Automatic merge from submit-queue
Kubelet: implement GetNetNS for new runtime api
Kubelet: implement GetNetNS for new runtime api.
CC @yujuhong @thockin @kubernetes/sig-node @kubernetes/sig-rktnetes
New flag --container-runtime-endpoint (overrides --container-runtime)
is introduced to kubelet which identifies the unix socket file of
the remote runtime service. And new flag --image-service-endpoint is
introduced to kubelet which identifies the unix socket file of the
image service.