Provide an official JSON Schema for the config file

[jonasbb]

It would be great if dependabot could release an official JSON Schema for the config file format.
Ideally this would also be added to schemastore such that editors can pick up the new file automatically.
Publishing the schema allows users to benefit from auto completion in their editors, for example with VS Code.

It seems that the config validator on the dependabot website already uses a JSON schema, so it might be enough to simply publish that one.

[bmuskalla]

I took the liberty to do this. The pull requests has a full schema matching the current documentation on the website.
If you want to try this out locally, you can use VSCode + YAML
Given the pull request is not yet merged, you need this in your settings to enable the schema for the dependabot files:

"yaml.schemas": {
  "<path to schema>/dependabot.json": ".dependabot/config.yml",
}

Here is a quick preview how the file can now be edited within code

[feelepxyz]

@bmuskalla nice work! Sorry for not getting to this, we've ended up with a JSON schema which isn't directly usable for the entire config file so not sure how to best re-construct and publish it. We validate each update config against a different sub-schema to get better errors. Tried using anyOf to do this but this resulted in really poor errors.

I've just created a Gist with the one we use as we have some subtle differences between package managers: https://gist.github.com/feelepxyz/d2c8f58359f29a4b4cdc935530060aae

Would love any ideas on how we could build a usable single schema that generates good error messages.

[bmuskalla]

@feelepxyz thanks for sharing. Indeed, having validation for those subtle differences is super important. I think we're in luck here. JSON Schema draft-07 supports conditional subschemas (read if/then/else - who knew this was a thing) and it seems most json/yaml parsers do understand draft -07. A tried it out in a small example, at least validation works properly in VSCode. Example makes it so the valid options version_requirement_updates depend on the value of package_manager: https://gist.github.com/bmuskalla/a30b3387e5ed97195154e7ab692f2841

Would that work for you? If so, let me know and I can try to rework the schema to use the conditionals as well.

[feelepxyz]

@bmuskalla I'll give that a go when I get a moment, if it works we could easily add an API endpoint for the schema.

[thepwagner]

This is a duplicate of #1927