Adds support for EndpointSlices API in master

[lafolle]

Adds support for endpoint slices api to fetch endpoints.

Corresponding clusterrole changes haproxy-ingress/charts#66

[monkeymorgan]

Note that @lafolle is not currently working on this (The 'in progress' comment might make you think there's more to come). He's away for the foreseeable, but I can try and answer any follow ups.

[jcmoraisjr]

Thanks for the update. I'll do my best to add it in the first v0.15 snapshot and I'll also try to add it in the first v0.14 stable or maybe in the first patch of that branch.

[jcmoraisjr]

Thank you for the contribution! Sorry about taking so much time to revise it.

See a few comments below.

[jcmoraisjr]

Folks, needed to merge #933, sorry. You can see some conflicts but all of them should be pretty simple to fix. The main issue however is that all the lister, informer and cache code base need to be written for the new controller, but you don't need to worry about that, I can take care of that if you prefer. Just run the controller with HAPROXY_INGRESS_RUNTIME=LEGACY, or adjust the code below, to make your local test.

haproxy-ingress/pkg/main.go

Lines 32 to 36 in df00660

	if strings.ToUpper(os.Getenv("HAPROXY_INGRESS_RUNTIME")) != "LEGACY" {
	launch.Run()
	return
	}
	hc := legacy.NewHAProxyController()

[lafolle]

Linter seems to be failing with new golangci-lint 1.52.2 while it passes for 1.51.2. Two options: 1) fix haproxy-ingress to satisfy the new linter 2) pin golangci-lint to 1.51.x.

[jcmoraisjr]

Thank you! See below a few more suggestions, and also:

• please remove revive from .golangci.yaml, this should fix the lint errors. I'll revisit the lint config and also the errors in a future pr;
• add the new option in command-line.md doc file;
• try to squash all the commits into a single one.

After that I'm done and we can merge. I'll prepare a cherry-pick for v0.14 later, as well as the v0.15 controller implementation. Thanks for all the effort put in this controller, that's very much appreciated.

[jcmoraisjr]

LGTM thanks! Merging now, v0.14 cherry-pick and v0.15 controller implementation coming soon.