Make parsing parameter from CLI work properly when it is a list

[dangquangdon]

Let argparser knows how to properly parse the parameter of type list by providing a callback that split the parameter using comma as default.

[akx]

Can we have a test for this, please?

AFAIK nargs="+" will assume the user enters the argument as

$ python foo.py --my-list-argument a b c d --other-argument blah

so a test would at least demonstrate that that's the way to use this feature.

[dangquangdon]

@akx I changed the approach and also described it in the PR description

[akx]

I emdraftened this – I think we need to design this new stepconfig.json thing a little more first since it'd be forever a part of the /valohai/ mount structure (and would need to eventually be documented like the others at https://docs.valohai.com/hc/en-us/articles/18704309491473-System-Configuration-Files and so on).

[dangquangdon]

I emdraftened this – I think we need to design this new stepconfig.json thing a little more first since it'd be forever a part of the /valohai/ mount structure (and would need to eventually be documented like the others at https://docs.valohai.com/hc/en-us/articles/18704309491473-System-Configuration-Files and so on).

Good to know that we have to document it publicly 👍 . My idea is stepconfig.json is simply just the information of the step defined in valohai.yaml 🤔

[dangquangdon]

@akx I reduce the scope of this PR now to only parse the parameter's value using comma as default. We will make further changes once we find out a good way to get multiple-separator from peon and roi

[akx]

👍