CCM: watch-based route controller reconciliation using informers

[lukasmetzner]

Enhancement Description

The cloud-controller-manager includes several controllers, one of which is the routes controller. Currently, this controller reconciles cloud routes at a fixed interval (default: 10 seconds), resulting in unnecessary API calls to cloud providers.

In contrast, other controllers like the service and node controllers have already adopted a more efficient watch-based approach using informers.

This enhancement proposes introducing a new feature gate in the cloud-controller-manager to enable an informer-based reconciliation mechanism for the routes controller, reducing redundant API traffic and improving efficiency.

• One-line enhancement description (can be used as a release note): Introduce watch-based reconciliation in the cloud-controller-managers route controller
• Kubernetes Enhancement Proposal: TBD
• Discussion Link: meeting notes
• Primary contact (assignee): @lukasmetzner @apricote
• Responsible SIGs: cloud-provider
• Enhancement target (which target equals to which milestone):
  • Alpha release target (x.y): 1.34
  • Beta release target (x.y): 1.35
  • Stable release target (x.y): 1.36
• Alpha
  • KEP (k/enhancements) update PR(s):
  • Code (k/k) update PR(s): WIP: feat(ccm): watch-based route controller reconciliation kubernetes#131220
  • Docs (k/website) update PR(s):

[lukasmetzner]

/sig cloud-provider

[aojea]

I personally do not think we need a KEP for this, we have made this sort of changes on the past in this area and is how we implement all of our controllers, so this is more about cleaning tech debt.

I'm happy to help with the review since the change seems relatively simple, but I leave the final decision to cloud provider leads @cheftako @elmiko WDYT?

[lukasmetzner]

I have brought this to the sig/cloud-provider meeting and the decision was to create a KEP. The meeting is unfortunetly not yet uploaded, so I have added a link to the meeting notes for now.

Not everyone was present in the meeting, maybe we want to discuss this here?

It is my first contribution, so I am unopinionated if this should have a KEP ^^