feat: add COMMIT_HASH build time env var

build.rs

@@ -0,0 +1,17 @@
+use std::process::Command;
+
+fn main() {
+    let commit_hash = match std::env::var("COMMIT_HASH") {
+        Ok(commit_hash_string) => commit_hash_string,
+        Err(_) => {
+            match Command::new("git")
+                .args(vec!["rev-parse", "--short", "HEAD"])
+                .output()
+            {
+                Ok(x) => String::from_utf8_lossy(x.stdout.trim_ascii_end()).into_owned(),
+                Err(_) => "no hash :(".to_string(),
+            }
+        }
+    };
+    println!("cargo::rustc-env=COMMIT_HASH=\"{}\"", commit_hash);
+}