repo.git", recursive = true }
other-repo = { git = "https://github.com/user/project.git", branch = "the-feature" }
my-data = { tar = "https://example.com/data.tar.gz" }
"#;

for (name, source) in fetch_source::try_parse_toml(cargo_toml)? {
    println!("{name}: {source}");
}

Fetch all sources into a directory:

use std::path::PathBuf;

let cargo_toml = r#"
[package.metadata.fetch-source]
"syn::latest" = { git = "https://github.com/dtolnay/syn.git" }
"syn::1.0.0" = { tar = "https://github.com/dtolnay/syn/archive/refs/tags/1.0.0.tar.gz" }
"#;

let out_dir = PathBuf::from(std::env::temp_dir());
for err in fetch_source::try_parse_toml(cargo_toml)?.into_iter()
    .map(|(_, source)| source.fetch(&out_dir))
    .filter_map(Result::err) {
    eprintln!("{err}");
}

License

Licensed under either of

Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.