Support new kubernetes resource EndpointsSlice

[howardjohn]

https://github.com/kubernetes/enhancements/blob/master/keps/sig-network/20190603-EndpointSlice-API.md adds a new API to Kubernetes. It has a lot of overlap with our ServiceEntry. It seems plausible that we could completely remove ServiceEntry in favor of the new API.

At the very least, we will need to update Pilot/Galley to understand EndpointSlices

Actions:

• Initial support: Initial support for endpoint slice #18394
• Improve unit test coverage - run all tests with endpoints and slices: Test both endpoints and slices for unit tests #19645
• Improve e2e coverage
• Add a mode where both endpoints and slices are read
• Do not read nodes if just using slice
• Do not require pod reading if just using slice? Needs more stuff put into the slices like SA
• Documentation
• Replace/add Endpoint Slice in place of STATIC service entry in tests/docs/users usage
• Investigate backporting endpoint slice as a CRD to old clusters

[howardjohn]

Test using kind:

kind: Cluster
apiVersion: kind.sigs.k8s.io/v1alpha3
kubeadmConfigPatches:
- |
  apiVersion: kubeadm.k8s.io/v1beta2
  kind: ClusterConfiguration
  metadata:
    name: config
  apiServer:
    extraArgs:
      "feature-gates": "EndpointSlice=true"
      "runtime-config": "discovery.k8s.io/v1alpha1=true"
  controllerManager:
    extraArgs:
      "controllers": "*,-endpoint,endpointslice"

kind create cluster --image aojea/kindnode:latest --config config.yaml (there is not official 1.16 node image yet, config.yaml refers to above)

[hzxuzhonghu]

@howardjohn EndpointsSlice is to replace Endpoints, it is 1:n relation for service and endpointslices , so it is a little complicated to support it. In k8s 1.16 it is an alpha feature, so maybe in 1.17 or 1.18, it can be beta.

BTW, kube-proxy is a good example to understand EndpointSlices.

[howardjohn]

It seems we also cannot use EndpointSlice until we update client-go. We cannot update client-go to 1.16, because then we lose support for things that were removed in 1.16. And additionally, we depend on other libraries that refuse to upgrade to 1.16 for the same reason... not sure what we can do here.

[bowei]

cc: @freehan @robscott

[howardjohn]

status update: blocked by #17831, which shouldn't be too much work to get working. Once we have that done, I have a WIP that is probably 80% done for base level support. To actually do similar splicing in Envoy is much more work and dependent on some Envoy side changes

[howardjohn]

I am about 80% done with this in https://github.com/istio/istio/pull/18394/files, just need to fix a few tests and clean things up I think

[istio-policy-bot]

🧭 This issue or pull request has been automatically marked as stale because it has not had activity from an Istio team member since 2019-11-27. It will be closed on 2020-03-11 unless an Istio team member takes action. Please see this wiki page for more information. Thank you for your contributions.

Created by the issue and PR lifecycle manager.

[chihaiaalex]

Hello. From which version does Istio support the new EndpointSlice resource?