quart crashes when port is not in the host header

[klarose]

I have a service using quart. I tried to enable json_logging on it, but it fails every request like this:

Traceback (most recent call last):
  File "/usr/lib/python3.6/logging/__init__.py", line 994, in emit
    msg = self.format(record)
  File "/usr/lib/python3.6/logging/__init__.py", line 840, in format
    return fmt.format(record)
  File "/home/kyle/.local/lib/python3.6/site-packages/json_logging/__init__.py", line 221, in format
    "remote_port": request_adapter.get_remote_port(request),
  File "/home/kyle/.local/lib/python3.6/site-packages/json_logging/framework/quart/__init__.py", line 115, in get_remote_port
    return request.host.split(":", 2)[1]
IndexError: list index out of range

The reason is that the "Host" header does not have a port on it in most cases. Indeed, it is optional according to the standard: https://tools.ietf.org/html/rfc2616?spm=5176.doc32013.2.3.Aimyd7#page-128

Take the example quart service provided in README.md. Modify it to listen on port 80. curl localhost/ will cause it to crash.

Or, keep it at the default port(5000), and run `curl localhost:5000 -H "Host: localhost". It will again crash

Ultimately, we cannot rely on the listening port being in a header. Some options for a fix:

1. Return "-" if the split fails.
2. Try to extract the listening port from quart. Note that this may not be the port the client connected to the system on, since there may be a reverse proxy/DNAT in front of the service.
3. Don't expose the port at all (what value does it give? The service will log where it's listening when it starts).

As it stands, I cannot use this at all for quart, since I can't override the formatter for request context logs.

[bobbui]

Sorry I've been super busy, so PR is welcome!

[klarose]

Do you have any recommendations for a preferred fix?

[bobbui]

doing splitting in an optimistic manner is kind of bad. I think we better do it like this:

• Extract it from env var or Quart app
• If not available, try to extract from host
• If none available, return "-"