Standardize on filename extensions for Butane and Ignition configs

[jlebon]

For our own documentation, we should be consistent about the filename extension used for Butane and Ignition configs. I'm not sure how consistent we are today, but for Ignition it's usually .ign, though many people also use .json. Similarly for Butane (previously FCCT), it's usually .fcc though .yaml is also used.

The argument for using .ign and .fcc is that it's more specific. The argument for .json and .yaml is that they're well-known extensions which means e.g. easier editor integration, rendering, etc...

@dustymabe proposed using .ign.json and .bu.yaml as an in-between solution.

[bgilbert]

The current plan of record is to switch to .bu for Butane configs, but I think Dusty's proposal is worth considering. I personally don't like a bare .json/.yaml, since they denote a detail of the format rather than the identity of the format.

To be clear, there's no code that cares about the filename extensions AFAIK, so this is just a matter of convention.

[dustymabe]

I'm 👍 for Dusty's proposal 🤣.

Anybody else want to weigh in?

[lucab]

While a bit longer, I also like that double-suffix approach.

[travier]

Maybe we could use the double extensions while we figure out how to get bu=yaml and ign=json syntax highlight in the most common places (vim, emacs, VSCode, EditorConfig should cover a large ground) and then switch to single extensions?

[travier]

Existing IANA assignment for Ignition: https://www.iana.org/assignments/media-types/application/vnd.coreos.ignition+json

[dustymabe]

We discussed this in the meeting today.

13:30:31*       dustymabe | #agreed we'll go with the .bu .ign extension for new files in our
                          | documentation and we'll try to use those suffixes for consistency in
                          | issues/examples we post