[mysql] distinguish mysql-python instrumentation

[palazzem]

What it does

The current mysql integration supports only mysql-connector package. Other libraries such as MySQL-Python, must be handled differently. However, the current integration loader ( available in the monkey module) doesn't give the right feedback to developers, and indeed the error output is misleading.

Testing the loader

import logging

logger = logging.getLogger()
logger.setLevel(logging.DEBUG)

from ddtrace import patch, patch_all
patch_all()

The library MySQL-Python is installed in the environment so patch_all() should not find this integration.

Before the patch

DEBUG:root:failed to patch mysql: module not installed

It seems that mysql is not installed while it is.

After the patch

DEBUG:root:failed to patch mysql: integration not available

The integration mysql is not available for this package.

[palazzem]

The error must be an ImportError because it's like if we're trying to import a module that is not here. However, the message may be different?

[vlad-mh]

I'm completely fine with this patch.

Though I'm having a hard time seing why we don't just do import _mysql and let the python runtime raise for us, instead of using utils.require_module. Did I miss something?

[palazzem]

This change is only temporary and at some point we will have the right instrumentation here (so the __init__.py knows which instrumentation must be activated). I've left the structure as before so that we should only remove the ImportError and add our imports.

Anyway, here we still have 2 different libraries that should not fail fast at the first ImportError.

[vlad-mh]

Makes sense. LGTM

[palazzem]

Thanks for the review @MattHauglustaine ! We still have room of improvement here! 👍

[LotharSee]

LGTM