Schedule a Cron Task - Iii

Goal

Run a Function at regular intervals (cleanup jobs, report generation, health checks) using the Cron module.

Steps

1. Enable the Cron module

yaml

modules:
  - class: modules::cron::CronModule
    config:
      adapter:
        class: modules::cron::KvCronAdapter

2. Register the Function

<Tabs> <Tab title="Node / TypeScript"> ```typescript title="cron-task.ts" import { registerWorker, Logger } from 'iii-sdk'

const iii = registerWorker(process.env.III_URL ?? 'ws://localhost:49134')

iii.registerFunction({ id: 'cleanup::expired-sessions' }, async () => { const logger = new Logger() // ...cleanup logic here... logger.info('Cleanup ran', { timestamp: new Date().toISOString() }) return { deleted: 0 } })

</Tab>
<Tab title="Python">
```python title="cron_task.py"
import os

from iii import Logger, register_worker

iii = register_worker(os.environ.get("III_URL", "ws://localhost:49134"))


def cleanup_sessions(_):
    logger = Logger()
    # ...cleanup logic here...
    logger.info("Cleanup ran")
    return {"deleted": 0}


iii.register_function({"id": "cleanup::expired-sessions"}, cleanup_sessions)

</Tab> <Tab title="Rust"> ```rust title="cron_task.rs" use iii_sdk::{register_worker, InitOptions, Logger, RegisterFunctionMessage, RegisterTriggerInput}; use serde_json::json; use tokio::signal;

#[tokio::main] async fn main() -> Result<(), Box<dyn std::error::Error>> { let url = std::env::var("III_URL").unwrap_or_else(|_| "ws://127.0.0.1:49134".to_string()); let iii = register_worker(&url, InitOptions::default());

iii.register_function(
    RegisterFunctionMessage {
        id: "cleanup::expired-sessions".into(),
        description: None,
        request_format: None,
        response_format: None,
        metadata: None,
        invocation: None,
    },
    |_| async move {
        let logger = Logger::new();
        // ...cleanup logic here...
        logger.info("Cleanup ran", None);
        Ok(json!({ "deleted": 0 }))
    },
);

signal::ctrl_c().await?;
Ok(())

}

</Tab>
</Tabs>

### 3. Register the Cron trigger

<Tabs>
<Tab title="Node / TypeScript">
```typescript title="cron-trigger.ts"
iii.registerTrigger({
  type: 'cron',
  function_id: 'cleanup::expired-sessions',
  config: { expression: '* * * * * * *' }, // runs every second
})

</Tab> <Tab title="Python"> ```python title="cron_trigger.py" iii.register_trigger({ "type": "cron", "function_id": "cleanup::expired-sessions", "config": {"expression": "* * * * * * *"}, # runs every second }) ``` </Tab> <Tab title="Rust"> ```rust title="cron_trigger.rs" iii.register_trigger(RegisterTriggerInput { trigger_type: "cron".into(), function_id: "cleanup::expired-sessions".into(), config: json!({ "expression": "* * * * * * *" }), // runs every second })?; ``` </Tab> </Tabs>

This runs the Function every second. The expression field uses a 7-field cron format with seconds support (second minute hour day month weekday year).

Common schedules

Expression	Frequency
`* * * * * * *`	Every second
`0 * * * * * *`	Every minute
`0 /5 * * * *`	Every 5 minutes
`0 0 * * * * *`	Every hour
`0 0 /6 * * *`	Every 6 hours
`0 0 0 * * * *`	Daily at midnight
`0 0 9 * * 1 *`	Every Monday at 9 AM

Result

The Function executes automatically on the defined schedule. The Engine handles scheduling, no external cron daemon needed. {/* <Info title="See also"> For advanced scheduling options, see the Cron module reference. </Info> */}