fix: solara run should only print url when the server is running

[maartenbreddels]

If it takes a bit for a server to start, you will click the url and it will not work.

[render]

Your Render PR Server URL is https://solara-stable-pr-776.onrender.com.

Follow its progress at https://dashboard.render.com/web/srv-crcpiajtq21c73cv3al0.

[iisakkirotko]

There are a couple issues present (at least on my machine?) that seem a bit mysterious to me:

• if I run solara run solara.website.pages -a only Solara server is starting... gets printed, even though the server itself runs fine, and the can be connected to
• if I run solara run solara.website.pages, I get an internal server error, because of:

ERROR:    Exception in ASGI application
Traceback (most recent call last):
  File "/Users/iisakki/micromamba/envs/solara-dev/lib/python3.10/site-packages/uvicorn/protocols/http/h11_impl.py", line 407, in run_asgi
    result = await app(  # type: ignore[func-returns-value]
  File "/Users/iisakki/micromamba/envs/solara-dev/lib/python3.10/site-packages/uvicorn/middleware/proxy_headers.py", line 69, in __call__
    return await self.app(scope, receive, send)
  File "/Users/iisakki/micromamba/envs/solara-dev/lib/python3.10/site-packages/starlette/applications.py", line 123, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/Users/iisakki/micromamba/envs/solara-dev/lib/python3.10/site-packages/starlette/middleware/errors.py", line 186, in __call__
    raise exc
  File "/Users/iisakki/micromamba/envs/solara-dev/lib/python3.10/site-packages/starlette/middleware/errors.py", line 164, in __call__
    await self.app(scope, receive, _send)
  File "/Users/iisakki/micromamba/envs/solara-dev/lib/python3.10/site-packages/starlette/middleware/gzip.py", line 24, in __call__
    await responder(scope, receive, send)
  File "/Users/iisakki/micromamba/envs/solara-dev/lib/python3.10/site-packages/starlette/middleware/gzip.py", line 44, in __call__
    await self.app(scope, receive, self.send_with_gzip)
  File "/Users/iisakki/Code/widgetti/solara/packages/solara-enterprise/solara_enterprise/auth/middleware.py", line 127, in __call__
    await self.app(scope, receive, send_wrapper)
  File "/Users/iisakki/micromamba/envs/solara-dev/lib/python3.10/site-packages/starlette/middleware/authentication.py", line 49, in __call__
    await self.app(scope, receive, send)
  File "/Users/iisakki/micromamba/envs/solara-dev/lib/python3.10/site-packages/starlette/middleware/exceptions.py", line 65, in __call__
    await wrap_app_handling_exceptions(self.app, conn)(scope, receive, send)
  File "/Users/iisakki/micromamba/envs/solara-dev/lib/python3.10/site-packages/starlette/_exception_handler.py", line 64, in wrapped_app
    raise exc
  File "/Users/iisakki/micromamba/envs/solara-dev/lib/python3.10/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    await app(scope, receive, sender)
  File "/Users/iisakki/micromamba/envs/solara-dev/lib/python3.10/site-packages/starlette/routing.py", line 756, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/Users/iisakki/micromamba/envs/solara-dev/lib/python3.10/site-packages/starlette/routing.py", line 776, in app
    await route.handle(scope, receive, send)
  File "/Users/iisakki/micromamba/envs/solara-dev/lib/python3.10/site-packages/starlette/routing.py", line 297, in handle
    await self.app(scope, receive, send)
  File "/Users/iisakki/micromamba/envs/solara-dev/lib/python3.10/site-packages/starlette/routing.py", line 77, in app
    await wrap_app_handling_exceptions(app, request)(scope, receive, send)
  File "/Users/iisakki/micromamba/envs/solara-dev/lib/python3.10/site-packages/starlette/_exception_handler.py", line 64, in wrapped_app
    raise exc
  File "/Users/iisakki/micromamba/envs/solara-dev/lib/python3.10/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    await app(scope, receive, sender)
  File "/Users/iisakki/micromamba/envs/solara-dev/lib/python3.10/site-packages/starlette/routing.py", line 72, in app
    response = await func(request)
  File "/Users/iisakki/Code/widgetti/solara/solara/server/starlette.py", line 432, in root
    content = server.read_root(request_path, root_path)
  File "/Users/iisakki/Code/widgetti/solara/solara/server/server.py", line 283, in read_root
    default_app = app.apps["__default__"]
KeyError: '__default__'

These issues are only present on this branch and don't happen on master. Although I'm also not sure if they are directly caused by the changes here or something else...

[iisakkirotko]

Would it be nicer to leave the Solara server is starting... in, and print Solara server started at {url} in green after?

[maartenbreddels]

yeah, maybe the \r can be removed.

[iisakkirotko]

So I think I've solved my second issue

if I run solara run solara.website.pages, I get an internal server error, because of:

This is due to the change in import order. Because we now import solara.server.server, which in turn imports from . import app, app.py runs before this line. Then app.apps is empty, and the server can't start.

For a solution, we could import solara.server.server here instead of at the top, although I'm not sure if this could introduce a race condition of some sort.

Suggested change

	while not failed and (server is None or not server.started) or not solara.server.server.is_ready(url):
	import solara.server.server
	while not failed and (server is None or not server.started) or not solara.server.server.is_ready(url):

Another option would be to move this check down to below where we set environmental variables.