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This tutorial does not cover how to expose your Tracecat instance to the public internet.
  • If you’re running Tracecat locally, you’ll need use a tunneling service like ngrok to receive webhook requests from the public internet.
  • If you’re running Tracecat on AWS Fargate, Tracecat is automatically exposed to the public internet via an Application Load Balancer.

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What you’ll learn

By the end of this tutorial, you’ll learn how to create two types of workflows:
  • A webhook workflow that receives a JSON string and decodes it using the FN.deserialize_json function.
  • A scheduled workflow that sends a notification to a Slack channel at a regular interval.

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Trigger action

Every Tracecat workflow comes with a single Trigger action. This trigger action cannot be deleted. Click on the Trigger action to activate the webhooks and schedules configuration panel. Trigger action

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Webhooks

Webhook URLs are secrets and should not be exposed in public. The webhook URL shown in the UI screenshots are for demonstration only.
Webhooks are disabled by default. To activate a workflow’s webhook, click on the Trigger action, then toggle the webhook on. Events can then be triggered by making a POST request to the webhook URL. Webhook URLs are formatted as: 
WEBHOOK_URL=https://<tracecat-public-url>/api/webhooks/<workflow-id>/<webhook-secret>

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Authenticate webhook requests with API keys

You can lock down a webhook by requiring callers to present an API key.
  1. Open the Trigger action panel and locate the API Key section.
  2. Click Generate API key. Copy the value when prompted—it is only displayed once.
  3. Add the following header to every webhook request: 
    x-tracecat-api-key: <your-api-key>
If a request omits the header or uses a revoked key, Tracecat rejects it with an HTTP 401 Unauthorized response. You can rotate the key at any time, or revoke it to temporarily block requests without deleting the configuration.

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Restrict webhook sources with IP allowlists

Use IP allowlists to accept requests only from trusted networks.
  1. In the Trigger panel, add one or more IPv4 addresses or CIDR ranges (e.g. 203.0.113.7 or 203.0.113.0/24) to the IP Allowlist field.
  2. Click Save to apply the changes.
Tracecat compares the requester’s IP address against the allowlist. Requests without a client IP or originating from outside the configured ranges are rejected with an HTTP 403 Forbidden response. Leave the list empty to allow traffic from any source.

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Schedules

Schedules are disabled by default. To activate a workflow’s schedule, click on the Trigger action, then toggle the schedule on. Schedule action From here you can enter a recurring schedule with a timeout and offset. Tracecat defaults to using UTC time, so it’s convenient to use offset to work with timezone differences. For example, if you are in America/New_York timezone and want to run a workflow every day at 9AM, you can configure the schedule to run every 1 day with an offset of PT13H. This is because 00:00 UTC is 8PM EDT. Schedule modal

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Webhook verification

Some tools (e.g. Slack, Okta) that send webhooks require a specific response after the webhook payload is received. This is used to verify that the webhook was received and processed by Tracecat. To echo the webhook payload back to the server, add the query parameter echo=true to the webhook URL. 
https://${WEBHOOK_URL}?echo=true
By default, we return the workflow context (e.g. execution_id) as the response to the webhook POST request. To return an empty response with status code 200, set the query parameter empty_echo=true. 
https://${WEBHOOK_URL}?empty_echo=true

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Allowed webhook methods

By default, only POST requests are allowed. To allow other methods, select the trigger action then configure POST and / or GET in the Allowed HTTP Methods section of the action panel.

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Vendor-specific webhooks

Can’t find the vendor you’re looking for? Open an issue on GitHub and we’ll add support for it.
Some vendors have more complex webhook verification requirements. To support this, Tracecat supports vendor-specific webhook verification. 
https://${WEBHOOK_URL}?vendor=okta
Vendors currently supported:
  • okta: must allow GET requests for verification.

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Pause or delete schedule

You can pause or delete the schedule by selecting the schedule menu in the Trigger settings panel. Pause or delete schedule

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Reference webhook data

Use the ${{ TRIGGER }} expression context to reference data passed via webhooks. A child workflow also receives input data via ${{ TRIGGER }} context. Trigger expression Learn more in the child workflows and expressions docs.

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Webhook content types

Traceat’s webhook parser supports the following Content-Type headers:
  • application/json
  • application/x-ndjson
  • application/www-form-urlencoded
The webhook sender must set the Content-Type header to the appropriate value. If no Content-Type header is set, Tracecat defaults to application/json.

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Example: Elastic Security

To ingest alerts from Elastic Security, you’ll need to configure their webhook connector in Kibana to send NDJSON with the expected content type (application/x-ndjson).
1

Configure Elastic webhook rule action body

Configure the body of the webhook connector to return the alerts in NDJSON format:
{{#context.alerts}}
{{{.}}}
{{/context.alerts}}
2

Configure content type

The webhook request sent by Elastic Security must have the following header:
{
  "Content-Type": "application/x-ndjson",
}
3

Receive webhook in Tracecat

Tracecat looks at the Content-Type header to determine how to parse the webhook payload. In this case, we’re using application/x-ndjson, so Tracecat will parse the webhook payload as NDJSON.The ${{ TRIGGER }} expression context will return a list of deserialized JSON objects.Elastic Security webhook

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Parse webhook payload

1

Deserialize JSON action

Add the core.transform.reshape action to the workflow. Use the FN.deserialize_json function to decode an incoming JSON string via webhook.
value: ${{ FN.deserialize_json(TRIGGER.payload)}}
Deserialize JSON action
2

Save workflow

Save the workflow.
3

Toggle webhook

Click on the Trigger action. Enable the webhook by clicking on the toggle switch. The workflow will now receive webhook events.Toggle webhook
4

POST webhook request

Copy the webhook URL to your clipboard, then make a POST request to the webhook URL. For example, using curl:
curl -X POST \
  -H "Content-Type: application/json" \
  -d '{"payload": "{\"name\": \"John\", \"age\": 30}"}' \
  <webhook-url>
5

View workflow runs

Go to the Runs view and check that the workflow has run successfully. The workflow should have received the webhook payload and deserialized it into a JSON object.Deserialize JSON result