feat: add nodeselector annotation to limit LB pool members

[mweibel]

Adds the possibility to limit a LoadBalancer created using a Service to only a specific set of nodes.

Notes for reviewers:
If you come up with a better way to check the LB actually switched to the intended pool member number please let me know. It's a bit ugly having to fetch the members from the API directly. However, I can't verify it using the service alone because while the LoadBalancer members are adjusting, no change is made to the service. This in itself might be something we need to consider, however IIRC we can't know this at the moment due to missing information in the API.

[alakae]

If you come up with a better way to check the LB actually switched to the intended pool member number please let me know. It's a bit ugly having to fetch the members from the API directly. However, I can't verify it using the service alone because while the LoadBalancer members are adjusting, no change is made to the service. This in itself might be something we need to consider, however IIRC we can't know this at the moment due to missing information in the API.

I think it is fine. I was just thinking that maybe we could generate events for each API component that is created/deleted and assert these events? But I would actually consider this an improvement on top of directly checking the API.

[mweibel]

If you come up with a better way to check the LB actually switched to the intended pool member number please let me know. It's a bit ugly having to fetch the members from the API directly. However, I can't verify it using the service alone because while the LoadBalancer members are adjusting, no change is made to the service. This in itself might be something we need to consider, however IIRC we can't know this at the moment due to missing information in the API.

I think it is fine. I was just thinking that maybe we could generate events for each API component that is created/deleted and assert these events? But I would actually consider this an improvement on top of directly checking the API.

let's talk about this offline - I wonder if it would generate too much events but maybe I'm misinterpreting what you mean exactly.