intercept/docs/WEBHOOKS.md

Webhooks & Alert Notifications

INTERCEPT has a built-in alert engine that fires webhooks when decoded events match configurable rules. Forward pager messages (or events from any other mode) to Discord, Slack, n8n, Home Assistant, or any HTTP endpoint.

How it works

1. Configure alert rules in the Alerts UI — each rule defines which mode and event type to watch, optional match criteria, and a severity level.
2. When an incoming event matches a rule, INTERCEPT stores it in the alert log and POSTs a JSON payload to your configured webhook URL.
3. All modes are supported: pager, sensor, ADS-B, AIS, ACARS, WiFi, Bluetooth, and more.

Configuration

Set these environment variables in your .env file or docker-compose.yml:

Variable	Default	Description
ALERT_WEBHOOK_URL	(empty)	URL to POST alert payloads to
ALERT_WEBHOOK_SECRET	(empty)	Optional token sent as X-Alert-Token header
ALERT_WEBHOOK_TIMEOUT	5	HTTP timeout in seconds

ALERT_WEBHOOK_URL=https://your-endpoint.example.com/intercept-alerts
ALERT_WEBHOOK_SECRET=mysecrettoken

Creating alert rules

1. Open the Alerts panel in INTERCEPT
2. Click New Rule
3. Configure:
   • Mode: pager (or any other mode, or leave blank to match all)
   • Event type: message for pager decodes (or blank to match all event types)
   • Match criteria: leave empty to forward everything, or add filters (e.g. capcode equals 1234567, or message contains FIRE)
   • Severity: low, medium, or high
4. Save and enable the rule

Webhook payload format

{
  "id": 42,
  "rule_id": 1,
  "mode": "pager",
  "event_type": "message",
  "severity": "medium",
  "title": "My Pager Rule",
  "message": "message | 1234567",
  "created_at": "2026-04-13T10:00:00+00:00",
  "payload": {
    "mode": "pager",
    "event_type": "message",
    "event": {
      "capcode": "1234567",
      "message": "UNIT 4 RESPOND TO 123 MAIN ST",
      "type": "POCSAG1200"
    },
    "rule": { "id": 1, "name": "My Pager Rule" }
  }
}

Sending to Discord

Discord webhooks expect a different JSON format, so you need a relay between INTERCEPT and Discord.

Option A — No-code relay (recommended)

Use n8n, Make, or Pipedream to receive INTERCEPT's webhook and forward it to Discord with a custom message template. Point ALERT_WEBHOOK_URL at your workflow's ingest URL.

Option B — Self-hosted Python relay

Save as discord_relay.py and run it alongside INTERCEPT:

from flask import Flask, request
import urllib.request, json

app = Flask(__name__)

DISCORD_WEBHOOK_URL = "https://discord.com/api/webhooks/YOUR_ID/YOUR_TOKEN"

@app.post("/relay")
def relay():
    data = request.get_json(force=True)
    mode = data.get("mode", "unknown").upper()
    title = data.get("title", "Alert")
    message = data.get("message", "")
    event = data.get("payload", {}).get("event", {})

    lines = [f"**[{mode}]** {title}", message]
    if event.get("capcode"):
        lines.append(f"Capcode: `{event['capcode']}`")
    if event.get("type"):
        lines.append(f"Protocol: {event['type']}")

    payload = json.dumps({"content": "\n".join(lines)}).encode()
    req = urllib.request.Request(
        DISCORD_WEBHOOK_URL,
        data=payload,
        headers={"Content-Type": "application/json"},
        method="POST",
    )
    urllib.request.urlopen(req, timeout=5)
    return "", 204

app.run(host="0.0.0.0", port=5051)

Set ALERT_WEBHOOK_URL=http://localhost:5051/relay and run: python3 discord_relay.py

Filtering specific capcodes

To only forward decodes from a specific capcode, set the rule's Match criteria:

Field	Operator	Value
capcode	equals	1234567

Multiple rules can coexist — e.g. one rule for all pager traffic and a second rule for emergency capcodes with high severity routed to a separate channel.