Config file for rv

[deivid-rodriguez]

We've been delaying to get a configuration file in place for rv, but it's about time we add it.

Format

We want to use https://kdl.dev/.

Location

We'll probably want both a project specific location, (like one of rv.kdl, .config/rv.kdl, or .config/rv/rv.kdl) and a global location like one of ~/.rv.kdl, ~/.config/rv.kdl, or ~/.config/rv/rv.kdl).

Schema

The stuff that I recall has come up so far is

rv {
  // ruby version to be used by default when no tool files specify any version
  ruby "4.0"

  // path where `rv ci` installs gems to, and where `rv run` looks for installed gems
  gem-home "vendor/bundle"

  // to be defined in https://github.com/spinel-coop/rv/pull/562
  update-mode [check-for-updates, auto-install, none] 
}

There's also source credential configuration but we may want to keep those somewhere else, at least the credentials.

@indirect mentioned https://github.com/rust-cli/config-rs as potentially helpful (particularly to deal with the different level of configurations I guess, and backing it up with ENV variables, etc).

[zkat]

I have a config-rs KDL loader that can do a bunch of fallback from clap in fun ways, if y'all wanna take a look at that?

It lets you put settings in a set of KDL files, with fallback kdl files to different locations, which can be manually overridden with both command line flags, and with env flags, and it's able to handle things like value type conversions, key/value pairs, and lists as values. HMU and I'm happy to share the code and have y'all use it.

Oh yeah, and it knows how to do --no-foo as being the same as foo #false

[deivid-rodriguez]

That's awesome, André mentioned that https://github.com/rust-cli/config-rs had no built in kdl support, but that we could implement some trait to get it working. I wasn't expecting that to be available yet though, thanks so much ❤️

/cc @a-chacon since he showed interest in tackling this over at #562.

[a-chacon]

Yes! I am interested. The definition looks nice, the per project and global locations make a lot of sense, config-rs looks like a good alternative (there is also confy that can read and write!, and depend on etcetera for locating the files, so match with rv implementation). I know you probably discuss this with other maintainers, but I must ask: Why kdl? I mean is there a technical advantage of use it and not a widespread configuration format like toml, yaml or even json? Sorry, I don't want to sound rude 🥲 Just that I was doing research about it and I can't stop to think this hehe I found they mention mise in the page, but mise is not using kdl for user configurations (It is using it but for a usage fields or something like that). mise use toml for configs.

About the other theme, take a look to confy! I think it can help if we want to add also a command for modify configurations. (Ex: rv config set gem-home).

Anyway, I will continue taking a look to it during the week!

[indirect]

My biggest motivation for using KDL is that TOML array-handling often causes problems. I use TOML extensively for both https://gohugo.io and https://fly.io, and the array vs not-array is constantly a confusing struggle. KDL completely resolves this, IMO.

[simi]

@deivid-rodriguez do you think it is worth to try to contribute rust-cli/config-rs#498 back?

[deivid-rodriguez]

@simi Absolutely, I think it'd be a nice follow up after we get things working and battle tested. It may also help with wider kdl adoption.

@a-chacon Nice, thank you! Confy sounds interesting, I just wonder how it integrates with clap and kdl. Not against using something more minimal if we can implement the rest ourselves, just making sure we are fully aware of what we get and what we don't get by choosing a specific crate.