Allow configuration via TOML file

[rslota]

No description provided.

[michalwski]

Thanks for introducing the TOML configuration file. I think that more convenient would be to load the TOML config file first (if present) and allow to override some config options with evn vars. Do you think this is possible and make sense?

After my first review focused mostly on the code, I didn't find anything requiring a change.
It'd be good to add some tests, which as far as I know you are going to do.

[chrzaszcz]

Technical review: looks good, one minor question.

The overall impression is that overriding the options is a bit complicated and inconsistent (in the code) but acceptable.

Language check recommended, multiple articles missing and "it's" instead of "its", @goddammit

[chrzaszcz]

why change debug to error?

[rslota]

Because it's annoying to deal with sheer volume of debug logs, when developer just wants to enter application's shell and actually see commands you execute. As developer I don't need debug logs more often then I need them, so I prefer to have to enable debug logs explicitly, instead of constantly switching them off ;)

[NelsonVides]

Thank you!

[rslota]

Yeah, that ^ :D

[chrzaszcz]

Yeah, now it's explicit. I couldn't find it in the PR description somehow ;-)
It's good to describe such things so they don't look like mistakes.

[goddammit]

it might very well be that "unset" is correct in that context

[rslota]

Thanks for introducing the TOML configuration file. I think that more convenient would be to load the TOML config file first (if present) and allow to override some config options with evn vars. Do you think this is possible and make sense?

After my first review focused mostly on the code, I didn't find anything requiring a change.
It'd be good to add some tests, which as far as I know you are going to do.

You're right, I haven't though about it. Maybe indeed it would be nice to reverse that. I will give it a bit of time, but this will not be trivial. Confex env configuration is based on original sys.config that get's pretty much destroyed with TOML changes. We would need to preserve somehow original sys.config, and right now I don't see any non-hacky way to do that.
The other way around (like now) works, because, TOML configures based on different, external file, so it doesn't require Confex to work at all.

[rslota]

@michalwski @leszke It's not easy to override TOML with env variables - to do this in non-hacky way, we would need to rethink the env configuration, as Confex library doesn't work well in such scenario.
That being said, I consider this PR ready to be merged. Please re-review :)