This repository demonstrates how to run the OpenAI Codex CLI inside a Docker container with your local Windows folder mounted for development. It uses an .env file to securely provide your API key and includes .gitignore and .dockerignore to keep secrets and unnecessary files out of version control.

C:\CodexApp
├── Dockerfile
├── docker-compose.yml
├── .env
├── .gitignore
└── .dockerignore

• Docker Desktop installed and running on Windows
• A valid OpenAI API key

In C:\CodexApp\.env, add:

OPENAI_API_KEY=sk-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Note:

• Never commit the .env file to Git.
• Rotate or revoke your key by updating this file.

# Ignore Node modules
node_modules/
# Ignore environment files
.env
# Ignore Docker Compose overrides
docker-compose.override.yml

# Exclude secrets and VCS from build context
.env
.git
node_modules

Create C:\CodexApp\Dockerfile with:

FROM node:22-slim
# Set working directory inside container
WORKDIR /usr/src/app
# Install the Codex CLI globally
RUN npm install -g @openai/codex
# Default to bash for interactive use
CMD ["bash"]

Create C:\CodexApp\docker-compose.yml:

version: "3.9"
services:
 codex:
 build: .
 volumes:
 - C:\\CodexApp:/usr/src/app # Mount local Windows folder
 working_dir: /usr/src/app
 env_file:
 - .env # Load OPENAI_API_KEY from .env
 tty: true # Keep the shell open for interaction

1. Open PowerShell and navigate to your project folder:

   cd C:\CodexApp

2. Build the Docker image:

   docker-compose build

3. Start an interactive shell session in the container:

   docker-compose run codex

   • You will be at /usr/src/app inside the container.
   • Try verifying your key:

     echo $OPENAI_API_KEY

   • Run Codex commands:

     codex "Explain what this script does"

4. Run one-off Codex commands without entering the shell:

   docker-compose run codex codex "Generate a Node.js HTTP server"

• Editing Locally: Any edits you make in C:\Working are immediately available inside the container.
• Safety: Secrets never get baked into the image or committed to Git.
• Extensibility: You can add other services (databases, caches) to the docker-compose.yml later.

Happy coding with OpenAI Codex in Docker!