Bug: Kibana Detection Rule With Terraform - Documents Field

Introduction

When working with Kibana and Terraform to automate security detection rule creation, you may encounter challenges, especially when configuring complex fields like documents. This article delves into a specific bug reported where setting the documents field as an object within a Kibana detection rule via Terraform is not functioning as expected. This issue highlights the discrepancies between the expected API structure and Terraform's handling of the documents field, impacting the automation of security rule deployment. Understanding this bug and its implications is crucial for anyone leveraging Terraform to manage Kibana security rules. This article will guide you through the details of the bug, its reproduction steps, and expected behavior, offering insights into how to navigate this challenge.

Understanding the Bug: Setting 'documents' Field in Kibana Detection Rule via Terraform

The core issue lies in the inability to properly configure the documents field within a Kibana security detection rule using Terraform. Terraform, in its current implementation, restricts the documents field in the actions.params block to be a string. However, the Kibana API anticipates this field to be an object or a list of objects. This mismatch causes a configuration conflict where the exported rule structure deviates from the intended format, thereby hindering the correct automation of rule creation. This discrepancy is not just a minor inconvenience; it represents a significant obstacle in automating security workflows within the Elastic Stack ecosystem. The expected behavior is that Terraform should seamlessly handle complex data structures like objects and lists for the documents field, aligning with the Kibana API's expectations. This capability is essential for efficiently managing and deploying sophisticated detection rules that require detailed document specifications. The bug underscores the importance of maintaining parity between infrastructure-as-code tools like Terraform and the APIs of the services they manage. A clear understanding of such limitations and workarounds is crucial for architects, DevOps engineers, and security professionals who rely on automation to maintain robust security postures. The implications extend beyond mere syntax; they touch upon the core principles of automation, where predictable and consistent behavior is paramount. Thus, addressing this bug is a key step in ensuring the reliability and efficiency of security automation pipelines.

How to Reproduce the Bug

To effectively demonstrate the bug where the documents field cannot be set as an object in a Kibana detection rule via Terraform, follow these steps. This will allow you to see the issue firsthand and understand its implications. Reproducing the bug involves setting up a minimal Terraform configuration that attempts to define a Kibana security detection rule with specific document parameters.

1. First, you need a basic Terraform configuration file (.tf) that defines an elasticstack_kibana_security_detection_rule resource. This resource will represent the Kibana detection rule you intend to create.

2. Within this configuration, specify the name and actions blocks. The actions block is where you define how the rule should respond when triggered. This involves setting parameters like id, action_type_id, and group.

3. The critical part is the params block inside actions. Here, you will attempt to set the documents field. Try setting it as either a string representation of an object or a string representation of a list of objects. Examples include:

   params = {
     documents = ["{'test':'test'}"] # or "[{'test':'test'}]"
   }
   

4. After configuring the Terraform file, run terraform apply or tofu apply. This command will instruct Terraform to apply the configuration and provision the resources defined.

5. Upon running the apply command, Terraform will attempt to create the Kibana detection rule. However, due to the bug, it will encounter an error. The error message typically indicates an incorrect attribute value type, specifically stating that a string is required for the documents field, but an object is being provided. This error confirms the bug.

By following these steps, you can clearly observe the bug in action, reinforcing the importance of understanding such limitations when automating Kibana security rules with Terraform. This hands-on approach provides a practical understanding of the issue and its impact on automation workflows.

Expected Behavior

The expected behavior when configuring a Kibana security detection rule with Terraform is that the documents field should seamlessly accept an object or a list of objects. This aligns with the structure anticipated by the Kibana API, which is designed to handle complex data types for action parameters. Instead of being constrained to a string representation, Terraform should allow the documents field to mirror the structure of action connectors, enabling the creation of valid and functional rules. The desired outcome is that when Terraform applies the configuration, it should translate the object or list of objects into the correct JSON structure for the Kibana API. For instance, if you define the documents field as a list containing a single object:

params = {
  documents = [
    {
      "test": "test"
    }
  ]
}

Terraform should create a rule in Kibana where the `