---
title: How to add a trigger to a function
description: Learn how to add triggers to your Serverless Functions in Scaleway.
tags: functions
dates:
  validation: 2025-10-27
  posted: 2023-04-27
---
import Requirements from '@macros/iam/requirements.mdx'


This page shows you how to configure triggers for your Serverless Functions. A trigger is an event that invokes a function.

In a serverless architecture, a function only runs when it is called by an event. A trigger is a mechanism that connects the function to an event source and enables the function to run automatically in response to specific events.

A trigger can be an HTTP request, a message from a queue or stream, a CRON schedule etc. It is configured during the function deployment, and determines how and when the function will run.

<Requirements />

- A Scaleway account logged into the [console](https://console.scaleway.com)
- [Owner](/iam/concepts/#owner) status or [IAM permissions](/iam/concepts/#permission) allowing you to perform actions in the intended Organization
- Created a [functions namespace](/serverless-functions/how-to/create-manage-delete-functions-namespace/)
- Created a [function](/serverless-functions/how-to/create-a-function/)
- [Created credentials](/queues/how-to/create-credentials/) for Scaleway Queues
- [Created a queue](/queues/how-to/create-manage-queues/)

<Message type="important">
You can create triggers on private functions, but to update the privacy of a function from **public** to **private**, you must recreate the existing **Queues** and **NATS** triggers after the privacy change. We are actively working to make this operation as seamless as possible.
</Message>

<Message type="note">
  Triggers send messages through a `POST` request with the message body in the request body.
</Message>

## Queue triggers

<Message type="note">
You must have at least the `MessagingAndQueuingReadOnly` permission in the Project containing the queue to add a queue trigger to Serverless Functions.

Refer to the [permissions sets documentation](/iam/reference-content/permission-sets/) for more information.
</Message>

[Queue triggers](/serverless-functions/concepts/#queue-trigger) allow you to automatically invoke a function using events stored in a [queue](/queues/concepts/#queue).

Only queues created with the Scaleway Queues product are compatible with Serverless Functions.

The configuration of the queue retention may affect the behavior of the trigger. Refer to the [Considerations to configure event retention for queue trigger inputs](/serverless-functions/reference-content/configure-trigger-inputs/) page for more information.

1. Click **Functions** in the **Serverless** section of the side menu. The functions page displays.
2. Click the relevant functions namespace.
3. Click the name of the function you want to manage. The function **Code** tab displays.
4. Click the **Triggers** tab. The trigger configuration displays.
5. Click **Create trigger**. The trigger creation form displays in a pop-up.
6. Enter a **name** for your trigger and select the **Queues (Scaleway)** type, then select your queue name.
7. Click **Create trigger** to launch trigger creation.

<Message type="note">
  **Retry Policy:** If the Function returns a status code superior or equal to 300, sending the message will be retried up to three times.
</Message>

## NATS triggers

<Message type="note">
You must have at least the `MessagingAndQueuingReadOnly` permission in the Project containing the NATS account to add to Serverless Functions.

Refer to the [permissions sets documentation](/iam/reference-content/permission-sets/) for more information.
</Message>


[NATS triggers](/serverless-functions/concepts/#nats-trigger) allow you to automatically invoke a function using messages sent in a [NATS](/nats/concepts/#nats-messaging-system) subject.

Scaleway [NATS subjects](/nats/quickstart/) are compatible with Serverless Functions.

1. Click **Functions** in the **Serverless** section of the side menu. The functions page displays.
2. Click the relevant functions namespace.
3. Click the name of the function you want to manage. The function **Code** tab displays.
4. Click the **Triggers** tab. The trigger configuration displays.
5. Click **Create trigger**. The trigger creation form displays in a pop-up.
6. Enter a **name** for your trigger and select the **NATS (Scaleway)** type, then select your NATS account and subject name.
7. Click **Create trigger** to launch trigger creation.

<Message type="note">
  **Retry Policy:** If the Function returns a status code superior or equal to 300, sending the message will be retried up to three times.
</Message>

## CRON triggers

[CRON triggers](/serverless-functions/concepts/#cron-trigger) allow you to invoke your functions based on a recurring schedule. The CRON triggers for Serverless Functions use the **UTC** time zone.

<Message type="note">
The arguments of a CRON trigger are injected in the body of the `POST` HTTP request, and sent to the `/` endpoint.
</Message>

1. Click **Functions** in the **Serverless** section of the side menu. The functions page displays.
2. Click the relevant functions namespace.
3. Click the name of the function you want to manage. The function **Code** tab displays.
4. Click the **Triggers** tab. The trigger configuration displays.
5. Click **Create trigger**. The trigger creation form displays in a pop-up.
6. Enter a **name** for your trigger and select the **CRON** type.
7. Enter the cron schedule in UNIX format (`* * * * *`) and paste your JSON arguments in the form.
8. Click **Create trigger** to launch trigger creation.

<Message type="note">
    Refer to the [cron schedules reference](/serverless-functions/reference-content/cron-schedules/) for more information.
</Message>