Add warnings when features are not included in build

src/db/lib.rs

@@ -2,6 +2,9 @@
 #[cfg(feature = "sqlite")]
 extern crate tracing;
 
+#[cfg(not(any(feature = "lmdb", feature = "sled", feature = "sqlite")))]
+compile_error!("Must activate the Cargo feature for at least one DB engine: lmdb, sled or sqlite.");
+
 #[cfg(feature = "lmdb")]
 pub mod lmdb_adapter;
 #[cfg(feature = "sled")]

src/garage/server.rs

@@ -114,6 +114,11 @@ pub async fn run_server(config_file: PathBuf) -> Result<(), Error> {
 		));
 	}
 
+	#[cfg(not(feature = "metrics"))]
+	if config.admin_api.metrics_token.is_some() {
+		warn!("This Garage version is built without the metrics feature");
+	}
+
 	// Stuff runs
 
 	// When a cancel signal is sent, stuff stops