Config schema

[novopl]

What?

We should have a way to do some kind of config validation or at least the ability to print the whole config along with all the defaults.

Why?

• Validation. Ability to validate config on startup can detect a lot of configuration problems very early on.
• Config generation. Ability to generate much more complex config files. Those can be used as examples or scaffolds.
• Exporting configuration. Ability to export the current configuration along with default values (those could theoretically change between versions).

How?

Dynamic schema definition across modules

The schema could be built dynamically in the same way as requirements are. Each module containing the CLI commands definition should also call conf.schema() at the top to define
what config values it uses.

Merging all schemas into one

This might be tricky if the definitions of fields differ. Some kind of reconciliation algorithm is needed so if we have multiple definitions for the same field we can either merge them into one or fail.