AI Proxy - Custom upstream URL trigger "no host allowed while connecting to upstream"

[kdubuc]

Is there an existing issue for this?

• I have searched the existing issues

Kong version ($ kong version)

3.9

Current Behavior

When I want to setup AI proxy with a custom upstream url, I got an error

[lua] init.lua:1401:
balancer(): failed to set the current peer (address: api.scaleway.ai port: 443)
no host allowed while connecting to upstream
client: 172.17.0.1
server: kong
request: "POST /ai-proxy HTTP/1.1"
subrequest: "/kong_buffered_http"
host: "localhost:7110"
request_id: "58bd14166a68303a88699c54ea97ec62"

Expected Behavior

Kond should be running, and ready to proxy request to AI model

Steps To Reproduce

1- Setup kong like this

_format_version: "3.0"
services:
- url: http://0.0.0.0:8000
  plugins:
  - name: ai-proxy
    config:
      route_type: "llm/v1/chat"
      auth:
        header_name: Authorization
        header_value: "Bearer xxxxxx"
      model:
        provider: mistral
        name: mistral-nemo-instruct-2407
        options:
          mistral_format: openai
          upstream_url: "https://api.scaleway.ai/v1"
          max_tokens: 512
          temperature: 0.3
          top_p: 1.0

2- Launch kong

Anything else?

Bug possibly related : #12201, #14244

[kdubuc]

Update : DNS resolution is ok only if the service upstream url is equals to the model upstream url :

_format_version: "3.0"
services:
- - url: http://0.0.0.0:8000
+ - url: https://api.scaleway.ai
  plugins:
  - name: ai-proxy
    config:
      route_type: "llm/v1/chat"
      auth:
        header_name: Authorization
        header_value: "Bearer xxxxxx"
      model:
        provider: mistral
        name: mistral-nemo-instruct-2407
        options:
          mistral_format: openai
          upstream_url: "https://api.scaleway.ai/v1"
          max_tokens: 512
          temperature: 0.3
          top_p: 1.0

But the docs says :

Each of these AI-enabled routes must point to a null service. This service doesn’t need to map to any real upstream URL, it can point somewhere empty (for example, http://localhost:32000), because the AI Proxy plugin overwrites the upstream URL. This requirement will be removed in a later Kong revision.

https://docs.konghq.com/hub/kong-inc/ai-proxy/how-to/llm-provider-integration-guides/mistral/