Refactor initializing tracing-subscriber

examples/prometheus-metrics/src/main.rs

@@ -21,7 +21,6 @@ use std::{
     net::SocketAddr,
     time::{Duration, Instant},
 };
-use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt};
 
 fn metrics_app() -> Router {
     let recorder_handle = setup_metrics_recorder();
@@ -65,12 +64,11 @@ async fn start_metrics_server() {
 
 #[tokio::main]
 async fn main() {
-    tracing_subscriber::registry()
-        .with(tracing_subscriber::EnvFilter::new(
-            std::env::var("RUST_LOG")
+    tracing_subscriber::fmt()
+        .with_env_filter(
+            tracing_subscriber::EnvFilter::try_from_default_env()
                 .unwrap_or_else(|_| "example_todos=debug,tower_http=debug".into()),
-        ))
-        .with(tracing_subscriber::fmt::layer())
+        )
         .init();
 
     // The `/metrics` endpoint should not be publicly available. If behind a reverse proxy, this