AI Response Transformer

The AI Response Transformer plugin uses a configured LLM service to transform the upstream’s HTTP(S) response before returning it to the client. It can also terminate or otherwise nullify the response if it fails a compliance or formatting check from the configured LLM service, for example.

This plugin supports llm/v1/chat requests for the same providers as the AI Proxy plugin.

It also uses the same configuration and tuning parameters as the AI Proxy plugin, in the config.llm block.

The AI Response Transformer plugin runs after the AI Proxy plugin, and after proxying to the upstream service, allowing it to also transform responses coming from a different LLM.

 
sequenceDiagram
    autonumber
    participant client as Client
    participant kong as Kong Gateway
    participant ai as AI LLM service
    participant backend as Backend service
    activate client
    activate kong
    client->>kong: Sends a request
    deactivate client
    activate ai
    kong->>ai: Sends client's request for transformation
    ai->>kong: Transforms request
    deactivate ai
    activate backend
    kong->>backend: Sends transformed request to backend
    backend->>kong: Returns response to Kong Gateway
    deactivate backend
    activate ai
    kong->>ai: Sends response to AI service
    ai->>kong: Transforms response
    deactivate ai
    activate client
    kong->>client: Returns transformed response to client
    deactivate kong
    deactivate client
  

Figure 1: The diagram shows the journey of a consumer’s request through Kong Gateway to the backend service, where it is transformed by both an AI LLM service and Kong’s AI Request Transformer and the AI Response Transformer plugins.

1. The Kong Gateway admin sets up an llm configuration block.
2. The Kong Gateway admin sets up a prompt. The prompt becomes the system message in the LLM chat request, and provides transformation instructions to the LLM for the returning upstream response body.
3. The client makes an HTTP(S) call.
4. After proxying the client’s request to the backend, Kong Gateway sets the entire response body as the user message in the LLM chat request, then sends it to the configured LLM service.
5. The LLM service returns a response assistant message, which is subsequently set as the upstream response body.
6. The plugin returns early (kong.response.exit) and can handle gzip or chunked requests, similar to the Forward Proxy plugin.

Adjusting response headers, status codes, and body

You can additionally instruct the LLM to respond in the following format, which lets you adjust the response headers, response status code, and response body:

{
  "headers":
    {
      "new-header": "new-value"
    }
}

If the parse_llm_response_json_instructions parameter is set to true, Kong Gateway will parse these instructions and set the specified response headers, response status code, and replacement response body. This lets you change specific headers such as Content-Type, or throw errors from the LLM.