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Using Codex with BlaBlador

This guide explains how to configure the Codex CLI harness to work with BlaBlador's API, giving you access to open-source models like Qwen3.5-35B-A3B through the VS Code extension.

Prerequisites

Step 0: Install Codex Extension in VS Code

  1. Open VS Code
  2. Press Ctrl+Shift+X (or Cmd+Shift+X on macOS) to open Extensions
  3. Search for "codex" or "openai"
  4. Look for the Codex extension (by OpenAI)
  5. Click Install

Verify Installation

After installation: 1. Reload VS Code (Ctrl+Shift+P → "Developer: Reload Window") 2. You should see Codex-related commands available via Ctrl+Shift+P

Step 1: Set Up Your API Key

Create an .env file in ~/.codex with your BlaBlador API key:

echo 'LOCAL_LLM_API_KEY="YOUR_BLABLADOR_API_KEY"' > ~/.codex/.env

Set appropriate permissions for security:

chmod 600 ~/.codex/.env

Step 2: Configure Codex

Create or edit ~/.codex/config.toml with the following configuration:

model = "alias-code"
model_provider = "blablador"

[model_providers.blablador]
name = "BlaBlador"
base_url = "https://api.blablador.fz-juelich.de/v1"
env_key = "LOCAL_LLM_API_KEY"
wire_api = "responses"

Configuration Explanation

  • model = "alias-code": Uses the Qwen3.5-35B-A3B model via the alias
  • model_provider = "blablador": Specifies the BlaBlador provider
  • base_url: The BlaBlador API endpoint
  • env_key: The environment variable containing your API key
  • wire_api = "responses": Uses the Responses API compatible mode

Step 3: Use in VS Code

  1. Press Ctrl+Shift+P (or Cmd+Shift+P on macOS)
  2. Type "Reload Window" and select "Developer: Reload Window"
  3. The Codex extension should now be ready to use with BlaBlador models

Available Models

BlaBlador hosts multiple open-source models. To see available models, visit the BlaBlador models page or check the API directly:

curl -H "Authorization: Bearer $LOCAL_LLM_API_KEY" https://api.blablador.fz-juelich.de/v1/models

Troubleshooting

Error: "API key not found"

Make sure your .env file is at ~/.codex/.env and contains LOCAL_LLM_API_KEY="YOUR_KEY".

Error: "Connection refused"

Verify that: 1. Your API key is valid and not expired 2. You have internet access 3. The BlaBlador service is available at https://api.blablador.fz-juelich.de

Error: "Model not found"

Check that the model name is correct and available on BlaBlador. Use the alias alias-code for Qwen3.5-35B-A3B or specify the full model path.

Codex Extension Not Showing Up

  1. Ensure the extension is installed and enabled
  2. Reload VS Code window
  3. Check if codex CLI is installed: which codex
  4. Verify config at ~/.codex/config.toml is valid TOML

See Also