harden OSTypeProber with regex list against version updates

[wagnerd3]

We recently had the problem, that unknown vmware_ostype values are present on newer images, which makes the OSTypeProber render them invalid. This then causes wrong figures in billing.

In order to make this robust, we could go with regexes which replace the version numbers with placeholders. IMHO, this should be very safe, because a specific version number should not be an indicator to not bill an image. I copied the outdated list with specific entries to the test, so we make sure we don't loose any coverage.

cc @kc1r74p

[majewsky]

BoundedRegexp has a very limited cache for regex compilations. Putting this many regexes in there will make the cache perform very badly. Please compile the regexes explicitly, e.g.

var validVMWareOsTypeRegexes = []*regexp.Regexp{
  regexp.MustCompile(`^almalinux_64Guest$`),
  regexp.MustCompile(`^amazonlinux(\d+)_64Guest$`),
  ...
}

[majewsky]

I can reproduce the CI failure. Do you have the latest golangci-lint version locally (2.11.4)?

[github-actions]

Merging this branch will decrease overall coverage

Impacted Packages	Coverage Δ	🤖
github.com/sapcc/go-bits/liquidapi	18.26% (-0.10%)	👎

---

Coverage by file

Changed files (no unit tests)

Changed File	Coverage Δ	Total	Covered	Missed	🤖
github.com/sapcc/go-bits/liquidapi/constants.go	0.00% (ø)	0	0	0
github.com/sapcc/go-bits/liquidapi/ostype_prober.go	0.00% (ø)	1125 (+30)	0	1125 (+30)

Please note that the "Total", "Covered", and "Missed" counts above refer to code statements instead of lines of code. The value in brackets refers to the test coverage of that file in the old version of the code.

Changed unit test files

• github.com/sapcc/go-bits/liquidapi/constants_test.go