Try to be more helpful when JSON gives up

[Qalthos]

SUMMARY

When bundling params to JSON for ansible-connection, try to be clearer when problems occur about what has gone wrong.

ISSUE TYPE

• Bugfix Pull Request

COMPONENT NAME

module_utils/connection.py

ANSIBLE VERSION

2.8

[webknjaz]

You might want to use six.raise_from

[Qalthos]

I'm not sure how that helps on Python 2. I don't want to bury the original exception, as that is the one with the details to diagnose an issue, but I also want a more specific message to clue the issue in the right direction.

[bcoca]

on the core side we have orig_exec on AnsibleError to allow chaining the exception info, maybe something similar could be added here to the exception objects used?

[webknjaz]

@Qalthos it won't bury the original exception, it's just a way to spell raise ConnectionError from orig_exc without actually using a syntax, unavailable under Python 2.

[Qalthos]

it won't bury the original exception, it's just a way to spell raise ConnectionError from orig_exc without actually using a syntax, unavailable under Python 2.

Maybe I'm missing something, but it does not seem to do anything like that on Python 2

Python 3.7.0 (default, Jul 15 2018, 10:44:58) 
[GCC 8.1.1 20180531] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from ansible.module_utils.six import raise_from
>>> e1 = Exception("Exception 1")
>>> e2 = Exception("Exception 2")
>>> raise_from(e1, e2)
Exception: Exception 2

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 3, in raise_from
Exception: Exception 1
>>> 

This is... fine, it gets the point across and lets me keep the original message while specifying cause.

Python 2.7.15 (default, Jun 27 2018, 13:05:28) 
[GCC 8.1.1 20180531] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from ansible.module_utils.six import raise_from
>>> e1 = Exception("Exception 1")
>>> e2 = Exception("Exception 2")
>>> raise_from(e1, e2)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/nate/workspace/ansible/ansible/lib/ansible/module_utils/six/__init__.py", line 744, in raise_from
    raise value
Exception: Exception 1
>>> 

Here, however... e2 is lost, unless you mean to imply that I might want this in addition to adding the original exception text to the new exception which seems redundant in the Python 3 case. Maybe I am completely misunderstanding what you mean, but I don't really see how this helps me.

[Qalthos]

on the core side we have orig_exec on AnsibleError to allow chaining the exception info, maybe something similar could be added here to the exception objects used?

I had seen that, but couldn't find how it was used. The only thing I can find is https://github.com/bcoca/ansible/blob/devel/bin/ansible#L149. It doesn't look like just popping an orig_exc on to the ConnectionError will trigger that though, and it seems to provide roughly the same functionality as what I am already doing anyway, unless I'm missing something.

[webknjaz]

@Qalthos exactly, it does nothing under py2, but adds explicit cause under py3. But now that I think about it, it's probably a default behavior anyway.