reload doesn't work from programmatic launch (asyncio)

[SamuelMarks]

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Description

reload doesn't work

Example Code

Given something simple like:

async def serve(reload=True):
    reload_dirs = [path.dirname(__file__)] if reload else None
    config = uvicorn.Config(
        "main:app",
        log_level="info",
        port=4000,
        reload=reload,
        reload_dirs=reload_dirs,
        reload_includes=reload_dirs,
    )
    server = uvicorn.Server(config)
    await server.serve()


if __name__ == "__main__":
    asyncio.run(serve())

Output looks good, but it never reloads, e.g., when I change a route's return value:

INFO:     Will watch for changes in these directories: ['/tmp/myapp']
INFO:     Started server process [20312]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
INFO:     Uvicorn running on http://localhost:4000 (Press CTRL+C to quit)

Python, Uvicorn & OS Version

Running uvicorn 0.23.2 with CPython 3.12.0 on Linux

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[james-emerton]

I am also seeing this issue. A quick look in the code suggests that it is not supported when calling Server.run() directly. See the implementation of uvicorn.run() here:

uvicorn/uvicorn/main.py

Lines 570 to 572 in 5bf788f

	if config.should_reload:
	sock = config.bind_socket()
	ChangeReload(config, target=server.run, sockets=[sock]).run()

I don't think this is currently possible; when reload=True the parent process creates the socket and passes it to a child process that terminates and restarts whenever there is a change. If you're starting with a running event loop, it's going to be in the parent process rather than the process that actually ends up serving requests.

In theory, you could accomplish this when starting with Config and Server instances by duplicating what's in uvicorn.run(). Indeed you could do the same from an async context with a bit of work, but it isn't likely to accomplish what you're looking for.

I think a small tweak to the documentation would be helpful. It could also be argued that reload should not be a Config parameter, as it will only be used by uvicorn.run()