From 83faf24b3367b5daf84d47c374c7dcae85ab5071 Mon Sep 17 00:00:00 2001
From: Heikki Hellgren <heikki.hellgren@op.fi>
Date: Wed, 31 Jul 2024 07:46:33 +0300
Subject: [PATCH] feat: add possibility to allow and deny specific email
 addresses

Notification email processor config to support allowing and denying
specific email addresses who can receive notifications in email.
This is required to be able to test this in test environments with real
production data and not send unnecessary notifications.

Signed-off-by: Heikki Hellgren <heikki.hellgren@op.fi>
---
 .changeset/witty-queens-run.md                |  5 ++++
 .../config.d.ts                               |  8 ++++++
 .../processor/NotificationsEmailProcessor.ts  | 27 +++++++++++++++++--
 3 files changed, 38 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/witty-queens-run.md

diff --git a/.changeset/witty-queens-run.md b/.changeset/witty-queens-run.md
new file mode 100644
index 0000000000..2d869caa91
--- /dev/null
+++ b/.changeset/witty-queens-run.md
@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-notifications-backend-module-email': patch
+---
+
+Notification email processor supports allowing or denying specific email addresses from receiving notifications
diff --git a/plugins/notifications-backend-module-email/config.d.ts b/plugins/notifications-backend-module-email/config.d.ts
index 92f3385d1b..e4ce5ede53 100644
--- a/plugins/notifications-backend-module-email/config.d.ts
+++ b/plugins/notifications-backend-module-email/config.d.ts
@@ -132,6 +132,14 @@ export interface Config {
            */
           excludedTopics?: string[];
         };
+        /**
+         * White list of addresses to send email to
+         */
+        allowlistEmailAddresses?: string[];
+        /**
+         * Black list of addresses to not send email to
+         */
+        denylistEmailAddresses?: string[];
       };
     };
   };
diff --git a/plugins/notifications-backend-module-email/src/processor/NotificationsEmailProcessor.ts b/plugins/notifications-backend-module-email/src/processor/NotificationsEmailProcessor.ts
index 3bfccfcc90..f3d9f59b8c 100644
--- a/plugins/notifications-backend-module-email/src/processor/NotificationsEmailProcessor.ts
+++ b/plugins/notifications-backend-module-email/src/processor/NotificationsEmailProcessor.ts
@@ -56,6 +56,8 @@ export class NotificationsEmailProcessor implements NotificationProcessor {
   private readonly throttleInterval: number;
   private readonly frontendBaseUrl: string;
   private readonly filter: NotificationProcessorFilters;
+  private readonly allowlistEmailAddresses?: string[];
+  private readonly denylistEmailAddresses?: string[];
 
   constructor(
     private readonly logger: LoggerService,
@@ -85,6 +87,12 @@ export class NotificationsEmailProcessor implements NotificationProcessor {
       ? durationToMilliseconds(readDurationFromConfig(cacheConfig))
       : 3_600_000;
     this.frontendBaseUrl = config.getString('app.baseUrl');
+    this.allowlistEmailAddresses = emailProcessorConfig.getOptionalStringArray(
+      'allowlistEmailAddresses',
+    );
+    this.denylistEmailAddresses = emailProcessorConfig.getOptionalStringArray(
+      'denylistEmailAddresses',
+    );
     this.filter = getProcessorFiltersFromConfig(emailProcessorConfig);
   }
 
@@ -197,10 +205,25 @@ export class NotificationsEmailProcessor implements NotificationProcessor {
     notification: Notification,
     options: NotificationSendOptions,
   ) {
+    let emails: string[];
     if (options.recipients.type === 'broadcast' || notification.user === null) {
-      return await this.getBroadcastEmails();
+      emails = await this.getBroadcastEmails();
+    } else {
+      emails = await this.getUserEmail(notification.user);
     }
-    return await this.getUserEmail(notification.user);
+
+    if (this.allowlistEmailAddresses) {
+      emails = emails.filter(email =>
+        this.allowlistEmailAddresses?.includes(email),
+      );
+    }
+
+    if (this.denylistEmailAddresses) {
+      emails = emails.filter(
+        email => !this.denylistEmailAddresses?.includes(email),
+      );
+    }
+    return emails;
   }
 
   private async sendMail(options: Mail.Options) {