[Beta: 1.31] Consistent Reads from Cache

[shekhar-rajak]

Enhancement Description

• One-line enhancement description : Consistent Reads from Cache
• Kubernetes Enhancement Proposal:

Kubernetes Get and List requests are guaranteed to be "consistent reads" if the resourceVersion parameter is not provided. Consistent reads are served from etcd using a "quorum read".

But often the watch cache contains sufficiently up-to-date data to serve the read request, and could serve it far more efficiently.

This KEP proposes a mechanism to serve most reads from the watch cache while still providing the same consistency guarantees as serving the read from etcd.

• Discussion Link:
• KEP link: https://github.com/kubernetes/enhancements/blob/master/keps/sig-api-machinery/2340-Consistent-reads-from-cache/README.md
• Primary contact (assignee): @serathius
• Responsible SIGs: sig-api-machinery
• Enhancement target (which target equals to which milestone):
  • [x] Alpha 1.28
    • [x] KEP (k/enhancements) update PR(s):
      • https://github.com/kubernetes/enhancements/pull/4047
    • [x] Code (k/k) update PR(s): https://github.com/kubernetes/kubernetes/pull/118508
    • [x] Docs (k/website) update PR(s): https://github.com/kubernetes/website/pull/42083
    • [x] Scalability tests: https://github.com/kubernetes/test-infra/pull/30094
  • [x] Beta 1.31
    • [x] KEP (k/enhancements) update PR(s):
      • https://github.com/kubernetes/enhancements/pull/4134
    • [x] Code (k/k) update PR(s):
      • https://github.com/kubernetes/kubernetes/pull/125115
      • https://github.com/kubernetes/kubernetes/pull/124612(previous https://github.com/kubernetes/kubernetes/pull/123264)
      • https://github.com/kubernetes/kubernetes/pull/124483
      • https://github.com/kubernetes/kubernetes/pull/123513

### Tasks
- [x] https://github.com/kubernetes/perf-tests/issues/2540
- [ ] https://github.com/kubernetes/kubernetes/issues/123185
- [ ] https://github.com/kubernetes/kubernetes/issues/123187
- [ ] https://github.com/kubernetes/kubernetes/issues/123192
- [ ] https://github.com/kubernetes/kubernetes/pull/123513