Deploying inside a process manager: must account for inherited socket family and type

Hi,

I get an error when trying to run uvicorn with Circus, but only if using a socket with file descriptor (which I’d like to do to increase the number of processes).

circus.ini:

[socket:web]
host = 0.0.0.0
port = 80
[watcher:uvicorn]
cmd = uvicorn
# args = --host 0.0.0.0 --port 80 satemo.asgi:application 
# --> works ok
args = --fd $(circus.sockets.web) satemo.asgi:application 
# --> Fails
use_sockets = True
numprocesses = 1

Error:

File "c:\nss\venv\channels2\lib\site-packages\uvicorn\main.py", line 247, in startup
    sock = socket.fromfd(config.fd, socket.AF_UNIX, socket.SOCK_STREAM)
UnboundLocalError: local variable 'socket' referenced before assignment

Environment:

• Windows 10
• Python 3.6.5
• uvicorn 0.4.1

[ldanielburr]

Hi, just bumping this issue to note that I get this error on macOS, running uvicorn under supervisord.

Interestingly, I tried adding “import socket” at the top of the file, as was done in https://github.com/encode/uvicorn/pull/296, but that did not solve the issue. What did work was adding “import socket” right after line 352:

elif config.fd is not None:
    # Use an existing socket, from a file descriptor.
    import socket
    sock = socket.fromfd(config.fd, socket.AF_UNIX, socket.SOCK_STREAM)

[jxrossel]

According to the socket module documentation:

The address family should be AF_INET (the default), AF_INET6, AF_UNIX, AF_CAN, AF_PACKET, or AF_RDS. The socket type should be SOCK_STREAM (the default), SOCK_DGRAM, SOCK_RAW or perhaps one of the other SOCK_ constants. The protocol number is usually zero and may be omitted or in the case where the address family is AF_CAN the protocol should be one of CAN_RAW, CAN_BCM or CAN_ISOTP.

I’d suggest to require full strings (e.g. ‘AF_INET’) and then get the constant values with getattr( socket, user_given_input ). To avoid following up with the versions of Python, I would not bother checking the arguments, but just return the exceptions given by socket, either at the getattr or socket.fromfd() levels.