feat: add posibility to use token file in hetzner config

internal/server/server.go

@@ -106,9 +106,10 @@ func NewRouter(cfg *config.Config) *gin.Engine {
 			c.JSON(http.StatusForbidden, gin.H{"status": "error", "message": "host not authorized"})
 			return
 		}
-		prov, ok := selectProvider(cfg)
-		if !ok {
-			c.JSON(http.StatusInternalServerError, gin.H{"status": "error", "message": "provider not configured"})
+		prov, err := selectProvider(cfg)
+		if err != nil {
+			logger.Error("provider selection failed", zap.Error(err))
+			c.JSON(http.StatusInternalServerError, gin.H{"status": "error", "message": "provider configuration error"})
 			return
 		}
 		if err := prov.UpdateRecord(c.Request.Context(), req.Host, ip); err != nil {
@@ -126,12 +127,12 @@ func NewRouter(cfg *config.Config) *gin.Engine {
 
 // StartServer initializes Provider and starts the HTTP server.
 func StartServer(cfg *config.Config) error {
-	prov, ok := selectProvider(cfg)
-	if !ok {
-		return fmt.Errorf("unsupported provider: %s", cfg.Upstream.Provider)
+	// Provider selection happens within the request handler now to handle potential config errors per request
+	// We could pre-validate the provider config here, but deferring allows checking file existence/permissions closer to use.
+	// A simple check that the provider *name* is supported is still useful.
+	if _, supported := configToProviderName(cfg.Upstream.Provider); !supported {
+		return fmt.Errorf("unsupported provider name in config: %q", cfg.Upstream.Provider)
 	}
-	// drop unused to avoid compile error
-	_ = prov
 
 	router := NewRouter(cfg)
 	if cfg.Server.TLS.Enabled {
@@ -140,12 +141,33 @@ func StartServer(cfg *config.Config) error {
 	return router.Run(cfg.Server.BindAddress)
 }
 
-// selectProvider returns the configured Provider or false if unsupported.
-func selectProvider(cfg *config.Config) (pvd.Provider, bool) {
-	switch cfg.Upstream.Provider {
+// configToProviderName checks if a provider name from the config is known.
+// This is a simple check before attempting full provider initialization.
+func configToProviderName(providerName string) (string, bool) {
+	switch providerName {
 	case "hetzner":
-		return hetzner.NewProvider(cfg.Upstream.Hetzner.APIToken), true
+		return "hetzner", true
 	default:
-		return nil, false
+		return "", false
+	}
+}
+
+// selectProvider returns the configured Provider or an error if initialization fails.
+func selectProvider(cfg *config.Config) (pvd.Provider, error) {
+	providerName, supported := configToProviderName(cfg.Upstream.Provider)
+	if !supported {
+		return nil, fmt.Errorf("unsupported provider: %s", cfg.Upstream.Provider)
+	}
+
+	switch providerName {
+	case "hetzner":
+		prov, err := hetzner.NewProvider(cfg.Upstream.Hetzner)
+		if err != nil {
+			return nil, fmt.Errorf("initializing hetzner provider: %w", err)
+		}
+		return prov, nil
+	default:
+		// This case should technically be unreachable due to the check above
+		return nil, fmt.Errorf("internal error: unsupported provider %s passed initial check", providerName)
 	}
 }