fix: replace vergen by directly running git

For some reason, `vergen` was unable to find the git binary when
building inside Ansible. Running git directly fixes the problem... and
we also have one dependency less! 🎉

ci-bench-runner/Cargo.toml

@@ -31,6 +31,3 @@ uuid = { version = "1.4.1", features = ["v4", "serde"] }
 ctor = "0.2.5"
 reqwest = { version = "0.11.22", default-features = false, features = ["rustls-tls-webpki-roots"] }
 wiremock = "0.5.19"
-
-[build-dependencies]
-vergen = { version = "8.2.6", features = ["git", "gitcl"] }

ci-bench-runner/build.rs

@@ -1,11 +1,26 @@
+use std::process::Command;
+
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     // In some cases if new migrations are added without accompanying Rust src changes
     // `cargo build` isn't smart enough to detect the need for recompilation to pick up
     // the new embedded migrations. This build script is the recommended workaround.
     // See <https://docs.rs/sqlx/latest/sqlx/macro.migrate.html#triggering-recompilation-on-migration-changes>
     println!("cargo:rerun-if-changed=migrations");
 
-    // Expose git-related information through environment variables at compile-time
-    vergen::EmitBuilder::builder().all_git().emit()?;
+    // Trigger recompilation if the repository's head changed, to make sure the commit information
+    // embedded in the binary is up-to-date.
+    println!("cargo:rerun-if-changed=.git/HEAD");
+
+    // Expose git head information through environment variables at compile-time
+    let output = Command::new("git").args(["rev-parse", "HEAD"]).output()?;
+    let git_sha = String::from_utf8(output.stdout)?;
+    println!("cargo:rustc-env=GIT_HEAD_SHA={}", git_sha);
+
+    let output = Command::new("git")
+        .args(["show-branch", "--no-name", "HEAD"])
+        .output()?;
+    let git_commit_message = String::from_utf8(output.stdout)?;
+    println!("cargo:rustc-env=GIT_HEAD_COMMIT_MESSAGE={git_commit_message}");
+
     Ok(())
 }

ci-bench-runner/src/lib.rs

@@ -136,8 +136,8 @@ pub async fn server(
 /// Returns git commit information about the binary that is currently deployed
 async fn get_server_info() -> Json<serde_json::Value> {
     Json(json!({
-        "git_commit_sha": env!("VERGEN_GIT_SHA").to_string(),
-        "git_commit_message": env!("VERGEN_GIT_COMMIT_MESSAGE").to_string(),
+        "git_commit_sha": env!("GIT_HEAD_SHA").to_string(),
+        "git_commit_message": env!("GIT_HEAD_COMMIT_MESSAGE").to_string(),
     }))
 }