get_container returns None instead of the expected tuple

[Mehdi Abaakouk]

Hi,

During https://bugs.launchpad.net/tripleo/+bug/1751056 investigation, we discover that swiftclient get_container method sometimes returns None instead of the expected tuple or exception.

The following code:

        try:
            headers, files = self.swift.get_container(
                container, full_listing=True)
        except swclient.ClientException as e:

raise this exception because None is returned instead of the headers and files.

[Thu Feb 22 12:35:23.833389 2018] [:error] [pid 19] [remote 192.168.24.3:188] yield future.result()
[Thu Feb 22 12:35:23.833406 2018] [:error] [pid 19] [remote 192.168.24.3:188] File "/usr/lib/python2.7/site-packages/concurrent/futures/_base.py", line 422, in result
[Thu Feb 22 12:35:23.833438 2018] [:error] [pid 19] [remote 192.168.24.3:188] return self.__get_result()
[Thu Feb 22 12:35:23.833450 2018] [:error] [pid 19] [remote 192.168.24.3:188] File "/usr/lib/python2.7/site-packages/concurrent/futures/thread.py", line 62, in run
[Thu Feb 22 12:35:23.833820 2018] [:error] [pid 19] [remote 192.168.24.3:188] result = self.fn(*self.args, **self.kwargs)
[Thu Feb 22 12:35:23.833835 2018] [:error] [pid 19] [remote 192.168.24.3:188] File "/usr/lib/python2.7/site-packages/gnocchi/utils.py", line 312, in <lambda>
[Thu Feb 22 12:35:23.833862 2018] [:error] [pid 19] [remote 192.168.24.3:188] return list(executor.map(lambda args: fn(*args), list_of_args))
[Thu Feb 22 12:35:23.833873 2018] [:error] [pid 19] [remote 192.168.24.3:188] File "/usr/lib/python2.7/site-packages/gnocchi/storage/__init__.py", line 252, in _get_measures_timeserie
[Thu Feb 22 12:35:23.833893 2018] [:error] [pid 19] [remote 192.168.24.3:188] metric, aggregation.method, aggregation.granularity)
[Thu Feb 22 12:35:23.833903 2018] [:error] [pid 19] [remote 192.168.24.3:188] File "/usr/lib/python2.7/site-packages/gnocchi/storage/__init__.py", line 185, in _list_split_keys_for_metric
[Thu Feb 22 12:35:23.833921 2018] [:error] [pid 19] [remote 192.168.24.3:188] metric, aggregation, granularity, version)),
[Thu Feb 22 12:35:23.833931 2018] [:error] [pid 19] [remote 192.168.24.3:188] File "/usr/lib/python2.7/site-packages/gnocchi/storage/swift.py", line 167, in _list_split_keys
[Thu Feb 22 12:35:23.834481 2018] [:error] [pid 19] [remote 192.168.24.3:188] container, full_listing=True)
[Thu Feb 22 12:35:23.834555 2018] [:error] [pid 19] [remote 192.168.24.3:188] TypeError: 'NoneType' object is not iterable

[Christian Schwede (cschwede)]

I checked the python-swiftclient code; it must be an obscure circumstance where that happens. By default exceptions are either raised or a tuple is returned, and I wasn't able to spot a situation where this won't happen.

Can't verify this because we're lacking logs from Swift at that timepoint - so marking as incomplete for now.