Add simple master key provider for secret encryption

services/secrets/masterkey_nop.go

@@ -0,0 +1,43 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package secrets
+
+type nopMasterKeyProvider struct {
+}
+
+// NewNopMasterKeyProvider returns master key provider that holds no master key and is always unsealed
+func NewNopMasterKeyProvider() MasterKeyProvider {
+	return &nopMasterKeyProvider{}
+}
+
+// Init initializes master key provider
+func (k *nopMasterKeyProvider) Init() error {
+	return nil
+}
+
+// GenerateMasterKey always returns empty master key
+func (k *nopMasterKeyProvider) GenerateMasterKey() ([][]byte, error) {
+	return nil, nil
+}
+
+// Unseal master key by providing unsealing secret
+func (k *nopMasterKeyProvider) Unseal(secret []byte) error {
+	return nil
+}
+
+// Seal master key
+func (k *nopMasterKeyProvider) Seal() error {
+	return nil
+}
+
+// IsSealed always returns false
+func (k *nopMasterKeyProvider) IsSealed() bool {
+	return false
+}
+
+// GetMasterKey returns empty master key
+func (k *nopMasterKeyProvider) GetMasterKey() ([]byte, error) {
+	return nil, nil
+}