fix: Replace exception logger function with logger.exception

[sondrelg]

This PR tweaks the way errors are logged, to include more metadata.

I didn't spend a lot of time crafting the logger messages, so suggestions for better ones are very welcome 🙂

Motivation

We use Sentry for errors, and saq currently logs job exceptions in a way that's slightly too generic for Sentry. Since the plaintext dump of a traceback is logged without any extra information, all errors raised by saq are bundled together. Moreover, there is a size limit to log message length in Sentry, so we're not even receiving the full tracebacks (see screenshot at the bottom of the comment below).

Using logger.exception or logger.error(..., exc_info=True) (they're the same thing), we're able to get proper Sentry events, containing the complete traceback plus "breadcrumbs"

[sondrelg]

To test, I created his task function to run. Once on the latest release, and once with the fork:

def bad_function(ctx):
    raise ValueError('I fail now beep boop')

Here is the Sentry event produced with latest saq release:

In case you can't tell, this page actually has zero references to the actual error 😛

And here is the Sentry event produced with the fork branch:

The second one could also use some extra information, but at least now we get the code that raised the exception in focus, rather than have it maybe be included in the traceback plaintext dump.

Another thing to mention is that Sentry's logging integration cuts off long log messages, so the plaintext dump (for us) gets chopped in half hehe

[tobymao]

what is the result in the command line?

[barakalon]

Sweet.

I'm pretty sure the stream handler dumps the exception info properly.

[tobymao]

thanks @barakalon

and thanks @sondrelg for the PR