Master-port #52441

[mchugh19]

cron return a single line

What does this PR do?

Ports #52441 to master

Add get_entry to cron module to return a single cron entry. This allows for use in tools like saltcheck:

validate_cron.{{ task }}_exists:                                          
  module_and_function: cron.get_entry                                     
  args:                                                                   
    - root                            
    - {{ task }}                                                          
  assertion: assertEqual                                                  
  assertion_section: identifier                                           
  expected-return: {{ task }}

[dhiltonp]

This PR needs some tests.

It's a good candidate for unit tests - patch list_tab to return sample data, then verify that it breaks if cmd and identifier are specified, and works if identifier or cmd are specified.

Is it possible for the same identifier to occur multiple times in the crontab? What about the same command at different intervals?

[myii]

Apologies, I started that review weeks ago but I waited for the PR route but both were closed.

[dwoz]

@mchugh19 Can you address the comments?

[mchugh19]

Added tests and @myii's changes. I think this should be good to go!

[mchugh19]

re-run pr-py3-centos-8

[mchugh19]

re-run pr-ubuntu1604-py3-m2crypto

[mchugh19]

re-run pr-ubuntu1604-py2-m2crypto

[mchugh19]

re-run pr-amazon2-py2

[DmitryKuzmenko]

There are no py2 anymore. I've updated the branch to force refreshing of the tests list.