igluctl: switch severity level to skip checks

[chuwy]

Currently severity levels assume that we can have better or worse (high quality/low quality) checks, whereas it really not high/low, but include/exclude. User should have an ability to disable/enable each particular check if he is sure that absence of maxLength is fine.

My idea is to switch severity levels with checks option (or even --skip-checks), so user will have explicitly skip some lint if he wants: igluctl lint /path/ --skip-checks optionalNull,implicitMax, where optionalNull disables #231 check and implicitMax disables #175.

[chuwy]

Hey @oguzhanunlu, here's another piece of info.

Yes, we're going to get rid of notion of levels entirely as well as of --severityLevel option and instead skip each linter individually. Otherwise your approach looks quite correct.

You can have a map of linters:

val allLinters: Map[String, Linter] = Map(
  "minimumMaximum" -> lintMinimumMaximum,
  "minMaxLength" -> lintMinMaxLength,
...etc)

Then just get Linters by their keys from provided input:

val lintersToUse = lintersToSkip.foldLeft(Right(allLinters.values)) { (linters, cur) =>
  (linters, allLinters.get(cur)) match {
    case (Right(linters), Some(c)) => Right(linters.diff(List(c)))
    case (Left(errors), Some(_)) => Left(errors)
    case (Right(_), None) => Left(List(s"Unknown linter $cur"))
    case (Left(errors), None) => Left(s"Unknown linter $cur" :: errors)
  }
}

[chuwy]

I'm also quite keen to have different sets of linters for different use cases, like redshift, config, etc. But not for this time.

[alexanderdean]

I'm also quite keen to have different sets of linters for different use cases

That's a nice idea.

[chuwy]

Hey @oguzhanunlu, just a quick reminder to add description of all new linters Igluctl wiki page ("Update documenation" card in project this time is after you!)