Added support for endpointslices

[ajaychoudhary-hotstar]

Description

Currently Ingress is doing service discovery from endpoint objects, there is is hard limit of 1K IP address that k8s endpoint objects can hold which breaks load balancing if some backends scale more than 1K.

Related Issues

(#5167)

Testing

Tested in lower env, scaled the backend system to 1.2K pods, and noticed the same 1.2K in backend metrics envoy_cluster_membership_total.

Checklist

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• I updated CONTRIBUTING.md with any special dev tricks I had to use to work on this code efficiently.

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[kflynn]

@ajaychoudhary-hotstar, many thanks for diving into this! The mechanics of how you're dealing with EndpointSlices look reasonable to me, but I need to make your life a little harder, I'm afraid -- I've run into at least one case where there were no EndpointSlices but there were Endpoints, so I think we should probably look at EndpointSlices if present and Endpoints if not. Does that sound sane?

[ajaychoudhary-hotstar]

@ajaychoudhary-hotstar, many thanks for diving into this! The mechanics of how you're dealing with EndpointSlices look reasonable to me, but I need to make your life a little harder, I'm afraid -- I've run into at least one case where there were no EndpointSlices but there were Endpoints, so I think we should probably look at EndpointSlices if present and Endpoints if not. Does that sound sane?

Thanks, @kflynn Have added endpoints as fallback.

[kflynn]

@ajaychoudhary-hotstar, I think this looks good, many thanks! Let me sort out CI for it...

[Alice-Lilith]

Nice, and thanks for the PR! 🙂 🚀