Implement LoadBalancerSourceRanges for UDP

[aojea]

          maybe fixed, but only for TCP because I couldn't figure out for sure where to add it for UDP

Originally posted by @danwinship in #80 (comment)

This require some knowledge of envoy, as a guidance people can use the linked PR above

[danwinship]

Note that whoever implements this probably needs to add an e2e test to kubernetes for it too 🙂

[THUzxj]

Hi, I'd like to work on this. As far as I understand, I should add source_prefix_ranges (or templates with the same function) to the UDP branch of proxyLDSConfigTemplate, and the tests of UDP are very similar to those of TCP (just replace TCP with UDP). Please figure out if I misunderstand.
However, I am unclear on how to run the e2e test in the Kubernetes repo with cloud-provider-kind. I'd appreciate it if you could give me some instructions.

[aojea]

This script can serve you as guide to run the e2e tests https://github.com/kubernetes-sigs/cloud-provider-kind/blob/main/hack/ci/e2e.sh and more info in kubernetes-sigs/kind#1181 (comment)

[danwinship]

As far as I understand, I should add source_prefix_ranges (or templates with the same function) to the UDP branch of proxyLDSConfigTemplate

It's been a while since I looked at this, but IIRC, there was no obvious way to just copy the approach we used for TCP into the UDP config. The right options didn't seem to be available? You'll probably have to dig into the envoy documentation a bit...