feat(loadbalancer): Add LoadBalancerType Client Side Weighted Round Robin

[altaiezior]

What type of PR is this?

What this PR does / why we need it:
This PR provides addition of new load balancer type client side weighted round robin. This is a new load balancing extension introduced since envoy 1.32

https://www.envoyproxy.io/docs/envoy/latest/api-v3/extensions/load_balancing_policies/client_side_weighted_round_robin/v3/client_side_weighted_round_robin.proto

Which issue(s) this PR fixes:

Fixes #7305

Release Notes: Yes

[altaiezior]

@jukie I have added the implementation and also tested it on my local setup

PS: the repo is so easy to contribute everything just works with the docs given on the site :)

[altaiezior]

Also I wanted to know should I include slow start in client wrr?

So the thing is that I have submitted the proposal in grpc-xds grpc/proposal#498 and also in envoy I have got the proto updated.

It is not implemented yet, but I am trying to pick it up this month if my time allows

[altaiezior]

Also I am unsure of how to test this e2e, so I have just included an AI generated e2e test suite.

The challenge here is that we need multiple replicas with each server respond with a specific header containing rps and cpu_utilisation and then the traffic is distributed by calculating the weight (rps / cpu)

I don't know what the current e2e tests allow and if this type of test case is feasible to write

[codecov]

Codecov Report

❌ Patch coverage is 68.53933% with 28 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.32%. Comparing base (1005160) to head (b570798).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/xds/translator/cluster.go	58.53%	16 Missing and 1 partial ⚠️
internal/gatewayapi/clustersettings.go	75.00%	4 Missing and 4 partials ⚠️
internal/gatewayapi/backendtrafficpolicy.go	75.00%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7407      +/-   ##
==========================================
- Coverage   74.34%   74.32%   -0.03%     
==========================================
  Files         242      242              
  Lines       37707    37793      +86     
==========================================
+ Hits        28035    28089      +54     
- Misses       7730     7754      +24     
- Partials     1942     1950       +8     

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[altaiezior]

Also I wanted to know should I include slow start in client wrr?

So the thing is that I have submitted the proposal in grpc-xds grpc/proposal#498 and also in envoy I have got the proto updated.

It is not implemented yet, but I am trying to pick it up this month if my time allows

I have started the implementation of slow_start_config and locality lb config with WRR as well, if possible I would also want to include them in the gatway implementation.

envoyproxy/envoy#41841

[jukie]

We wait to add features here until they've made it into a full envoy release. The flow would be getting this lb support added for 1.7 and if your envoy changes get merged we can add that support to gateway in 1.8.

Let's keep the scope of this PR to what's currently available and we can always include additional features in a follow-up. Are you able to make the suggested changes or can you join the contributors call next week to discuss?

[altaiezior]

Sure, I just paused because the other changes were also approved, but I understand I will make the respective changes as suggested. Will try to complete them by today / tomorrow @jukie

[altaiezior]

@jukie I have made the respective changes

[jukie]

Overall looks good, just a few more comments @anuragagarwal561994! Thanks for adding this and make sure to run gen-check before pushing.

Sorry for the delayed review on this. I'll prioritize helping you with this next week.

[altaiezior]

@jukie I will be able to pick up these changes only by next week as I am travelling and been catching up with my work lately.

[jukie]

@altaiezior do you still plan on updating this?

[altaiezior]

@jukie I want to but the conflicts are a bit much and I am currently caught up with my work, so I will need more time to look into this.

[altaiezior]

@jukie I have re-merged master now with this branch, most of the merge-conflicts I have resolved with the help of AI and reviewed it once on my own.

[altaiezior]

@jukie do I need to make some changes here?

[jukie]

@altaiezior just a few nits left. I'd really like to see this make it into 1.8 and will make it a priority to review if you're able to add the changes.

[altaiezior]

Yey :)