Dispatch without FastAPI

[achille-roussel]

This PR relates to dispatchrun/dispatch#12 and dispatchrun/dispatch#19, and is intended to make FastAPI an optional dependency for Dispatch.

I first went down the path of using the gRPC service as a replacement; however, requiring HTTP/2 made a few things difficult since the CLI will attempt HTTP/1 requests (because the connectrpc protocol allows it); see dispatch.grpc.

Rather than hacking something with fake certs and whatnot, I added another implementation using http.server, which is very similar to the one with FastAPI but integrates with the standard library only; see dispatch.http.

This is still work in progress, I need to add tests.

[vadimdemedes]

This will be great for onboarding 👍

[chriso]

What happens if you Ctrl+C out of the blocking call? Should we catch KeyboardInterrupt and pass so that an exception isn't raised and stack trace printed?

[achille-roussel]

This happens:

$ ./dispatch run -- ./main.py

  ╭───────────────────────────────────────────────────────────────────╮
  │                                                                   │
  │  Starting Dispatch session: ce77804d-b40d-4df7-b8a4-d10afcc4ab31  │
  │                                                                   │
  │  Run 'dispatch help run' to learn about Dispatch sessions.        │
  │                                                                   │
  ╰───────────────────────────────────────────────────────────────────╯

Hello, World!
127.0.0.1 - - [22/Apr/2024 18:22:23] "POST /dispatch.sdk.v1.FunctionService/Run HTTP/1.1" 200 -
^C
  ╭────────────────────────────────────────────────────────────────────────────────╮
  │                                                                                │
  │  To resume this Dispatch session:                                              │
  │                                                                                │
  │      dispatch run --session ce77804d-b40d-4df7-b8a4-d10afcc4ab31 -- ./main.py  │
  │                                                                                │
  ╰────────────────────────────────────────────────────────────────────────────────╯

[chriso]

Ah right because we send SIGTERM rather than passing on the signal the CLI receives here: https://github.com/stealthrocket/dispatch/blob/00ad5441b8da130d378af1843af364241906b828/cli/run.go#L171. I think I had it passing on the signal originally, but uvicorn was handling SIGINT differently when it was run inside the CLI (and wasn't itself interactive) and it was printing a nasty stack trace.