protoc-fetcher

Rust library for fetching official Protocol Buffer compiler (protoc) releases, pegged to a specific version.

protoc-fetcher downloads an official [release] of the protobuf compiler (protoc) and returns the path to it.

```rust use std::env; use std::path::Path;

// From within build.rs... let protocversion = "21.5"; let outdir = env::var("OUTDIR").unwrap(); let protocpath = protocfetcher::protoc(protocversion, Path::new(&out_dir)); ```

The release archive matching the given version will be downloaded, and the protoc binary will be extracted into a subdirectory of out_dir. You can choose a version from the [release] page, for example "21.5". Don't prefix it with a "v".

out_dir can be anywhere you want, but if calling this function from a build script, you should probably use the OUT_DIR env var (which is set by Cargo automatically for build scripts).

A previously downloaded protoc binary of the correct version will be reused if already present in out_dir.

Usage with Tonic or Prost

If you are using [tonic-build] (or [prost-build]), you can instruct it to use the fetched protoc binary by setting the PROTOC env var.

```rust use std::env; use std::path::Path;

let outdir = env::var("OUTDIR").unwrap(); let pathtomyprotos = Path::new("a/b/c"); let protocpath = protocfetcher::protoc("21.2", Path::new(&outdir)).unwrap(); env::setvar("PROTOC", &protocpath); tonicbuild::compileprotos(pathtomy_protos); ```