A Kubernetes Node requires to have at minimum one IP address
because those are used on the Pods field HostIPs and in some cases,
when pods uses hostNetwork: true, as PodIPs.
Nodes that use IP addresses as Hostname are interpreted as an IP
address, so it is possible that are nodes that don't hane any DNSname.
The feature gate AllowDNSOnlyNodeCSR will allow user to opt-in for
the old behavior.
Change-Id: I094531d87246f1e7a5ef4fe57bd5d9840cb1375d
MultiCIDRServiceAllocator implements a new ClusterIP allocator based on
IPAddress object to solve the problems and limitations caused by
existing bitmap allocators.
However, during the rollout of new versions, deployments need to support
a skew of one version between kube-apiservers. To avoid the possible
problem where there are multiple Services requests on the skewed
apiservers and that both allocate the same IP to different Services,
the new allocator will implement a dual-write strategy under the
feature gate DisableAllocatorDualWrite.
After the MultiCIDRServiceAllocator is GA, the DisableAllocatorDualWrite
can be enabled safely as all apiservers will run with the new
allocators. The graduation of DisableAllocatorDualWrite can also
be used to clean up the opaque API object that contains the old bitmaps.
If MultiCIDRServiceAllocator is enabled and DisableAllocatorDualWrite is disable
and is a new environment, there is no bitmap object created, hence, the
apiserver will initialize it to be able to write on it.
* Add `Linux{Sandbox,Container}SecurityContext.SupplementalGroupsPolicy` and `ContainerStatus.user` in cri-api
* Add `PodSecurityContext.SupplementalGroupsPolicy`, `ContainerStatus.User` and its featuregate
* Implement DropDisabledPodFields for PodSecurityContext.SupplementalGroupsPolicy and ContainerStatus.User fields
* Implement kubelet so to wire between SecurityContext.SupplementalGroupsPolicy/ContainerStatus.User and cri-api in kubelet
* Clarify `SupplementalGroupsPolicy` is an OS depdendent field.
* Make `ContainerStatus.User` is initially attached user identity to the first process in the ContainerStatus
It is because, the process identity can be dynamic if the initially attached identity
has enough privilege calling setuid/setgid/setgroups syscalls in Linux.
* Rewording suggestion applied
* Add TODO comment for updating SupplementalGroupsPolicy default value in v1.34
* Added validations for SupplementalGroupsPolicy and ContainerUser
* No need featuregate check in validation when adding new field with no default value
* fix typo: identitiy -> identity
