alerting

name

alerting

description

Configure and manage cron-monitor alert delivery to Slack, email, or webhook endpoints. Use when you need to set up notifications for failed or missed cron jobs, test alert delivery, or manage existing alert configurations. Triggers include "configure alerts", "set up Slack notification", "webhook alert", "email notification", "notify on failure", or any task involving alert routing for cron jobs.

alerting

Configure alert delivery for cron-monitor job failures and missed runs.

When to use

• Setting up Slack notifications for job failures
• Adding webhook delivery to an incident management system
• Configuring email alerts for on-call rotation
• Testing that alert delivery is working before relying on it

Alert Events

Event	When it fires
missed	No ping received within the job's grace period after its scheduled time
failure	A ping was received with status: "failure" or a non-zero exit code
recovery	A success ping received after a missed or failure state

Create a Slack alert via API

curl -s -X POST https://monitor.example.com/api/alerts \
  -H "Authorization: Bearer cm_..." \
  -H "Content-Type: application/json" \
  -d '{
    "channel": "slack",
    "target": "https://hooks.slack.com/services/T0.../B0.../xxxx",
    "onMissed": 1,
    "onFailure": 1,
    "onRecovery": 1,
    "cooldownMinutes": 60
  }'

To apply to a specific job only, include "jobId": "<uuid>". Omitting jobId applies to all jobs.

Create a webhook alert via API

curl -s -X POST https://monitor.example.com/api/alerts \
  -H "Authorization: Bearer cm_..." \
  -H "Content-Type: application/json" \
  -d '{
    "channel": "webhook",
    "target": "https://api.pagerduty.com/v2/enqueue",
    "onMissed": 1,
    "onFailure": 1,
    "onRecovery": 0,
    "cooldownMinutes": 30,
    "jobId": "550e8400-e29b-41d4-a716-446655440000"
  }'

Webhook payload format

POST to the target URL with JSON body and X-CM-Signature HMAC-SHA256 header:

{
  "event": "failure",
  "job": {
    "id": "550e8400-...",
    "name": "API Sync",
    "slug": "api-sync",
    "schedule": "*/5 * * * *"
  },
  "execution": {
    "id": "7f8a9b2c-...",
    "status": "failure",
    "exitCode": 1,
    "durationMs": 410,
    "finishedAt": "2026-03-20T15:52:14Z",
    "output": "Connection timeout"
  },
  "timestamp": "2026-03-20T15:52:20Z",
  "monitorUrl" 

Verify the signature:

const crypto = require('node:crypto');
const secret = 'cm_your_webhook_secret';
const signature = req.headers['x-cm-signature'];
const expected = crypto.createHmac('sha256', secret)
  .update(JSON.stringify(req.body))
  .digest('hex');
const valid = crypto.timingSafeEqual(
  Buffer.from(signature),
  Buffer.from(`sha256=${expected}`)
);

Test an alert

curl -s -X POST https://monitor.example.com/api/alerts/<id>/test \
  -H "Authorization: Bearer cm_..."
# Response: { "ok": true, "channel": "slack", "deliveredAt": "2026-03-20T16:00:00Z" }

List and manage alerts via API

# List all alert configs
curl -s https://monitor.example.com/api/alerts \
  -H "Authorization: Bearer cm_..."

# Update cooldown period
curl -s -X PATCH https://monitor.example.com/api/alerts/<id> \
  -H "Authorization: Bearer cm_..." \
  -H "Content-Type: application/json" \
  -d '{ "cooldownMinutes": 120 }'

# Delete
curl -s -X DELETE https://monitor.example.com/api/alerts/<id> \
  -H "Authorization: Bearer cm_..."

Cooldown behavior

The cooldownMinutes setting prevents alert storms. Once an alert fires for a job event, the same alert type will not fire again for that job until the cooldown period passes. Recovery events always fire regardless of cooldown.

Troubleshooting

Alert not firing

1. Check the job status in the dashboard - alert only fires on status transitions
2. Verify the alert config applies to the correct job (or all jobs)
3. Check onMissed/onFailure flags are set to 1
4. Check the cooldown: the same alert may be suppressed within the cooldown window

Webhook getting 401/403

The receiving endpoint may require auth headers. Use a proxy or middleware that adds auth before forwarding to your upstream. cron-monitor does not support custom request headers on webhook delivery.