How to configure ACL to allow specific Consumers and customize error responses in Kong?

[s35241607]

Hi,
I’m currently using Kong Gateway (Community Edition) and have the following requirements:

1. I want to use the ACL plugin to restrict access so that only specific Consumers (based on their API keys) can access my services.
2. If a Consumer is denied access due to ACL restrictions, I want Kong to return a JSON-formatted error response instead of the default plain text, e.g.:

   {
       "message": "Access denied",
       "status": 403,
       "request_id": "c0b9bc7692e1a95ae7ae545fe9e7a34c"
   }

Here’s what I’ve tried so far:

• Enabled the Key Authentication plugin to validate API keys.
• Configured the ACL plugin with a whitelist for the allowed group of Consumers.

The ACL restriction works, but the default error response is plain text:

Unauthorized
request_id: c0b9bc7692e1a95ae7ae545fe9e7a34c

Is there a way to:

1. Customize the error message to JSON format?
2. Achieve this without modifying Kong’s core or requiring Enterprise features?

Any guidance or examples would be much appreciated. Thanks!