feat(translator): Set zone for endpoint and arrange endpoints by zone in EDS

[aoledk]

What this PR does / why we need it:

Set zone for endpoint and arrange endpoints by zone in EDS if zone is available in EndpointSlice. This is required before users can apply priority levels or zone aware routing load balancing strategy.

Which issue(s) this PR fixes:

Fixes #3538

[arkodg]

this breaks weight based routing, currently a setting has a weight, and there's 1:1 b/w xds locality and IR setting

[arkodg]

this can be fixed by copying the IR setting weight into lbEndpoint.LoadBalancingWeight (currently set to 1) and removing the locality weight (or setting it to 1)

[aoledk]

It seems like splitting 1 backend with specific weight (as 1 IR setting) to multiple localities with same specific weight doesn't break weighted based routing.

Compared to your suggestion in which we assign the specific weight to individual endpoint, the same endpoint has same chance to be chosen by envoy.

Since EG has enabled locality weighted load balancing, we must set locality weight, or else the locality will not be assigned any load ¹.

gateway/internal/xds/translator/cluster.go

Lines 85 to 89 in 85cac84

	CommonLbConfig: &clusterv3.Cluster_CommonLbConfig{
	LocalityConfigSpecifier: &clusterv3.Cluster_CommonLbConfig_LocalityWeightedLbConfig_{
	LocalityWeightedLbConfig: &clusterv3.Cluster_CommonLbConfig_LocalityWeightedLbConfig{},
	},
	},

Footnotes

1. https://www.envoyproxy.io/docs/envoy/latest/api-v3/config/endpoint/v3/endpoint_components.proto#config-endpoint-v3-localitylbendpoints ↩

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 68.34%. Comparing base (4a74e60) to head (026f29f).

❗ Current head 026f29f differs from pull request most recent head eba8f1c

Please upload reports for the commit eba8f1c to get more accurate results.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3542      +/-   ##
==========================================
- Coverage   68.81%   68.34%   -0.47%     
==========================================
  Files         175      170       -5     
  Lines       21525    20770     -755     
==========================================
- Hits        14812    14196     -616     
+ Misses       5636     5556      -80     
+ Partials     1077     1018      -59     

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[aoledk]

/retest

[github-actions]

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