Fix several bugs in slack_webhook returner

[cdalvaro]

What does this PR do?

This PR fixes some issues detected by @max-arnold on #55342

What issues does this PR fix or reference?

Simple states like test.ping did not work with this returner.

Tests written?

👍

Commits signed with GPG?

👍

[max-arnold]

@sagetherage Could you please label this for Neon? (this is a bugfix for a new feature that was merged to Neon)

[max-arnold]

@cdalvaro Better, but is not quite there yet:

salt minion1 grains.items --return slack_webhook

2020-01-24 22:53:25,960 [salt.minion      :1819][ERROR   ][19444] The return failed for job 20200125065325865518: 'str' object has no attribute 'get'
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/salt/minion.py", line 1810, in _thread_return
    minion_instance.returners[returner_str](ret)
  File "/usr/lib/python3/dist-packages/salt/returners/slack_webhook_return.py", line 364, in returner
    report = _generate_report(ret, show_tasks)
  File "/usr/lib/python3/dist-packages/salt/returners/slack_webhook_return.py", line 306, in _generate_report
    returns = _process_returns(returns)
  File "/usr/lib/python3/dist-packages/salt/returners/slack_webhook_return.py", line 237, in _process_returns
    key=lambda s: s[1].get('__run_num__', 0)
  File "/usr/lib/python3/dist-packages/salt/returners/slack_webhook_return.py", line 237, in <lambda>
    key=lambda s: s[1].get('__run_num__', 0)
AttributeError: 'str' object has no attribute 'get'

I didn't test this thoroughly, but you can prevent the above traceback by adding the following function:

def _state_return(ret):
    '''
    Return True if ret is a Salt state return
    :param ret: The Salt return
    '''
    ret_data = ret.get('return')
    if not isinstance(ret_data, dict):
        return False

    return ret_data and '__id__' in next(iter(ret_data.values()))

And then replacing if isinstance(returns, dict): with if _state_return(ret):.
Please test it with other often used execution modules.

Also a small usability nitpick. Instead of:

webhook_url = 'https://hooks.slack.com/services/{}'.format(webhook)

Try this:

from salt.ext.six.moves.urllib.parse import urljoin as _urljoin

webhook_url = _urljoin('https://hooks.slack.com/services/', webhook)

This way specifying full webhook URLs would also work:

In [1]: from salt.ext.six.moves.urllib.parse import urljoin as _urljoin

In [2]: _urljoin('https://hooks.slack.com/services/', 'T00000000/B00000000/XXXXXXXXXXXXXXXXXXXXXXXX')
Out[2]: 'https://hooks.slack.com/services/T00000000/B00000000/XXXXXXXXXXXXXXXXXXXXXXXX'

In [3]: _urljoin('https://hooks.slack.com/services/', 'https://hooks.slack.com/services/T00000000/B00000000/XXXXXXXXXXXXXXXXXXXXXXXX')
   ...:
Out[3]: 'https://hooks.slack.com/services/T00000000/B00000000/XXXXXXXXXXXXXXXXXXXXXXXX'

In [4]: _urljoin('https://hooks.slack.com/services/', 'https://whatever.slack.com/T00000000/B00000000/XXXXXXXXXXXXXXXXXXXXXXXX')
   ...:
Out[4]: 'https://whatever.slack.com/T00000000/B00000000/XXXXXXXXXXXXXXXXXXXXXXXX'

[cdalvaro]

Thank you very much for all your help, @max-arnold

I start working on it right now!

[max-arnold]

@cdalvaro AFAIK, there is no need to modify the man page. It will be automatically generated before the release.

[sagetherage]

I have labeled @max-arnold but it needs to be rebased with Master and it needs to pass the build to get into Neon.

[cdalvaro]

All my tests are passing, but each time I merge the master branch with mine, distinct platforms/environments fail by different reasons.

[garethgreenaway]

@cdalvaro I've restarted the tests that were failing and will monitor them to ensure we can get this merged.

[cdalvaro]

@garethgreenaway, could you restart tests for ci/py2/centos6, it seems that failing tests are not related with my changes.

Thank you in advance!

[cdalvaro]

test.ping @garethgreenaway

[cdalvaro]

OMG! All checks have passed! 🎉