PyDruids clients throw to generic Exceptions OSError

[sebtrack]

The error handling does not allow to manage exceptions when using PyDruid. For example, it's hard to catch an HTTP Error 504: Gateway Time-out and then initiate a retry. A connection refused would, on the other hand, be an exception to log with Sentry, etc. All the fine-grained HTTP client exceptions get the generic label OSError with a string describing it, which is a bad design decision.

pydruid/pydruid/client.py

Lines 554 to 577 in 98cab4d

	except urllib.error.HTTPError as e:
	err = e.read()
	if e.code == 500:
	# has Druid returned an error?
	try:
	err = json.loads(err)
	except ValueError:
	if HTML_ERROR.search(err):
	err = HTML_ERROR.search(err).group(1)
	except (ValueError, AttributeError, KeyError):
	pass
	raise IOError(
	"{0} \n Druid Error: {1} \n Query is: {2}".format(
	e,
	err,
	json.dumps(
	query.query_dict,
	indent=4,
	sort_keys=True,
	separators=(",", ": "),
	),
	)
	)