# server.py
import os
from mcp.server.fastmcp import FastMCP
from starlette.middleware.base import BaseHTTPMiddleware
from starlette.requests import Request
from starlette.responses import JSONResponse
class BearerAuthMiddleware(BaseHTTPMiddleware):
"""Simple Bearer token authentication middleware for HTTP transport."""
async def dispatch(self, request: Request, call_next):
expected_token = os.getenv("MCP_AUTH_TOKEN")
# Skip auth if no token is configured
if not expected_token:
return await call_next(request)
auth_header = request.headers.get("Authorization")
if not auth_header or not auth_header.startswith("Bearer "):
return JSONResponse(
{"error": "Unauthorized", "message": "Bearer token required"},
status_code=401,
)
token = auth_header[7:] # Remove "Bearer " prefix
if token != expected_token:
return JSONResponse(
{"error": "Forbidden", "message": "Invalid token"},
status_code=403,
)
return await call_next(request)
# This is the shared MCP server instance
mcp = FastMCP("eraser_mcp_server")
