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/No

[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 72.85714% with 19 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.89%. Comparing base (fc43a31) to head (6321ec4).
⚠️ Report is 1 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	92.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7407      +/-   ##
==========================================
+ Coverage   72.85%   72.89%   +0.04%     
==========================================
  Files         237      237              
  Lines       35623    35690      +67     
==========================================
+ Hits        25952    26017      +65     
- Misses       7824     7827       +3     
+ Partials     1847     1846       -1     

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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.

[github-actions]

This pull request has been automatically marked as stale because it has not had activity in the last 30 days. Please feel free to give a status update now, ping for review, when it's ready. Thank you for your contributions!

[altaiezior]

@jukie can you help me resolve the changes I need to make with the above MR to make it releasable, I was on vacation for a while. I am back now and can work upon them

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[jukie]

This is in a pretty good state, thanks @anuragagarwal561994! If you'd like some help building the e2e or want to brainstorm feel free to DM in the envoy slack.

[altaiezior]

This is in a pretty good state, thanks @anuragagarwal561994! If you'd like some help building the e2e or want to brainstorm feel free to DM in the envoy slack.

I already have a e2e setup on my local that I had built with earlier changes using AI, I would need to do some modifications in it after the new changes and make it ready to be published in my repo, because I am currently using an internal library we built to consistently publish the server metrics across applications.

[arkodg]

can we test the feature in the e2e ? i.e. have the backend craft a endpoint-load-metrics response header and use that in LB decision making

[altaiezior]

@arkodg this we have discussed in earlier comment that it will take some time to build and can be done seaprately because this requires changes with the current echo application too.

#7407 (comment)