Support recursively loading from directories

[quodlibetor]

This is particularly nice for production systems that have potentially large number of config files (e.g. nginx, apache). I think that the sensu docs in particular describe the behavior and motivation pretty well.

[mehcode]

Here's what I understand about what we want here:

• Select N files using a glob syntax conf/**/*.conf
• Merge files together in lexical order 00-file.conf is added before 01-file.conf

Does it make sense to add this "glob" API to the existing config::File source API? Or, should it be its own API?

config::merge(config::File::from_glob("conf/**/*.conf"));

// or

// Not a fan of 'config::FileGlob' but I'm sure we could think of a better name
config::merge(config::FileGlob::new("conf/**/*.conf"));

[mehcode]

Decided to go with

config::File::with_pattern("conf/**/*.toml")

[quodlibetor]

Is that a helper that delegates internally to a merge function? That API seems pleasant, and exposing something that accepts an iterable of (already ordered) Paths would also be nice.

[mehcode]

I was going to make this an optional feature and delegate to https://doc.rust-lang.org/glob/glob/fn.glob.html

---

What you're talking about actually makes a lot of sense. I didn't think of it before but we could easily just impl From<Path> for File

config::File::from(Path::new("/tmp/foo/bar.json"));
config::File::from(vec![Path::new("/tmp/foo/bar.json"), Path::new("/tmp/a/foo.toml")]);
config::File::from(Path::new("/tmp/foo/bar.conf")).format(config::FileType::Json);

[quodlibetor]

Yup, with_pattern(&str) is the more ergonomic option, but implementing for Path and IntoIterator<Item=Path> is more flexible.

[mehcode]

Decided to just do the from path approach.

https://github.com/mehcode/config-rs/blob/master/examples/pattern/src/main.rs#L40-L45

I feel that's ergonomic enough for this use case and is far more flexible in the long run.