Regression in RunnerClient argument handling

[whiteinge]

There is a regression in how RunnerClient handles args/kwargs in develop (tested on dd80bec). This will affect people calling runners via the Python API and salt-api.

@DmitryKuzmenko I apologize for not reading pull req #24831 more closely. The fix needs to be in RunnerClient and not in the rest_cherrypy module. We must maintain a backward compatible RunnerClient interface. Commit 954ba6e needs to be reverted.

[DmitryKuzmenko]

As I can see there are 2 ways to provide fun args to RunnerClient:

1. Explicitly via low['args'] and low['kwargs'], for example:

{
    'client': 'runner',
    'fun': 'jobs.list_job',
    'args': (jid,),
}

or

{
    'client': 'runner',
    'fun': 'jobs.list_job',
    'kwargs': {'jid': jid},
}

1. Implicitly by not specifying 'args' and 'kwargs' in low and put kwargs directly into low:

{
    'client': 'runner',
    'fun': 'jobs.list_job',
    'jid': jid,
}

This worked as the 2nd one until #20161 added by @cachedout where default empty 'args' and 'kwargs' were forced. There are no references to related issues so I can't understood do we really need it?

[whiteinge]

@DmitryKuzmenko great reply. Thank you for tracking down all that info! The first two are clearly better formats (and more consistent with the rest of Salt). That said, we must retain support for that last format you mentioned (repeated below) otherwise we will break people's scripts who are already sending that via Salt's API or the REST API. If we want to phase it out it will need to go through the full multi-release deprecation path with code warnings and release notes. ``` { 'client': 'runner', 'fun': 'jobs.list_job', 'jid': jid, } ```

[DmitryKuzmenko]

@whiteinge as I can see to fully support the old way we have to determine what arguments could be passed to the requested function and bring the only needed arguments from the top-level:
{'jid': 123} -> {'jid': 123, 'kwargs': {'jid': 123}} if function supports jid argument.
{'jid': 123} -> {'jid': 123, 'kwargs': {}} if not.
In this case we'll need to lookup the requested function on the runner client side (salt-api in this case)
If it's acceptable I can use salt.minion.load_args_and_kwargs()

[whiteinge]

The `salt.utils.format_call()` function performs that functional introspection and arg/kwarg mapping. The RunnerClient() function should already be calling that somewhere.

[DmitryKuzmenko]

Ok, will do in this way. Thank you!