FastMCP working

Author: danlapid

.gitignore

@@ -1,4 +1,5 @@
 .venv/
 node_modules/
 src/vendor/
-.vscode/
+.vscode/
+.wrangler/

README.md

@@ -1,19 +1,13 @@
-# Vendoring Packages: FastAPI + Jinja2 Example
+# Python Workers: FastMCP Example
 
-*Note: You must have Python Packages enabled on your account for built-in packages to work. Request Access to our Closed Beta using [This Form](https://forms.gle/FcjjhV3YtPyjRPaL8)*
-
-This is an example of a Python Worker that uses a built-in package (FastAPI) with a vendored package (Jinja2).
+This is an example of a Python Worker that uses the FastMCP package.
 
 ## Adding Packages
 
-Built-in packages can be selected from [this list](https://developers.cloudflare.com/workers/languages/python/packages/#supported-packages) and added to your `requirements.txt` file. These can be used with no other explicit install step.
-
 Vendored packages are added to your source files and need to be installed in a special manner. The Python Workers team plans to make this process automatic in the future, but for now, manual steps need to be taken.
 
 ### Vendoring Packages
 
-[//]: # (NOTE: when updating the instructions below, be sure to also update the vendoring.yml CI workflow)
-
 First, install Python3.12 and pip for Python 3.12.
 
 *Currently, other versions of Python will not work - use 3.12!*
@@ -30,34 +24,11 @@ Within our virtual environment, install the pyodide CLI:
 .venv/bin/pyodide venv .venv-pyodide
 ```
 
-Next, add packages to your vendor.txt file. Here we'll add jinja2
-```
-jinja2
-```
-
-Lastly, add these packages to your source files at `src/vendor`. For any additional packages, re-run this command.
+Lastly, download the vendored packages. For any additional packages, re-run this command.
 ```console
 .venv-pyodide/bin/pip install -t src/vendor -r vendor.txt
 ```
 
-### Using Vendored packages
-
-In your wrangler.toml, make the vendor directory available:
-
-```toml
-[[rules]]
-globs = ["vendor/**"]
-type = "Data"
-fallthrough = true
-```
-
-Now, you can import and use the packages:
-
-```python
-import jinja2
-# ... etc ...
-```
-
 ### Developing and Deploying
 
 To develop your Worker, run `npx wrangler@latest dev`.

src/asgi.py

@@ -1,159 +1,6 @@
 from asyncio import Future, Event, Queue, ensure_future, sleep, create_task
 from contextlib import contextmanager
 from inspect import isawaitable
-import typing
-
-if typing.TYPE_CHECKING:
-    from typing import (
-        Any,
-        Callable,
-        Literal,
-        Optional,
-        Protocol,
-        TypedDict,
-        Union,
-        NotRequired,
-    )
-    from collections.abc import Awaitable, Iterable, MutableMapping
-
-    class HTTPRequestEvent(TypedDict):
-        type: Literal["http.request"]
-        body: bytes
-        more_body: bool
-
-    class HTTPResponseDebugEvent(TypedDict):
-        type: Literal["http.response.debug"]
-        info: dict[str, object]
-
-    class HTTPResponseStartEvent(TypedDict):
-        type: Literal["http.response.start"]
-        status: int
-        headers: NotRequired[Iterable[tuple[bytes, bytes]]]
-        trailers: NotRequired[bool]
-
-    class HTTPResponseBodyEvent(TypedDict):
-        type: Literal["http.response.body"]
-        body: bytes
-        more_body: NotRequired[bool]
-
-    class HTTPResponseTrailersEvent(TypedDict):
-        type: Literal["http.response.trailers"]
-        headers: Iterable[tuple[bytes, bytes]]
-        more_trailers: bool
-
-    class HTTPServerPushEvent(TypedDict):
-        type: Literal["http.response.push"]
-        path: str
-        headers: Iterable[tuple[bytes, bytes]]
-
-    class HTTPDisconnectEvent(TypedDict):
-        type: Literal["http.disconnect"]
-
-    class WebSocketConnectEvent(TypedDict):
-        type: Literal["websocket.connect"]
-
-    class WebSocketAcceptEvent(TypedDict):
-        type: Literal["websocket.accept"]
-        subprotocol: NotRequired[str | None]
-        headers: NotRequired[Iterable[tuple[bytes, bytes]]]
-
-    class _WebSocketReceiveEventBytes(TypedDict):
-        type: Literal["websocket.receive"]
-        bytes: bytes
-        text: NotRequired[None]
-
-    class _WebSocketReceiveEventText(TypedDict):
-        type: Literal["websocket.receive"]
-        bytes: NotRequired[None]
-        text: str
-
-    WebSocketReceiveEvent = Union[
-        _WebSocketReceiveEventBytes, _WebSocketReceiveEventText
-    ]
-
-    class _WebSocketSendEventBytes(TypedDict):
-        type: Literal["websocket.send"]
-        bytes: bytes
-        text: NotRequired[None]
-
-    class _WebSocketSendEventText(TypedDict):
-        type: Literal["websocket.send"]
-        bytes: NotRequired[None]
-        text: str
-
-    WebSocketSendEvent = Union[_WebSocketSendEventBytes, _WebSocketSendEventText]
-
-    class WebSocketResponseStartEvent(TypedDict):
-        type: Literal["websocket.http.response.start"]
-        status: int
-        headers: Iterable[tuple[bytes, bytes]]
-
-    class WebSocketResponseBodyEvent(TypedDict):
-        type: Literal["websocket.http.response.body"]
-        body: bytes
-        more_body: NotRequired[bool]
-
-    class WebSocketDisconnectEvent(TypedDict):
-        type: Literal["websocket.disconnect"]
-        code: int
-        reason: NotRequired[str | None]
-
-    class WebSocketCloseEvent(TypedDict):
-        type: Literal["websocket.close"]
-        code: NotRequired[int]
-        reason: NotRequired[str | None]
-
-    class LifespanStartupEvent(TypedDict):
-        type: Literal["lifespan.startup"]
-
-    class LifespanShutdownEvent(TypedDict):
-        type: Literal["lifespan.shutdown"]
-
-    class LifespanStartupCompleteEvent(TypedDict):
-        type: Literal["lifespan.startup.complete"]
-
-    class LifespanStartupFailedEvent(TypedDict):
-        type: Literal["lifespan.startup.failed"]
-        message: str
-
-    class LifespanShutdownCompleteEvent(TypedDict):
-        type: Literal["lifespan.shutdown.complete"]
-
-    class LifespanShutdownFailedEvent(TypedDict):
-        type: Literal["lifespan.shutdown.failed"]
-        message: str
-
-    WebSocketEvent = Union[
-        WebSocketReceiveEvent, WebSocketDisconnectEvent, WebSocketConnectEvent
-    ]
-
-    ASGIReceiveEvent = Union[
-        HTTPRequestEvent,
-        HTTPDisconnectEvent,
-        WebSocketConnectEvent,
-        WebSocketReceiveEvent,
-        WebSocketDisconnectEvent,
-        LifespanStartupEvent,
-        LifespanShutdownEvent,
-    ]
-
-    ASGISendEvent = Union[
-        HTTPResponseStartEvent,
-        HTTPResponseBodyEvent,
-        HTTPResponseTrailersEvent,
-        HTTPServerPushEvent,
-        HTTPDisconnectEvent,
-        WebSocketAcceptEvent,
-        WebSocketSendEvent,
-        WebSocketResponseStartEvent,
-        WebSocketResponseBodyEvent,
-        WebSocketCloseEvent,
-        LifespanStartupCompleteEvent,
-        LifespanStartupFailedEvent,
-        LifespanShutdownCompleteEvent,
-        LifespanShutdownFailedEvent,
-    ]
-
 
 ASGI = {"spec_version": "2.0", "version": "3.0"}
 
@@ -274,14 +121,12 @@ async def process_request(app, req, env):
     await receive_queue.put({"body": b"", "more_body": False, "type": "http.request"})
 
     async def receive():
-        print("Receiving")
         message = None
         if not receive_queue.empty():
             message = await receive_queue.get()
         else:
             await finished_response.wait()
             message = {"type": "http.disconnect"}
-        print(f"Received {message}")
         return message
 
     # Create a transform stream for handling streaming responses
@@ -290,12 +135,11 @@ async def receive():
     writable = transform_stream.writable
     writer = writable.getWriter()
 
-    async def send(got: "ASGISendEvent"):
+    async def send(got):
         nonlocal status
         nonlocal headers
         nonlocal is_sse
 
-        print(got)
         if got["type"] == "http.response.start":
             status = got["status"]
             # Like above, we need to convert byte-pairs into string explicitly.
@@ -305,7 +149,6 @@ async def send(got: "ASGISendEvent"):
                 if k.lower() == "content-type" and v.lower().startswith(
                     "text/event-stream"
                 ):
-                    print("SSE RESPONSE")
                     is_sse = True
 
                     # For SSE, create and return the response immediately after http.response.start
@@ -318,7 +161,6 @@ async def send(got: "ASGISendEvent"):
         elif got["type"] == "http.response.body":
             body = got["body"]
             more_body = got.get("more_body", False)
-            print(f"{body=}, {more_body=}")
 
             # Convert body to JS buffer
             px = create_proxy(body)
@@ -367,7 +209,6 @@ async def run_app():
     # For non-SSE responses, we need to wait for the application to complete
     if not is_sse:
         await app_task
-    print(f"Returning response! {is_sse}")
     return response
 
 

src/uvicorn.py

@@ -0,0 +1,5 @@
+# This file must exist as a hack to satisfy mcp.
+# mcp has an optional dependency on uvicorn but still imports it at the top scope, see:
+# https://github.com/modelcontextprotocol/python-sdk/blob/main/src/mcp/server/fastmcp/server.py#L18
+# Because we never call `run_sse_async` this is not required. However, Python workers used asgi.py
+# rather than uvicorn which is why this hack is needed. With this, the import succeeds.