litellm [Bug]: /file Unable to use files_settings with Azure config unless env vars are explicitly set

What happened?

Hi team,

We’re encountering an issue when using files_settings in the config file to define a custom Azure provider. Here's the configuration we’re using:

files_settings:
  - custom_llm_provider: azure
    api_base: https://resource.openai.azure.com
    api_key: os.environ/MY_KEY
    api_version: "my_version"

Despite providing api_base, api_key, and api_version in the config, we receive the below error.

It seems like litellm still expects env vars listed in proxy_server_config.yaml even though the config file explicitly defines everything.

Relevant log output

{
  "error": {
    "message": "Must provide one of the `base_url` or `azure_endpoint` arguments, or the `AZURE_OPENAI_ENDPOINT` environment variable",
    "type": "None",
    "param": "None",
    "code": "500"
  }
}