Scheduled Tasks with Cron

This guide explains how to schedule Lambda function execution using EventBridge Rules. The Cron component allows you to run functions on a recurring schedule using rate or cron expressions.

Creating a scheduled task

The simplest way to create a scheduled task is to provide a name, schedule expression, and handler:


from stelvio.aws.cron import Cron

# Run every hour
Cron("hourly-cleanup", "rate(1 hour)", "tasks/cleanup.handler")

# Run at 2 AM UTC daily
Cron("nightly-report", "cron(0 2 * * ? *)", "tasks/report.handler")

Schedule expressions

Stelvio supports two types of schedule expressions:

Rate expressions

Use rate expressions for simple recurring schedules:


Cron("every-minute", "rate(1 minute)", "tasks/ping.handler")
Cron("every-5-minutes", "rate(5 minutes)", "tasks/check.handler")
Cron("hourly", "rate(1 hour)", "tasks/sync.handler")
Cron("daily", "rate(1 day)", "tasks/report.handler")

Rate expression format: rate(value unit)

value: A positive number
unit: minute, minutes, hour, hours, day, or days

Note

Use singular form (minute, hour, day) when value is 1, plural otherwise.

Cron expressions

Use cron expressions for more complex schedules:


# Every day at 9:30 AM UTC
Cron("morning-report", "cron(30 9 * * ? *)", "tasks/report.handler")

# Every Monday at 8 AM UTC
Cron("weekly-digest", "cron(0 8 ? * MON *)", "tasks/digest.handler")

# First day of each month at midnight
Cron("monthly-cleanup", "cron(0 0 1 * ? *)", "tasks/cleanup.handler")

Cron expression format: cron(minutes hours day-of-month month day-of-week year)

Field	Values	Wildcards
Minutes	0-59	, - * /
Hours	0-23	, - * /
Day-of-month	1-31	, - * ? / L W
Month	1-12 or JAN-DEC	, - * /
Day-of-week	1-7 or SUN-SAT	, - * ? L #
Year	1970-2199	, - * /

Warning

All cron schedules run in UTC. Plan accordingly for your timezone.

Function configuration

Handler with options

Pass function options alongside the handler:


Cron("heavy-task",
    "rate(1 hour)",
    "tasks/process.handler",
    memory=1024,
    timeout=300
)

Using FunctionConfig

For complete control, use FunctionConfig:


from stelvio.aws.function import FunctionConfig

config = FunctionConfig(
    handler="tasks/process.handler",
    memory=2048,
    timeout=600,
    environment={"BATCH_SIZE": "1000"}
)

Cron("batch-job", "rate(6 hours)", config)

Using an existing Function

Reuse a Function across multiple cron jobs:


from stelvio.aws.function import Function

processor = Function("data-processor",
    handler="tasks/process.handler",
    memory=2048
)

# Different schedules, same function
Cron("hourly-process", "rate(1 hour)", processor)
Cron("daily-full-process", "rate(1 day)", processor)

Options

Disabling a schedule

Create a schedule in disabled state:


Cron("maintenance-job",
    "rate(1 hour)",
    "tasks/maintenance.handler",
    enabled=False
)

Custom payload

Pass a custom JSON payload to the Lambda function:


Cron("batch-job",
    "rate(1 hour)",
    "tasks/batch.handler",
    payload={"mode": "incremental", "batch_size": 100}
)

# Full sync on weekends
Cron("weekend-sync",
    "cron(0 0 ? * SAT *)",
    "tasks/batch.handler",
    payload={"mode": "full"}
)

The payload is passed as the event to your Lambda handler:


def handler(event, context):
    mode = event.get("mode", "incremental")
    batch_size = event.get("batch_size", 50)
    # Process based on payload

Linking resources

Connect your scheduled function to other resources using links:


from stelvio.aws.cron import Cron
from stelvio.aws.dynamo_db import DynamoTable

orders_table = DynamoTable(
    name="orders",
    fields={"order_id": "string", "status": "string"},
    partition_key="order_id"
)

Cron("process-orders",
    "rate(5 minutes)",
    "tasks/orders.handler",
    links=[orders_table]
)

AWS resources created

For each Cron component, Stelvio creates:

EventBridge Rule: The schedule trigger
EventBridge Target: Links the rule to the Lambda function
Lambda Permission: Allows EventBridge to invoke the function
Lambda Function: If not using an existing Function

Common patterns

Cleanup job


Cron("cleanup-old-data",
    "rate(1 day)",
    "tasks/cleanup.handler",
    payload={"retention_days": 30},
    timeout=900
)

Health check


Cron("health-check",
    "rate(5 minutes)",
    "tasks/health.handler",
    timeout=30
)

Report generation


Cron("daily-report",
    "cron(0 6 * * ? *)",  # 6 AM UTC daily
    "tasks/report.handler",
    memory=1024,
    timeout=300,
    payload={"report_type": "daily"}
)

Customization

The Cron component supports the customize parameter to override underlying Pulumi resource properties. For an overview of how customization works, see the Customization guide.

Resource Keys

Resource Key	Pulumi Args Type	Description
`rule`	EventRuleArgs	The EventBridge rule with schedule
`target`	EventTargetArgs	The target linking rule to Lambda
`permission`	PermissionArgs	Lambda permission for EventBridge
`function`	Nested (see Function customization)	The Lambda function

Example


cron = Cron(
    "my-cron",
    "rate(1 hour)",
    "functions/cleanup.handler",
    customize={
        "rule": {
            "tags": {"Schedule": "hourly"},
        }
    }
)