MCP Auth Example

This project demonstrates a FastMCP server with both authenticated and unauthenticated endpoints. Bearer token authentication is enforced at the Nginx proxy layer. Envoy acts as a reverse proxy, forwarding requests to the MCP server and integrating with Open Policy Agent (OPA) for fine-grained authorization decisions. The repository includes example clients and a Docker setup for running all components together.

Features

• FastMCP server with and without authentication

• Example Python clients for both endpoints

• Docker Compose setup with Nginx, Envoy, and OPA integration

Project Structure

.
├── Dockerfile              # Dockerfile for MCP server
├── README.md
├── client.py               # Example client for both endpoints
├── docker-compose.yml      # Docker Compose setup (Nginx, Envoy, OPA, MCP)
├── proxy
│   ├── envoy               # Envoy config
│   │   ├── Dockerfile
│   │   ├── entrypoint.sh
│   │   └── envoy.yaml
│   ├── nginx.conf          # Nginx config for Bearer auth
│   └── policy.rego         # OPA policy for Envoy
├── pyproject.toml          # Python project config
├── server.py               # Unauthenticated MCP server (port 8000)
└── uv.lock

Quick Start

1. Install Dependencies

Install Python dependencies (requires uv):

uv sync

2. Build and Start Services

Build and start all services using Docker Compose:

docker compose up --build -d

• MCP server (unauthenticated): http://localhost:8000/mcp/

• MCP server (authenticated, via Nginx): http://localhost/mcp/

3. Test the Clients

Unauthenticated

uv run client.py

Authenticated

Edit client.py to use the authenticated endpoint and provide a valid token.

How It Works

• server.py: Runs a FastMCP server on port 8000 (no auth).

• client.py: Example client for both endpoints, supports custom authentication.

• proxy/: Contains Nginx and Envoy configs for authentication and policy enforcement.

Requirements

• fastmcp

• Docker & Docker Compose

• uv (for Python dependency management)