first commit

backend/internal/pkg/sysutil/restart.go

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+// Package sysutil provides system-level utilities for process management.
+package sysutil
+
+import (
+	"log"
+	"os"
+	"runtime"
+	"time"
+)
+
+// RestartService triggers a service restart by gracefully exiting.
+//
+// This relies on systemd's Restart=always configuration to automatically
+// restart the service after it exits. This is the industry-standard approach:
+//   - Simple and reliable
+//   - No sudo permissions needed
+//   - No complex process management
+//   - Leverages systemd's native restart capability
+//
+// Prerequisites:
+//   - Linux OS with systemd
+//   - Service configured with Restart=always in systemd unit file
+func RestartService() error {
+	if runtime.GOOS != "linux" {
+		log.Println("Service restart via exit only works on Linux with systemd")
+		return nil
+	}
+
+	log.Println("Initiating service restart by graceful exit...")
+	log.Println("systemd will automatically restart the service (Restart=always)")
+
+	// Give a moment for logs to flush and response to be sent
+	go func() {
+		time.Sleep(100 * time.Millisecond)
+		os.Exit(0)
+	}()
+
+	return nil
+}
+
+// RestartServiceAsync is a fire-and-forget version of RestartService.
+// It logs errors instead of returning them, suitable for goroutine usage.
+func RestartServiceAsync() {
+	if err := RestartService(); err != nil {
+		log.Printf("Service restart failed: %v", err)
+		log.Println("Please restart the service manually: sudo systemctl restart sub2api")
+	}
+}