hide internal labels from UI

[sielakos]

Closes gravitational/webapps#1081

[jimbishopp]

Instead of repeating the same filtering logic in all locations and writing tests for each, why not create a function that removes labels from the map returned by GetAllLabels? That way we'd only need to test the new function rather than adding tests for all the places that require this logic.

func removeHiddenLabels(m map[string]string) map[string]string {
	for name := range m {
		if strings.HasPrefix(name, "teleport.internal/") {
			delete(m, name)
		}
	}
	return m // return map so it can be used directly in for loops
}

// ... then 
for name, value := range removeHiddenLabels(teleApp.GetAllLabels()) {

This would isolate all testing to this new func - no need to test all places where the labels are hidden. Also makes it much easier to add new scenarios for hidden labels.

[sielakos]

I agree that function would be good, I could go even deeper because there is no need to repeat logic appending Labels to slice. It looks exactly the same everywhere.

About tests, I actually would like to keep them. I would even love to add more unit tests for those functions, as they are not tested that way. Unless there is a reason not to.

[sielakos]

So with a bit of refactoring, I have added makeLabels function that does all the repetitive stuff related to labels.

1. transforming from maps to slice
2. filtering
3. sorting

I have also added tests for this function.

All that taken into account I would actually like to leave tests for MakeServers etc. as they are. If for no other reason than just to test that makeLabels is used.

[codingllama]

You've got a healthy number of active reviewers already, so I'm sitting this one out. (Feel free to re-add me if you need an extra pair of eyes.)

[r0mant]

lgtm after remaining comments are addressed