Async on NoRaincheck

Python MCP - Mounting to an Existing FastAPI ASGI Server

Tue, 01 Apr 2025 00:00:00 +0000

Python MCP - Mounting to an Existing FastAPI ASGI Server

April 2025

You can mount the SSE server to an existing FastAPI ASGI server dynamically. The way I’ve made it work is as follows:

 1sse = SseServerTransport(...)
 2
 3...
 4app.router.routes.append(Mount("/messages", app=sse.handle_post_message))
 5
 6@app.get("/sse")
 7async def handle_mcp_connection(request: Request):
 8 async with sse.connect(sse(request.scope, request.receive, request.send) as (
 9 read_stream,
10 write_stream,
11 ):
12 await mcp._mcp_server.run(
13 read_stream,
14 write_stream,
15 mcp._mcp_server.create_initialization_options(),
16 )

This seemed to work pretty well, along with having Redis as an intermediary broker for dealing with state.

Syncify Python Async Functions

Tue, 01 Apr 2025 00:00:00 +0000

Syncify Python Async Functions

April 2025

There’s a lot to unpack with Python shenanigans. Including why nest-asyncio even exists. Here is yet another pattern (note: you really should look into https://asyncer.tiangolo.com/ if it fits for you).

1def syncify(func, *args, **kwargs):
2 def wrapper(coro):
3 return asyncio.run(coro)
4
5 with ThreadPoolExecutor(max_workers=1) as executor:
6 result = next(executor.map(wrapper, [func(*args, **kwargs)]))
7 return result

Which delegates/moves the execution to a threadpool to bypass potential issues. This is definitely not a ‘performant’ option, but it may save your skin.

I’ll point out in general, where your event loop is not nested, you could just use asyncio.run.