feat(main.go): actually detect instance path

main.go

@@ -13,7 +13,7 @@ import (
 
 func main() {
 	running := true
-	instance_path, err := filepath.Abs("/home/pauljako/boundaries")
+	instance_path, err := get_instance_path()
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -80,3 +80,27 @@ func accept_clients(ln *net.Listener, instance *string, running *bool) {
 		}()
 	}
 }
+
+func get_instance_path() (string, error) {
+	if len(os.Args) == 2 {
+		return filepath.Abs(os.Args[1])
+	}
+
+	// When bndd has been started by boundaries, this can be used to get the instance it used
+	app_dir, has := os.LookupEnv("APP_DIR")
+	if has {
+		return filepath.Abs(filepath.Join(app_dir, "..", ".."))
+	}
+
+	// Fallback to the user-path
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return "", err
+	}
+	home_instance_path, err := filepath.Abs(filepath.Join(home, "boundaries"))
+	if exists, err := exists(home_instance_path); exists && err == nil {
+		return home_instance_path, nil
+	}
+
+	return "", errors.New("no suitable instance path found")
+}