fastmcp-stdio-proxy

Purpose

Routing tools via FastMCP requires a persistent stdio connection. Running an MCP application in a detached Docker container causes an immediate exit because it hits an EOF on standard input. Furthermore, an MCP router container needs a way to invoke other MCP containers via stdio locally without exposing network layers.

Usage

1. Keeping FastMCP Alive in Docker Detached Mode

When using docker-compose up -d, add stdin_open and tty to the service definition. This tricks FastMCP's stdio listener into staying alive in the background:

services:
  mcp-router:
    build: .
    stdin_open: true
    tty: true