feat: gracul shutdown of s3api and admin servers

Implements graceful shutdown for the admin and s3api servers. They are shut down before other components (IAM, s3logger, etc.) to allow the servers to properly handle any pending requests while dependencies are still active. The shutdown process is controlled by a context with a 10-second timeout. If it exceeds this duration, all remaining requests are forcefully terminated and the servers are closed.

cmd/versitygw/main.go

@@ -832,31 +832,36 @@ Loop:
 	}
 	saveErr := err
 
+	// first shut down the s3api and admin servers
+	// as they have dependecy from other modules
+	err = srv.ShutDown()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "shutdown api server: %v\n", err)
+	}
+
+	if admSrv != nil {
+		err := admSrv.Shutdown()
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "shutdown admin server: %v\n", err)
+		}
+	}
+
 	be.Shutdown()
 
 	err = iam.Shutdown()
 	if err != nil {
-		if saveErr == nil {
-			saveErr = err
-		}
 		fmt.Fprintf(os.Stderr, "shutdown iam: %v\n", err)
 	}
 
 	if loggers.S3Logger != nil {
 		err := loggers.S3Logger.Shutdown()
 		if err != nil {
-			if saveErr == nil {
-				saveErr = err
-			}
 			fmt.Fprintf(os.Stderr, "shutdown s3 logger: %v\n", err)
 		}
 	}
 	if loggers.AdminLogger != nil {
 		err := loggers.AdminLogger.Shutdown()
 		if err != nil {
-			if saveErr == nil {
-				saveErr = err
-			}
 			fmt.Fprintf(os.Stderr, "shutdown admin logger: %v\n", err)
 		}
 	}
@@ -864,9 +869,6 @@ Loop:
 	if evSender != nil {
 		err := evSender.Close()
 		if err != nil {
-			if saveErr == nil {
-				saveErr = err
-			}
 			fmt.Fprintf(os.Stderr, "close event sender: %v\n", err)
 		}
 	}