[新增] 实现安全兜底配置功能，允许在无历史配置时启动 OpenResty 并返回 503 状态

openflare_agent/internal/nginx/manager.go

@@ -155,6 +155,25 @@ const (
 	ApplyStatusFatal   ApplyStatus = "fatal"
 )
 
+const safeDefaultFallbackMainConfig = `# This file is generated by OpenFlare safe default fallback.
+worker_processes auto;
+pid logs/nginx.pid;
+
+events {
+    worker_connections 1024;
+}
+
+http {
+    default_type text/plain;
+
+    server {
+        listen 80 default_server;
+        server_name _;
+        return 503 "OpenFlare: No Valid Configuration\n";
+    }
+}
+`
+
 type ApplyOutcome struct {
 	Status  ApplyStatus
 	Message string
@@ -219,7 +238,18 @@ func (m *Manager) rollbackAfterFailedApply(ctx context.Context, backup *backupSt
 		return fatalApplyOutcome(fmt.Errorf("restore openresty backup failed after apply error %v: %w", applyErr, err))
 	}
 	if err := m.activateConfig(ctx); err != nil {
-		return fatalApplyOutcome(fmt.Errorf("apply failed: %v; rollback recovery failed: %w", applyErr, err))
+		if backup != nil && backup.MainExisted {
+			return fatalApplyOutcome(fmt.Errorf("apply failed: %v; rollback recovery failed: %w", applyErr, err))
+		}
+		if fallbackErr := m.EnsureSafeFallbackRuntime(ctx, fmt.Sprintf("apply failed: %v; rollback recovery failed: %v", applyErr, err)); fallbackErr != nil {
+			return fatalApplyOutcome(fmt.Errorf("apply failed: %v; rollback recovery failed: %w; fallback recovery failed: %v", applyErr, err, fallbackErr))
+		}
+		message := fmt.Sprintf("apply failed, but fallback runtime started: %v; rollback recovery failed: %v", applyErr, err)
+		slog.Warn("openresty apply recovered with safe default fallback", "message", message)
+		return ApplyOutcome{
+			Status:  ApplyStatusWarning,
+			Message: message,
+		}
 	}
 	message := fmt.Sprintf("apply failed, rolled back to previous config: %v", applyErr)
 	slog.Warn("openresty apply rolled back successfully", "message", message)
@@ -276,6 +306,25 @@ func (m *Manager) EnsureRuntime(ctx context.Context, recreate bool) error {
 	return m.Executor.EnsureRuntime(ctx, recreate)
 }
 
+func (m *Manager) EnsureSafeFallbackRuntime(ctx context.Context, reason string) error {
+	if m.Executor == nil {
+		return errors.New("executor 未配置")
+	}
+	trimmedReason := strings.TrimSpace(reason)
+	if trimmedReason == "" {
+		trimmedReason = "no valid local openresty config is available"
+	}
+	slog.Warn("starting openresty safe default fallback runtime", "reason", trimmedReason)
+	if err := m.writeSafeDefaultFallbackFiles(); err != nil {
+		return fmt.Errorf("write safe default fallback config failed: %w", err)
+	}
+	if err := m.activateConfig(ctx); err != nil {
+		return fmt.Errorf("activate safe default fallback runtime failed: %w", err)
+	}
+	slog.Warn("openresty safe default fallback runtime started", "main_config", m.MainConfigPath, "route_config", m.RouteConfigPath)
+	return nil
+}
+
 func (m *Manager) CheckHealth(ctx context.Context) error {
 	if m.Executor == nil {
 		return errors.New("executor 未配置")
@@ -675,6 +724,28 @@ func (m *Manager) restorePowConfig(state *backupState) error {
 	return os.WriteFile(configPath, []byte(state.PowConfig.Content), 0o644)
 }
 
+func (m *Manager) writeSafeDefaultFallbackFiles() error {
+	if strings.TrimSpace(m.MainConfigPath) == "" {
+		return errors.New("main config path 不能为空")
+	}
+	if strings.TrimSpace(m.RouteConfigPath) == "" {
+		return errors.New("route config path 不能为空")
+	}
+	if err := os.MkdirAll(filepath.Dir(m.MainConfigPath), 0o755); err != nil {
+		return err
+	}
+	if err := os.MkdirAll(filepath.Dir(m.RouteConfigPath), 0o755); err != nil {
+		return err
+	}
+	if err := os.WriteFile(m.RouteConfigPath, nil, 0o644); err != nil {
+		return err
+	}
+	if err := os.WriteFile(m.MainConfigPath, []byte(safeDefaultFallbackMainConfig), 0o644); err != nil {
+		return err
+	}
+	return nil
+}
+
 func removeLegacyPowConfig(path string) error {
 	if strings.TrimSpace(path) == "" {
 		return nil