Rationalize locations where dbc configs are stored

[ianmcook]

Currently on macOS:

• uid.uuid is created in ~/Library/Application Support/Columnar/dbc
• The credentials subdirectory (which contains columnar.lic and credentials.toml) is created in into ~/Library/dbc

Shouldn't we have these be in the same place?

[amoeba]

Yes. That was missed during review. These two categories of file use different code paths so we should refactor them into a common one too.

[amoeba]

I'll put a PR up for this later today.

[amoeba]

The actual bug was me here, sorry @zeroshade.

I suggested XDG_DATA_DIR and @zeroshade told me exactly where the credentials were going to go based on that (~/Library/dbc) and it didn't immediately strike me as odd. Looking around, it's not odd and it's even recommended,

Note: The ~/Library/Application Support directory is reserved for non-essential application resources like templates or plug-ins which may be changed by the user. It should not be used to store irreplaceable user data.

See https://developer.apple.com/library/archive/qa/qa1170/_index.html. Credentials could fall under this category, I'm not sure. Applications having a ~/Library/$app folder is not universal but it's not rare.

But I kept researching and we can make a pretty good argument that all of this guidance we're pulling from Apple is talking about Applications and we can further make the argument that dbc isn't an Application (for various reasons), so we're kind of making stuff up here even with using ~/Library at all. By some argument, we should've used ~/.config/dbc which is more common for CLI tools on macOS in my sampling. The reality is that no one is consistent about any of this.

If I were to do it again, I think I'd suggest we follow XDG more literally on macOS and use (1) ~/.config/dbc for config and (2) ~/.local/share/dbc for data/credentials which is how I interpret XDG.

Do you have any thoughts on this @ianmcook? I see an advantage to just having one folder on all platforms for all of dbc's files. I might sit on this for a couple of days and come at it with fresh eyes.