Add ADR

adr/013-monitoring-notifications.md

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+# Architecture Decision Record: Monitoring Notifications
+
+Initial Author: Taha Hawa
+
+Initial Date: 2025-06-26
+
+Last Updated Date: 2025-06-26
+
+## Status
+
+Proposed
+
+## Context
+
+We need to send notifications (typically from AlertManager/Prometheus) and we need to receive said notifications on mobile devices for sure in some way, whether it's push messages, SMS, phone call, email, etc or all of the above.
+
+## Decision
+
+We should go with https://ntfy.sh except host it ourselves.
+
+`ntfy` is an open source solution written in Go that has the features we need.
+
+## Rationale
+
+`ntfy` has pretty much everything we need (push notifications, email forwarding, receives via webhook), and nothing/not much we don't. Good fit, lightweight.
+
+## Consequences
+
+Pros:
+
+- topics, with ACLs
+- lightweight
+- reliable
+- easy to configure
+- mobile app
+  - the mobile app can listen via websocket, poll, or receive via Firebase/GCM on Android, or similar on iOS.
+- Forward to email
+- Text-to-Speech phone call messages using Twilio integration
+- Operates based on simple HTTP requests/Webhooks, easily usable via AlertManager
+
+Cons:
+
+- No SMS pushes
+- SQLite DB, makes it harder to HA/scale
+
+## Alternatives considered
+
+[AWS SNS](https://aws.amazon.com/sns/):
+Pros:
+
+- highly reliable
+- no hosting needed
+
+Cons:
+
+- no control, not self hosted
+- costs (per usage)
+
+[Apprise](https://github.com/caronc/apprise):
+Pros:
+
+- Way more ways of sending notifications
+- Can use ntfy as one of the backends/ways of sending
+
+Cons:
+
+- Way too overkill for what we need in terms of features
+
+[Gotify](https://github.com/gotify/server):
+Pros:
+
+- simple, lightweight, golang, etc
+
+Cons:
+
+- Pushes topics are per-user
+
+## Additional Notes