> ## Documentation Index
> Fetch the complete documentation index at: https://docs.screenjson.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Notifications

> Multi-driver notification fan-out — Slack, Teams, Discord, FCM, APNs, SNS, WebPush.

Beyond [webhooks](/tools/greenlight/webhooks), Greenlight can fan job-lifecycle events out to a set of human-facing notification channels. Each driver is optional; enable by setting the relevant environment variables.

## Runtime shape

| Variable                | Default | Description                                                                  |
| ----------------------- | ------- | ---------------------------------------------------------------------------- |
| `NOTIFY_QUEUE_SIZE`     | `256`   | Internal bounded buffer; beyond this, events are dropped with a warning log. |
| `NOTIFY_TIMEOUT`        | `8s`    | Per-driver request timeout.                                                  |
| `NOTIFY_MAX_RETRY`      | `4`     | Retry cap.                                                                   |
| `NOTIFY_RETRY_MIN_WAIT` | `1s`    | Initial back-off.                                                            |
| `NOTIFY_RETRY_MAX_WAIT` | `30s`   | Max back-off.                                                                |

## Slack

```bash theme={null}
NOTIFY_SLACK_WEBHOOK_URLS=https://hooks.slack.com/services/T000/B000/xxxx,https://hooks.slack.com/services/T111/B111/yyyy
```

Comma-separated list. Every URL receives every event.

## Microsoft Teams

```bash theme={null}
NOTIFY_TEAMS_WEBHOOK_URLS=https://outlook.office.com/webhook/...
```

## Discord

```bash theme={null}
NOTIFY_DISCORD_WEBHOOK_URLS=https://discord.com/api/webhooks/...
```

## Firebase Cloud Messaging

Mobile push on Android (and iOS if you've set up FCM there).

| Variable                   | Description                    |
| -------------------------- | ------------------------------ |
| `NOTIFY_FCM_SERVER_KEY`    | FCM legacy server key.         |
| `NOTIFY_FCM_DEVICE_TOKENS` | Comma-separated device tokens. |

## Apple Push Notification service (APNs)

iOS push.

| Variable                       | Description                                                                |
| ------------------------------ | -------------------------------------------------------------------------- |
| `NOTIFY_APNS_KEY_ID`           | APNs key id.                                                               |
| `NOTIFY_APNS_TEAM_ID`          | Apple Developer team id.                                                   |
| `NOTIFY_APNS_BUNDLE_ID`        | Topic bundle id.                                                           |
| `NOTIFY_APNS_PRIVATE_KEY`      | PEM key inline.                                                            |
| `NOTIFY_APNS_PRIVATE_KEY_FILE` | PEM key file path (alternative to inline).                                 |
| `NOTIFY_APNS_DEVICE_TOKENS`    | Comma-separated device tokens.                                             |
| `NOTIFY_APNS_PRODUCTION`       | `true` for the production APNs environment; `false` (default) for sandbox. |

## AWS SNS

Event fan-out to SNS topics.

| Variable                | Description                 |
| ----------------------- | --------------------------- |
| `NOTIFY_SNS_REGION`     | AWS region.                 |
| `NOTIFY_SNS_TOPIC_ARNS` | Comma-separated topic ARNs. |

## WebPush

Browser push (Chrome, Firefox, Edge, Safari 16+).

| Variable                            | Description                                                    |
| ----------------------------------- | -------------------------------------------------------------- |
| `NOTIFY_WEBPUSH_SUBJECT`            | `mailto:...` or URL the subscriber can contact.                |
| `NOTIFY_WEBPUSH_PUBLIC_KEY`         | VAPID public key.                                              |
| `NOTIFY_WEBPUSH_PRIVATE_KEY`        | VAPID private key.                                             |
| `NOTIFY_WEBPUSH_SUBSCRIPTIONS_JSON` | JSON array of push subscription objects (or a path to a file). |

## Delivery semantics

* All drivers are fire-and-forget from the worker's perspective.
* A dedicated goroutine pool drains the notification queue.
* Failures retry up to `NOTIFY_MAX_RETRY` times with the configured back-off; then they are logged and dropped.
* No ordering guarantees across drivers — the same event may reach Slack before Teams, or vice versa.