Automatic merge from submit-queue (batch tested with PRs 40796, 40878, 36033, 40838, 41210)
StatefulSet hardening
**What this PR does / why we need it**:
This PR contains the following changes to StatefulSet. Only one change effects the semantics of how the controller operates (This is described in #38418), and this change only brings the controller into conformance with its documented behavior.
1. pcb and pcb controller are removed and their functionality is encapsulated in StatefulPodControlInterface. This class modules the design contoller.PodControlInterface and provides an abstraction to clientset.Interface which is useful for testing purposes.
2. IdentityMappers has been removed to clarify what properties of a Pod are mutated by the controller. All mutations are performed in the UpdateStatefulPod method of the StatefulPodControlInterface.
3. The statefulSetIterator and petQueue classes are removed. These classes sorted Pods by CreationTimestamp. This is brittle and not resilient to clock skew. The current control loop, which implements the same logic, is in stateful_set_control.go. The Pods are now sorted and considered by their ordinal indices, as is outlined in the documentation.
4. StatefulSetController now checks to see if the Pods matching a StatefulSet's Selector also match the Name of the StatefulSet. This will make the controller resilient to overlapping, and will be enhanced by the addition of ControllerRefs.
5. The total lines of production code have been reduced, and the total number of unit tests has been increased. All new code has 100% unit coverage giving the module 83% coverage. Tests for StatefulSetController have been added, but it is not practical to achieve greater coverage in unit testing for this code (the e2e tests for StatefulSet cover these areas).
6. Issue #38418 is fixed in that StaefulSet will ensure that all Pods that are predecessors of another Pod are Running and Ready prior to launching a new Pod. This removes the potential for deadlock when a Pod needs to be rescheduled while its predecessor is hung in Pending or Initializing.
7. All reference to pet have been removed from the code and comments.
**Which issue this PR fixes**
fixes #38418,#36859
**Special notes for your reviewer**:
**Release note**:
```release-note
Fixes issue #38418 which, under circumstance, could cause StatefulSet to deadlock.
Mediates issue #36859. StatefulSet only acts on Pods whose identity matches the StatefulSet, providing a partial mediation for overlapping controllers.
```
1. pcb and pcb controller are removed and their functionality is
encapsulated in StatefulPodControlInterface.
2. IdentityMappers has been removed to clarify what properties of a Pod are
mutated by the controller. All mutations are performed in the
UpdateStatefulPod method of the StatefulPodControlInterface.
3. The statefulSetIterator and petQueue classes are removed. These classes
sorted Pods by CreationTimestamp. This is brittle and not resilient to
clock skew. The current control loop, which implements the same logic,
is in stateful_set_control.go. The Pods are now sorted and considered by
their ordinal indices, as is outlined in the documentation.
4. StatefulSetController now checks to see if the Pods matching a
StatefulSet's Selector also match the Name of the StatefulSet. This will
make the controller resilient to overlapping, and will be enhanced by
the addition of ControllerRefs.
Test containers need to run as spc_t in order to interact with the host
filesystem under /tmp, as the tests for StatefulSet are doing. Docker
will transition the container into this domain when running the container
as privileged.
Signed-off-by: Steve Kuznetsov <skuznets@redhat.com>
