conf(*) allow to configure DnsLookupFamily for ads_cluster of XDS server

[slonka]

Summary

Allow users to configure DnsLookupFamily for ads_cluster of XDS server so that there are no unnecessary DNS queries.

Full changelog

• Implement xdsHostDnsLookupFamily field which allows to set dns lookup family if XDS host is a domain

Second approach: #4275

Issues resolved

Fix #2000

Documentation

Is there any docs on this?

• Link to the website documentation PR

Testing

• Unit tests
• E2E tests
• Manual testing on Universal
• Manual testing on Kubernetes

Backwards compatibility

• Update UPGRADE.md with any steps users will need to take when upgrading.
• Add backport-to-stable label if the code follows our backporting policy

[codecov-commenter]

Codecov Report

Merging #4264 (7bec648) into master (8545ba2) will increase coverage by 0.01%.
The diff coverage is 95.18%.

@@            Coverage Diff             @@
##           master    #4264      +/-   ##
==========================================
+ Coverage   55.68%   55.69%   +0.01%     
==========================================
  Files         935      935              
  Lines       56401    56421      +20     
==========================================
+ Hits        31405    31424      +19     
- Misses      22515    22517       +2     
+ Partials     2481     2480       -1     

Impacted Files	Coverage Δ
pkg/xds/bootstrap/template_v3.go	97.67% <92.72%> (-1.50%)	⬇️
pkg/config/xds/bootstrap/config.go	57.57% <100.00%> (+1.32%)	⬆️
pkg/xds/bootstrap/generator.go	58.68% <100.00%> (+0.19%)	⬆️
...s/authn/api-server/tokens/admin_token_bootstrap.go	82.00% <0.00%> (-4.00%)	⬇️
pkg/core/secrets/manager/global_manager.go	42.42% <0.00%> (-3.04%)	⬇️
pkg/core/tokens/default_signing_key.go	77.77% <0.00%> (-2.78%)	⬇️
pkg/xds/generator/direct_access_proxy_generator.go	89.65% <0.00%> (-1.15%)	⬇️
pkg/plugins/resources/postgres/store.go	76.37% <0.00%> (-0.43%)	⬇️
pkg/core/resources/manager/cache.go	88.31% <0.00%> (+2.59%)	⬆️
pkg/core/runtime/component/component.go	92.98% <0.00%> (+3.50%)	⬆️
... and 3 more

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[lahabana]

Is there no way to make it do the right thing? Figure out if v6 is enabled and use v4 otherwise fallback to v6.
My problem with this is that it's yet another magical config users will need to set and by default the behaviour isn't great

[slonka]

Is there no way to make it do the right thing? Figure out if v6 is enabled and use v4 otherwise fallback to v6.

Just so I'm 100% getting this right: you want to resolve the address in kuma-dp, check if ipv6 is available, if not fallback to ipv4, and then set the appropriate setting in Envoy?

[lahabana]

Yes it's something that was done there for a similar problem: #3403

Actually should the bootstrap template use the configurers in pkg/xds/envoy/clusters/configurers? It seems to me that we rebuild the whole envoy conf from scratch when we've spent time at making good helpers in pkg/xds/envoy WDYT @jakubdyszkiewicz ?

[slonka]

We picked this #4275 over this approach.