---
title: "Crons"
description: "Sentry Crons allows you to monitor the uptime and performance of any scheduled, recurring job in your application."
url: https://docs.sentry.io/platforms/javascript/guides/react-router/crons/
---

# Set Up Crons | Sentry for React Router Framework

Once implemented, it'll allow you to get alerts and metrics to help you solve errors, detect timeouts, and prevent disruptions to your service.

## [Requirements](https://docs.sentry.io/platforms/javascript/guides/react-router/crons.md#requirements-1)

To begin monitoring your recurring, scheduled job:

1. [Create a new monitor](https://sentry.io/issues/alerts/new/crons/) in Sentry.
2. Configure check-ins or a heartbeat for your job.

Optionally, you can skip the first step and [create or update (upsert) a monitor through a check-in](https://docs.sentry.io/platforms/javascript/guides/react-router/crons.md#creating-or-updating-a-monitor-through-a-check-in-optional). See more below.

## [Check-Ins (Recommended)](https://docs.sentry.io/platforms/javascript/guides/react-router/crons.md#check-ins-recommended)

Check-in monitoring allows you to track a job's progress by completing two check-ins: one at the start of your job and another at the end of your job. This two-step process allows Sentry to notify you if your job didn't start when expected (missed) or if it exceeded its maximum runtime (failed).

```bash
SENTRY_INGEST="https://___ORG_INGEST_DOMAIN___"
SENTRY_CRONS="${SENTRY_INGEST}/api/___PROJECT_ID___/cron/<monitor_slug>/___PUBLIC_KEY___/"

# 🟡 Notify Sentry your job is running:
curl "${SENTRY_CRONS}?status=in_progress"

# Execute your scheduled task here...

# 🟢 Notify Sentry your job has completed successfully:
curl "${SENTRY_CRONS}?status=ok"
```

If your job execution fails:

```bash
# 🔴 Notify Sentry your job has failed:
curl "${SENTRY_CRONS}?status=error"
```

If you expect your scheduled jobs to overlap, read about [Overlapping Jobs](https://docs.sentry.io/platforms/javascript/guides/react-router/crons.md#overlapping-jobs-optional) below.

### [Specifying monitor environments (Optional)](https://docs.sentry.io/platforms/javascript/guides/react-router/crons.md#specifying-monitor-environments-optional)

When sending check-ins to your monitor you may specify the `environment` of the check-in. This allows you to monitor a single schedule across multiple environments.

If you don't specify an environment with your check-ins the default is `production`.

Monitor environments are still early in development. Currently, after a check-in occurs for a specific environment, you must continue sending check-ins on schedule or delete the monitor environment; otherwise, it will be marked as missed.

```bash
SENTRY_INGEST="https://___ORG_INGEST_DOMAIN___"
SENTRY_CRONS="${SENTRY_INGEST}/api/___PROJECT_ID___/cron/<monitor_slug>/___PUBLIC_KEY___/"

# 🟡 Notify Sentry your job is running in the dev environment:
curl "${SENTRY_CRONS}?environment=dev&status=in_progress"

# Execute your scheduled task here...

# 🟢 Notify Sentry your dev environment job has completed successfully:
curl "${SENTRY_CRONS}?environment=dev&status=ok"
```

### [Creating or Updating a Monitor Through a Check-In (Optional)](https://docs.sentry.io/platforms/javascript/guides/react-router/crons.md#creating-or-updating-a-monitor-through-a-check-in-optional)

Sentry enables the automatic creation or update of a monitor (upsert) through the check-in payload. This can be useful if you have many scheduled tasks or need to create them dynamically.

```bash
SENTRY_INGEST="https://___ORG_INGEST_DOMAIN___"
SENTRY_CRONS="${SENTRY_INGEST}/api/___PROJECT_ID___/cron/<monitor_slug>/___PUBLIC_KEY___/"

# 🟡 Notify Sentry your job is running:
curl -X POST "${SENTRY_CRONS}" \
    --header 'Content-Type: application/json' \
    --data-raw '{"monitor_config": {"schedule": {"type": "crontab", "value": "0 * * * *"}}, "status": "in_progress"}'
```

Monitor `monitor_config` parameters:

`schedule_type`:

The schedule representation for your monitor, either `crontab` or `interval`.

`schedule`:

The job's schedule :

This is an object specifying a `schedule_type` of either `crontab` or `interval`. The structure will vary depending on the type:

```json
{"type": "crontab", "value": "0 * * * *"}
{"type": "interval", "value": "2", "unit": "hour"}
```

`checkin_margin`:

The amount of time (in minutes) Sentry should wait for your check-in before it's considered missed ("grace period"). Optional.

We recommend that your check-in margin be less than or equal to your interval.

`max_runtime`:

The amount of time (in minutes) your job is allowed to run before it's considered failed. Optional.

`failure_issue_threshold`:

The number of consecutive failed check-ins it takes before an issue is created. Optional.

`recovery_threshold`:

The number of consecutive OK check-ins it takes before an issue is resolved. Optional.

`timezone`

The `tz` where your job is running. This is usually your server's timezone, (such as `America/Los_Angeles`). See [list of tz database time zones](https://en.wikipedia.org/wiki/List_of_tz_database_time_zones). Optional.

It's important to provide a timezone for non-repeating crontab schedules, such as `0 17 * * *` (every day at 5pm).

### [Overlapping Jobs (Optional)](https://docs.sentry.io/platforms/javascript/guides/react-router/crons.md#overlapping-jobs-optional)

A job execution that begins before the previous job execution has been completed is called an overlapping job. This happens if you have a job with a runtime duration longer than your job's interval schedule.

A simple example is if you have a job that runs every minute (1), but takes five (5) minutes to complete each execution.

If this happens, you have to provide a stable check-in ID for your execution with each request to prevent unintended consequences.

Usage example:

```bash
CHECK_IN_ID="$(uuidgen)"

SENTRY_INGEST="https://___ORG_INGEST_DOMAIN___"
SENTRY_CRONS="${SENTRY_INGEST}/api/___PROJECT_ID___/cron/<monitor_slug>/___PUBLIC_KEY___/"

# 🟡 Notify Sentry your job is running with a check-in ID:
curl "${SENTRY_CRONS}?check_in_id=${CHECK_IN_ID}&status=in_progress"

# Execute your scheduled task here...

# 🟢 Notify Sentry your job has completed successfully with a check-in ID:
curl "${SENTRY_CRONS}?check_in_id=${CHECK_IN_ID}&status=ok"
```

## [Heartbeat](https://docs.sentry.io/platforms/javascript/guides/react-router/crons.md#heartbeat)

Heartbeat monitoring notifies Sentry of a job's status through one check-in. This setup will only notify you if your job didn't start when expected (missed). If you need to track a job to see if it exceeded its maximum runtime (failed), use check-ins instead.

```bash
SENTRY_INGEST="https://___ORG_INGEST_DOMAIN___"
SENTRY_CRONS="${SENTRY_INGEST}/api/___PROJECT_ID___/cron/<monitor_slug>/___PUBLIC_KEY___/"

# 🟢 Notify Sentry your job has completed successfully:
curl "${SENTRY_CRONS}?status=ok"
```

If your job execution fails:

```bash
# 🔴 Notify Sentry your job has failed:
curl "${SENTRY_CRONS}?status=error"
```

## [Alerts](https://docs.sentry.io/platforms/javascript/guides/react-router/crons.md#alerts)

When your recurring job fails to check in (missed), runs beyond its configured maximum runtime (failed), or manually reports a failure, Sentry will create an error event with a tag to your monitor.

To receive alerts about these events:

1. Navigate to **Alerts** in the sidebar.
2. Create a new alert and select "Issues" under "Errors" as the alert type.
3. Configure your alert and define a filter match to use: `The event's tags match {key} {match} {value}`.

Example: `The event's tags match monitor.slug equals my-monitor-slug-here`

Learn more in [Issue Alert Configuration](https://docs.sentry.io/product/alerts/create-alerts/issue-alert-config.md).

## [Rate Limits](https://docs.sentry.io/platforms/javascript/guides/react-router/crons.md#rate-limits)

To prevent abuse and resource overuse, Crons limits check-ins to **6 per minute for each monitor environment**.

For example, if you have a monitor called "database-backup" with two environments:

* `database-backup` in environment `production` can send up to 6 check-ins per minute
* `database-backup` in environment `staging` can also send up to 6 check-ins per minute
* Combined, they can send up to 12 check-ins per minute

You can verify if any check-ins are being dropped by visiting the [Usage Stats](https://docs.sentry.io/product/stats.md#usage-stats) page. To avoid dropped check-ins, ensure your monitors don't exceed the rate limit.

## Pages in this section

- [Troubleshooting](https://docs.sentry.io/platforms/javascript/guides/react-router/crons/troubleshooting.md)