kola: add new tracker_list field for denylist

[miabbott]

In openshift/os#595 and openshift/os#599, I found myself mixed up with
the support of the tracker field. It's defined as a string, so
magically hoping that a slice of strings would be supported was
misguided.

Decided to try adding support for a new tracker_list field for those
times when one issue just doesn't cut it.

This seemed more straight-forward than trying to manually unmarshal
the YAML or trying to find all the denylist documents in use.

[openshift-ci]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[miabbott]

Looking for feedback if this is desirable or not.

[cgwalters]

I'm fine with this, but it's not clear we benefit from an explicit list, e.g. we can also use space-separated strings, or have one entry be canonical and the other a comment e.g.

[saqibali-2k]

The new functionality makes sense to me 👍

[saqibali-2k]

Suggested change

	Tracker string `yaml:"tracker"`
	TrackerList []string `yaml:"tracker_list"`
	Tracker []string `yaml:"tracker"`

I think we can change Tracker to []string from string rather than adding a TrackerList which seems to be closer to the assumed functionality in the linked PRs. If we prefer to have a separate field, that works too!

[miabbott]

I tried the wholesale change from string to []string, but the YAML module is strict about the type (well, all of Golang is strictly typed...) so it blows up trying to unmarhsal the data:

cannot unmarshal !!seq into main.DenyListObj

See this example snippet I was playing with - https://play.golang.org/p/WxafbrQGuNe

[saqibali-2k]

Yep you're right that functionality isn't present, ignore the above suggestion.

[miabbott]

I'm fine with this, but it's not clear we benefit from an explicit list, e.g. we can also use space-separated strings, or have one entry be canonical and the other a comment e.g.

I like the idea of a single entry being canonical and having others as comments.

[miabbott]

Going to withdraw this suggestion; let's just a use single canonical URL for the tracker and add additional links as comments.