Add git compile-time information

Cargo.toml

@@ -89,6 +89,7 @@ tracing-test = "0.2"
 tonic-build = { version = "0.6.0", default_features = false, features = ["transport", "prost"] }
 # Locked to 0.8 to match `tonic-build`'s `prost-build`.
 prost-build = "=0.9.0"
+built = { version = "0.5.1", features = ["git2"] }
 
 [features]
 instrument = []

build.rs

@@ -81,5 +81,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
         println!("cargo:rerun-if-changed={}", path.to_str().unwrap());
     }
 
+    built::write_built_file().expect("Failed to acquire build-time information");
+
     Ok(())
 }

src/main.rs

@@ -76,7 +76,7 @@ async fn main() -> quilkin::Result<()> {
         tracing_subscriber::fmt().json().with_target(false).init();
     }
 
-    info!(version = &*version, "Starting Quilkin");
+    info!(version = &*version, commit = quilkin::metadata::build::GIT_COMMIT_HASH, "Starting Quilkin");
     match cli.command {
         Commands::Run => {
             let config = std::fs::File::open(cli.config)

src/metadata.rs

@@ -18,6 +18,11 @@ use std::{collections::HashMap, convert::TryFrom, sync::Arc};
 
 use crate::xds::config::core::v3::Metadata as ProtoMetadata;
 
+#[doc(hidden)]
+pub mod build {
+   include!(concat!(env!("OUT_DIR"), "/built.rs"));
+}
+
 /// Shared state between [`Filter`][crate::filters::Filter]s during processing for a single packet.
 pub type DynamicMetadata = HashMap<Arc<String>, Value>;