feat: support for stream transport for debug purposes

Signed-off-by: Heikki Hellgren <heikki.hellgren@op.fi>

.changeset/shy-games-poke.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-notifications-backend-module-email': patch
+---
+
+Add support for stream transport for debugging purposes

plugins/notifications-backend-module-email/README.md

@@ -2,7 +2,7 @@
 
 Adds support for sending Backstage notifications as emails to users.
 
-Supports sending emails using `SMTP`, `SES`, or `sendmail`.
+Supports sending emails using `SMTP`, `SES`, `sendmail`, or `stream` (for debugging purposes).
 
 ## Customizing email content
 

plugins/notifications-backend-module-email/config.d.ts

@@ -79,6 +79,10 @@ export interface Config {
                * Newline style, defaults to 'unix'
                */
               newline?: 'unix' | 'windows';
+            }
+          | {
+              /** Only for debugging, disables the actual sending of emails */
+              transport: 'stream';
             };
         /**
          * Sender email address

plugins/notifications-backend-module-email/src/processor/NotificationsEmailProcessor.ts

@@ -38,6 +38,7 @@ import {
   createSendmailTransport,
   createSesTransport,
   createSmtpTransport,
+  createStreamTransport,
 } from './transports';
 import { UserEntity } from '@backstage/catalog-model';
 import { compact } from 'lodash';
@@ -129,6 +130,8 @@ export class NotificationsEmailProcessor implements NotificationProcessor {
       );
     } else if (transport === 'sendmail') {
       this.transporter = createSendmailTransport(this.transportConfig);
+    } else if (transport === 'stream') {
+      this.transporter = createStreamTransport();
     } else {
       throw new Error(`Unsupported transport: ${transport}`);
     }
@@ -229,6 +232,7 @@ export class NotificationsEmailProcessor implements NotificationProcessor {
 
   private async sendMail(options: Mail.Options) {
     try {
+      this.logger.debug(`Sending notification email to ${options.to}`);
       await this.transporter.sendMail(options);
     } catch (e) {
       this.logger.error(`Failed to send email to ${options.to}: ${e}`);

plugins/notifications-backend-module-email/src/processor/transports/index.ts

@@ -16,3 +16,4 @@
 export { createSmtpTransport } from './smtp';
 export { createSesTransport } from './ses';
 export { createSendmailTransport } from './sendmail';
+export { createStreamTransport } from './stream';

plugins/notifications-backend-module-email/src/processor/transports/stream.ts

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2024 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import { createTransport } from 'nodemailer';
+
+export const createStreamTransport = () => {
+  return createTransport({ streamTransport: true });
+};