Accept trailing commas in list config type

[sjshuck]

Summary

It's not documented exactly what delimits a list. In the code, it's commas:

ansible/lib/ansible/config/manager.py

Line 94 in 3a1d58b

value = [unquote(x.strip()) for x in value.split(',')]

But trailing commas are not supported, because they introduce spurious empty string elements. It would be nice, since the INI-style config file format accepts multiline values de facto.

And of course, document all the above.

Issue Type

Feature Idea

Component Name

lib/ansible/config/manager.py

Additional Information

I'm preparing a PR for this. But first, please see #80907.

Code of Conduct

• I agree to follow the Ansible Code of Conduct

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Files identified in the description:

• lib/ansible/config/manager.py

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[bcoca]

this has an issue with the ability to add empty items to a list, specially if it is the last one

[sjshuck]

@bcoca Not if implemented correctly. I'll show the code I have in mind but I still would like #80907 addressed before I prepare a full PR with docs changes etc.

[sjshuck]

sjshuck@3cee653

You can have empty quotes ("", '') as a list element and it won't get filtered out. (Not so for pathlist, but an empty pathlist item doesn't make sense since paths cannot be empty.)

[bcoca]

empty path == relative path == cwd (current working directory)

[sjshuck]

I'm sure you know that . is the standard way to represent cwd, so I guess I don't know what you're saying. Are you suggesting someone might interpret an empty path that way in theory, or are you saying Ansible and/or some modules interpret it that way in practice?

Either way, no file API or OS I'm aware of considers the empty string to be a legal path, whether absolute or relative.

[sivel]

Python specifically is one of those things where an empty path effectively means cwd.

>>> import os
>>> os.path.abspath('')
'/home/sivel'

As such pretty much all of our code, including, but not limited to, resolve_path and unfrackpath works the same way. This makes the expectation of using an empty string as the cwd a reality.

We handle any cases where an empty string doesn't meet expectations on a case by case basis, and not on a global basis.

[sjshuck]

I didn't know that about Python. Thanks for explaining @sivel.

I was going to suggest that pathlist also unquote() elements, just like list does, but again that discussion probably belongs in #80907.

[sivel]

I should also note, that in our base.yml only 1 item uses pathlist (DEFAULT_HOST_LIST), and it's completely legal to supply an empty string there.

Also, for values supplied in ansible.cfg they are relative to the ansible.cfg, so an empty string there is equivalent to dirname of the ansible.cfg file.

[sjshuck]

So one of my goals in this and the other issue is to clearly document what the format is, even if it doesn't change.

Right now, you have things like this. It says type: list, but it isn't explained anywhere what that actually means. The default is surrounded with [...] which AFAICT from the code (I didn't test) would choke on those characters. Other options don't have those characters. I think it's possible to specify the list type in documentation in a succinct, friendly way.