Cron

Schedule functions to execute at specific times using cron expressions.

modules::cron::CronModule

Sample Configuration

- class: modules::cron::CronModule
  config:
    adapter:
      class: modules::cron::RedisCronAdapter
      config:
        redis_url: ${REDIS_URL:redis://localhost:6379}

Configuration

Adapter

The adapter to use for distributed locking. Defaults to modules::cron::KvCronAdapter. Use RedisCronAdapter for multi-instance deployments.

Adapters

modules::cron::KvCronAdapter

When running multiple engine instances, KvCronAdapter does not provide reliable distributed locking — the same cron job may execute on every instance simultaneously. Use RedisCronAdapter for multi-instance deployments.

Built-in adapter using process-local locks. Suitable for single-instance deployments.

class: modules::cron::KvCronAdapter
config:
  lock_ttl_ms: 30000
  lock_index: cron_locks

Configuration

integer

Duration in milliseconds for which a lock is held before it expires. Defaults to 30000 (30 seconds).

string

Key namespace used to store lock entries in the KV store. Defaults to cron_locks.

modules::cron::RedisCronAdapter

Uses Redis for distributed locking to prevent duplicate job execution across multiple engine instances.

class: modules::cron::RedisCronAdapter
config:
  redis_url: ${REDIS_URL:redis://localhost:6379}

Configuration

string

The URL of the Redis instance to use for distributed locking.

Trigger Type

This Module adds a new Trigger Type: cron.

Show Trigger Config

string

required

Standard cron expression defining the schedule. Supports the following format:

* * * * * *
│ │ │ │ │ │
│ │ │ │ │ └─── Day of week (0–6, Sun=0)
│ │ │ │ └───── Month (1–12)
│ │ │ └─────── Day of month (1–31)
│ │ └───────── Hour (0–23)
│ └─────────── Minute (0–59)
└─────────── Second (0–59)

string

Function ID for conditional execution. The engine invokes it with the cron event; if it returns false, the handler function is not called.

Show Trigger Event Payload

The following fields are passed to the handler function (and to condition_function_id if set) each time the trigger fires.

string

Always "cron".

string

The ID of the cron trigger that fired.

string

The time the job was scheduled to run, in RFC 3339 format.

string

The actual time the job began executing, in RFC 3339 format.

Sample Code

TypeScript
Python
Rust

const fn = iii.registerFunction(
  { id: 'jobs::cleanupOldData' },
  async (event) => {
    console.log('Running cleanup scheduled at:', event.scheduled_time)
    return {}
  },
)

iii.registerTrigger({
  type: 'cron',
  function_id: fn.id,
  config: { expression: '0 0 2 * * *' },
})

def cleanup_old_data(event):
    print('Running cleanup scheduled at:', event['scheduled_time'])
    return {}

iii.register_function({'id': 'jobs::cleanupOldData'}, cleanup_old_data)
iii.register_trigger({'type': 'cron', 'function_id': 'jobs::cleanupOldData', 'config': {'expression': '0 0 2 * * *'}})

iii.register_function(
    RegisterFunctionMessage::with_id("jobs::cleanupOldData".into()),
    |event: Value| async move {
        println!("Running cleanup scheduled at: {}", event["scheduled_time"]);
        Ok(json!({}))
    },
);

iii.register_trigger(RegisterTriggerInput {
    trigger_type: "cron".into(),
    function_id: "jobs::cleanupOldData".into(),
    config: json!({ "expression": "0 0 2 * * *" }),
})?;

Common Cron Expressions

Expression	Description
`0 * * * * *`	Every minute
`0 0 * * * *`	Every hour
`0 0 0 * * *`	Every day at midnight
`0 0 0 * * 0`	Every Sunday at midnight
`0 0 2 * * *`	Every day at 2 AM
`0 /5 * * *`	Every 5 minutes
`0 0 9-17 * * 1-5`	Every hour from 9 AM to 5 PM, Monday to Friday

Distributed Execution

When running multiple iii Engine instances, the Cron Module uses distributed locking to ensure jobs execute only once:

Getting Started

Primitives & Concepts

How-to Guides

Modules

Console

Advanced

Examples

Sample Configuration

Configuration

Adapters

modules::cron::KvCronAdapter

Configuration

modules::cron::RedisCronAdapter

Configuration

Trigger Type

Sample Code

Common Cron Expressions

Distributed Execution

​Sample Configuration

​Configuration

​Adapters

​modules::cron::KvCronAdapter

​Configuration

​modules::cron::RedisCronAdapter

​Configuration

​Trigger Type

​Sample Code

​Common Cron Expressions

​Distributed Execution

Sample Configuration

Configuration

Adapters

modules::cron::KvCronAdapter

Configuration

modules::cron::RedisCronAdapter

Configuration

Trigger Type

Sample Code

Common Cron Expressions

Distributed Execution