Processors

Notifications can be extended with NotificationProcessor. These processors allow you to decorate notifications before they are sent and/or send the notifications to external services.

Depending on your needs, a processor can modify the content of a notification or route it to different systems like email, Slack, or other services.

A good example of how to write a processor is the Email Processor.

Start off by creating a notification processor:

import { Notification } from '@backstage/plugin-notifications-common';
import { NotificationProcessor } from '@backstage/plugin-notifications-node';

class MyNotificationProcessor implements NotificationProcessor {
  // preProcess is called before the notification is saved to database.
  // This is a good place to modify the notification before it is saved and sent to the user.
  async preProcess(notification: Notification): Promise<Notification> {
    if (notification.origin === 'plugin-my-plugin') {
      notification.payload.icon = 'my-icon';
    }
    return notification;
  }

  // postProcess is called after the notification is saved to database and the signal is emitted.
  // This is a good place to send the notification to external services.
  async postProcess(notification: Notification): Promise<void> {
    nodemailer.sendEmail({
      from: 'backstage',
      to: 'user',
      subject: notification.payload.title,
      text: notification.payload.description,
    });
  }
}

Both of the processing functions are optional, and you can just implement one of them.

Add the notification processor to the notification system by:

import { notificationsProcessingExtensionPoint } from '@backstage/plugin-notifications-node';
import { Notification } from '@backstage/plugin-notifications-common';

export const myPlugin = createBackendPlugin({
  pluginId: 'myPlugin',
  register(env) {
    env.registerInit({
      deps: {
        notifications: notificationsProcessingExtensionPoint,
        // ...
      },
      async init({ notifications }) {
        // ...
        notifications.addProcessor(new MyNotificationProcessor());
      },
    });
  },
});

Built-in Processors

Backstage comes with some processors that can be used immediately.

Email Processor

Email processor is used to send notifications to users using email. To install the email processor, add the @backstage/plugin-notifications-backend-module-email package to your backend.

yarn workspace backend add @backstage/plugin-notifications-backend-module-email

Add the email processor to your backend:

import { createBackend } from '@backstage/plugin-notifications-backend';
const backend = createBackend();
// ...
backend.add(import('@backstage/plugin-notifications-backend-module-email'));

To configure the email processor, you need to add the following configuration to your app-config.yaml:

notifications:
  email:
    smtp:
      host: smtp.example.com
      port: 587
      secure: false
      username: ${SMTP_USERNAME}
      password: ${SMTP_PASSWORD}

Apart from STMP, the email processor also supports the following transmissions:

• SES
• sendmail
• stream (only for debugging purposes)

See more information at https://github.com/backstage/backstage/blob/master/plugins/notifications-backend-module-email/README.md