Refactor Telemetry Initialization and Environment Utilities (#811)

* improve code for metrics

* improve code for metrics

* fix

* fix

* Refactor telemetry initialization and environment functions ordering

- Reorder functions in envs.rs by type size (8-bit to 64-bit, signed before unsigned) and add missing variants like get_env_opt_u16.
- Optimize init_telemetry to support three modes: stdout logging (default error level with span tracing), file rolling logs (size-based with retention), and HTTP-based observability with sub-endpoints (trace, metric, log) falling back to unified endpoint.
- Fix stdout logging issue by retaining WorkerGuard in OtelGuard to prevent premature release of async writer threads.
- Enhance observability mode with HTTP protocol, compression, and proper resource management.
- Update OtelGuard to include tracing_guard for stdout and flexi_logger_handles for file logging.
- Improve error handling and configuration extraction in OtelConfig.

* fix

* up

* fix

* fix

* improve code for obs

* fix

* fix

rustfs/src/main.rs

@@ -89,7 +89,6 @@ const LOGO: &str = r#"
 #[instrument]
 fn print_server_info() {
     let current_year = chrono::Utc::now().year();
-
     // Use custom macros to print server information
     info!("RustFS Object Storage Server");
     info!("Copyright: 2024-{} RustFS, Inc", current_year);
@@ -112,10 +111,13 @@ async fn async_main() -> Result<()> {
     init_license(opt.license.clone());
 
     // Initialize Observability
-    let guard = init_obs(Some(opt.clone().obs_endpoint)).await;
-
-    // print startup logo
-    info!("{}", LOGO);
+    let guard = match init_obs(Some(opt.clone().obs_endpoint)).await {
+        Ok(g) => g,
+        Err(e) => {
+            println!("Failed to initialize observability: {}", e);
+            return Err(Error::other(e));
+        }
+    };
 
     // Store in global storage
     match set_global_guard(guard).map_err(Error::other) {
@@ -126,6 +128,9 @@ async fn async_main() -> Result<()> {
         }
     }
 
+    // print startup logo
+    info!("{}", LOGO);
+
     // Initialize performance profiling if enabled
     #[cfg(not(target_os = "windows"))]
     profiling::init_from_env().await;