How to use a webhook to trigger a flow.

What are Webhooks?

Webhooks are HTTP requests that are triggered by an event. These are useful for being able to tell another application to do something, such as starting the execution of a Flow inside of Kestra.

Using Webhooks in Kestra

You can use webhooks to trigger an execution of your flow in Kestra. To do this, we can make a trigger with the type io.kestra.core.models.triggers.types.Webhook.

Once we've done this, we can add a key property, which can be random as this will be used to trigger the webhook. In the example, the key is set to 1KERKzRQZSMtLdMdNI7Nkr which is what we put at the end of our webhook URL to trigger it.

id: webhook
namespace: io.kestra.demo.flows

description: |
  Example flow for a webhook trigger.

  This endpoint doesn't need any login / password and is secured by `key` that is different for every flow

  - id: out
    type: io.kestra.core.tasks.debugs.Return
    format: "{{ trigger | json }}"

  - id: webhook
    type: io.kestra.core.models.triggers.types.Webhook
    # the required key to start this flow - might be passed as a secret
    key: 1KERKzRQZSMtLdMdNI7Nkr

The format of the Webhook URL follows

https://{your_hostname}/api/v1/executions/webhook/{namespace}/{flow_id}/{key} where:

  • your_hostname is the domain or IP of your server, e.g.
  • namespace is io.kestra.demo.flows
  • flow_id is webhook
  • key is 1KERKzRQZSMtLdMdNI7Nkr

With this information, you can test your flow by running the following command in the terminal to trigger the flow:

curl http://localhost:8080/api/v1/executions/webhook/io.kestra.demo.flows/webhook/1KERKzRQZSMtLdMdNI7Nkr

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