Implement, in the endpoint slice controller, the same logic
used for labels in the legacy endpoints controller.
The labels in the endpoint and in the parent must be equivalent.
Headless services add the well-known IsHeadlessService label.
Slices must have two well known labels: LabelServiceName and
LabelManagedBy.
Previously the controllers would proceed with additional creates,
updates, or deletes if 1 failed. That could potentially result in
scenarios where an EndpointSlice create or update failing while a delete
worked. This updates the logic so that removals will not happen if
additions fail.
EndpointController was accidentally requiring all headless services to
be IPv4-only in clusters with IPv6DualStack enabled.
This still leaves "legacy" (ie, IPFamily-less) headless services as
always IPv4-only because the controller doesn't currently have easy
access to the information that would allow it to fix that.
(EndpointSliceController had the same problem already, and still
does.) This can be fixed, if needed, by manually setting IPFamily,
and the proposed API for 1.20 will handle this situation better.
During EndpointSlice reconcilation, EndpointSliceTracker is supposed to
track expected EndpointSlice resource versions so that external changes
to them can be detected. But it actually tracked the stale resource
version and resulted in every Service was handled twice as it always
received an EndpointSlice update with a different resource version but
was actually created/updated by itself during the first processing.
This adds a new EndpointSlice tracker to keep track of the expected resource versions of EndpointSlices associated with each Service managed by the EndpointSlice controller. This should prevent a potential race where a syncService call could happen with an incomplete view of EndpointSlices if additions or deletions hadn't fully propagated to the cache yet. Additionally, this ensures that external changes to EndpointSlices will be handled by the EndpointSlice controller.
This was an oversight in the initial EndpointSlice release. This update
will ensure that Endpoints and EndpointSlices use the same logic to set
the Hostname attribute.
The Service spec includes a PublishNotReadyAddresses field which has
been used by Endpoints to report all matching resources ready. This may
or may not have been the initial purpose of the field, but given the
desire to provide backwards compatibility with the Endpoints API here,
it seems to make sense to continue to provide the same functionality.
