Skip to navigation
FabricAgents

Use Codex with Fabric AI Gateway

You can send OpenAI Codex traffic through Fabric AI Gateway by adding the gateway as a model provider in Codex’s config.toml file and passing a gateway key as a custom header. The gateway then applies your plugins to Codex requests, and you can review them in the console. This topic shows you how to configure Codex and confirm that requests arrive.

Prerequisites

Before you begin, make sure you have the following:

Configure Codex to use the gateway

Codex reads its settings from ~/.codex/config.toml. To configure Codex, do the following:

  1. In the Fabric console, select LLMs > Routes, find your OpenAI route, and then select Copy LLM base URL.

  2. Set your gateway key in an environment variable, for example in your shell profile:

    export FABRIC_GATEWAY_KEY="GATEWAY_KEY"

  3. Open ~/.codex/config.toml, and add the gateway as a model provider:

    model_provider = "fabric"
    [model_providers.fabric]
    name = "Fabric AI Gateway"
    base_url = "BASE_URL"
    wire_api = "responses"
    env_http_headers = { "fg-api-key" = "FABRIC_GATEWAY_KEY" }

  4. Replace GATEWAY_KEY with your gateway key and BASE_URL with the URL that you copied, ending in /v1.

  5. Restart Codex.

The settings do the following:

  • model_provider makes Codex use the provider that you define.
  • base_url sends requests to the gateway route instead of the OpenAI API.
  • wire_api = "responses" makes Codex use the OpenAI Responses API format.
  • env_http_headers adds the gateway key to each request, using the value of the FABRIC_GATEWAY_KEY environment variable. This keeps the key out of the file.

Treat the gateway key as a secret. Don’t put it in a config file that you commit.

The gateway supplies the OpenAI credential. It adds the API key saved on the connection when it forwards requests to OpenAI, so Codex doesn’t need an OpenAI key. Use a model that the connection allows.

Confirm that requests pass through the gateway

To confirm that Codex uses the gateway, do the following:

  1. In Codex, send a message, for example Hello, is this working?.
  2. In the Fabric console, select Admin, and then select Traces.
  3. Find the requests from your user on the route.

Next steps