# Build Version Information into Your Rust Binary

To help us disect the problem from a deployed binary, it will be useful to build some information like git-commit hash, build date, etc.

Use [`vergen`](https://crates.io/crates/vergen) to generate a list of `env` during building.

You have to add `vergen` into `Cargo.toml`.

[package]
build = "build.rs"

[build-dependencies]
anyhow = "1.0.69"
vergen = { version = "7.5.1", features = ["build", "git"] }

Since we are using these packages in `build.rs` instead of `src/*.rs`, we should specify each version of the packages in the `build-dependencies` section.

After setting up the `Cargo.toml`, prepare a `build.rs`:

use anyhow::Result;
use vergen::{vergen, Config};

fn main() -> Result<()> {
    vergen(Config::default())
}

Then we can retrieve the enviroment variables in our source code

fn main() {
    println!("build from commit {}", env!["VERGEN_GIT_SHA"]);
}

###### tags: `rust`