wehub-resource-sync
44 lines
1.6 KiB
Plaintext
44 lines
1.6 KiB
Plaintext
---
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title: "Schedules: cron-triggered functions"
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description: "Run a function on a cron schedule using pg_cron"
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---
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Schedules invoke functions on a recurring cron expression. [pg_cron](https://github.com/citusdata/pg_cron) fires an HTTP request to the function URL at each tick and logs the result.
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## Concepts
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A schedule is a cron expression, a target URL, and headers. On creation, `${{secrets.KEY}}` placeholders in headers are resolved and encrypted with `pgcrypto`. At each tick, `execute_job()` decrypts headers, calls the function, and writes status and duration to `schedules.job_logs`.
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## Usage
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Standard 5-field cron (no seconds). Reference secrets in headers instead of hardcoding keys.
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```text
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*/5 * * * * every 5 minutes
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0 * * * * every hour
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0 0 * * * daily at midnight
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0 9 * * 1 every Monday at 9am
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0 0 1 * * first of every month
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```
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Create via dashboard or SQL:
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```sql
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select schedules.create_job(
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name => 'daily-cleanup',
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schedule => '0 0 * * *',
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url => 'https://myapp.functions.insforge.app/cleanup',
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headers => jsonb_build_object('Authorization', 'Bearer ${{secrets.CRON_TOKEN}}')
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);
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```
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## Limits
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Minimum interval is 1 minute (pg_cron). Failed runs are logged but not retried, so the function must be idempotent. Deleting a referenced secret breaks every job using it until you update or disable the schedule.
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## More resources
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- [pg_cron docs](https://github.com/citusdata/pg_cron) for cron syntax.
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- [Functions overview](/core-concepts/functions/overview) for the runtime.
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- [crontab.guru](https://crontab.guru) to check an expression.
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