Quiet KeyboardInterrupt

[maxfischer2781]

Summary

This PR quiets the KeyboardInterrupt when quitting a programatic run of uvicorn.

• The default traceback is much shorter now. It shows that it originates in uvicorn and notes that it quits uvicorn to avoid confusing it with a regular error.

  New traceback

  INFO:     Started server process [33977]
  INFO:     Waiting for application startup.
  INFO:     Application startup complete.
  INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
  ^CINFO:     Shutting down
  INFO:     Waiting for application shutdown.
  INFO:     Application shutdown complete.
  INFO:     Finished server process [33977]
  Traceback (most recent call last):
    File "/Users/maxfischer/code_projects/uvicorn/run_uvicorn.py", line 3, in <module>
      uvicorn.run("test:dummy_app")
    File "/Users/maxfischer/code_projects/uvicorn/uvicorn/main.py", line 584, in run
      raise KeyboardInterrupt("quit uvicorn") from None
  KeyboardInterrupt: quit uvicorn
  

  Old traceback

  INFO:     Started server process [33710]
  INFO:     Waiting for application startup.
  INFO:     Application startup complete.
  INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
  ^CINFO:     Shutting down
  INFO:     Waiting for application shutdown.
  INFO:     Application shutdown complete.
  INFO:     Finished server process [33710]
  Traceback (most recent call last):
    File "/opt/homebrew/Cellar/python@3.12/3.12.2_1/Frameworks/Python.framework/Versions/3.12/lib/python3.12/asyncio/runners.py", line 118, in run
      return self._loop.run_until_complete(task)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "uvloop/loop.pyx", line 1517, in uvloop.loop.Loop.run_until_complete
  asyncio.exceptions.CancelledError
  
  During handling of the above exception, another exception occurred:
  
  Traceback (most recent call last):
    File "/Users/maxfischer/code_projects/uvicorn/run_uvicorn.py", line 3, in <module>
      uvicorn.run("test:dummy_app")
    File "/Users/maxfischer/code_projects/uvicorn/uvicorn/main.py", line 577, in run
      server.run()
    File "/Users/maxfischer/code_projects/uvicorn/uvicorn/server.py", line 65, in run
      return asyncio.run(self.serve(sockets=sockets))
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/opt/homebrew/Cellar/python@3.12/3.12.2_1/Frameworks/Python.framework/Versions/3.12/lib/python3.12/asyncio/runners.py", line 194, in run
      return runner.run(main)
             ^^^^^^^^^^^^^^^^
    File "/opt/homebrew/Cellar/python@3.12/3.12.2_1/Frameworks/Python.framework/Versions/3.12/lib/python3.12/asyncio/runners.py", line 123, in run
      raise KeyboardInterrupt()
  KeyboardInterrupt
  

• uvicorn.run now has a flag suppress_ki that completely silences the KeyboardInterrupt. This allows programmatic usage to almost restore the pre-Cooperative signal handling #1600 behaviour - the noisy exception is gone (as before), but triggering CTRL+C again still allows to shut down the program (as is usual for Python).

Open design decisions

Should suppress_ki default to True? It's no problem for the CLI to set it explicitly to False and async code (which motivated #1600) does not go through this function at all.

Is suppress_ki a suitable name? ki is commonly used as an abbreviation of KeyboardInterrupt (see e.g. trio) but usually only needed in very technical situations.

Checklist

• I understand that this PR may be closed in case there was no previous discussion. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.

[Kludex]

Why not always suppressing on uvicorn.run?

[maxfischer2781]

There should at least be some way to not suppress KI in CLI and programmatic use, since that is what well-behaved programs should do. I don't have any strong opinion on whether that should be the default or not, though.

[Kludex]

There should at least be some way to not suppress KI in CLI and programmatic use, since that is what well-behaved programs should do. I don't have any strong opinion on whether that should be the default or not, though.

I don't think it should on uvicorn.run, on Server.serve() makes sense.

I want to maintain the previous behavior.

[maxfischer2781]

Okay, see #2384.