The intent is to catch abnormal runtimes with the generously large default
timeout of 10 seconds.
We have to set up a context with the configured timeout (optional!), then
ensure that both CEL evaluation and the allocation logic itself properly
returns the context error. The scheduler plugin then can convert that into
"unschedulable".
The allocator and thus Filter now also check for context cancellation by the
scheduler. This happens when enough nodes have been found.
Initializing the scheduler Features struct will be needed in different places,
therefore NewSchedulerFeaturesFromGates gets introduced. Besides, having it
next to the struct makes it easier to add new features.
The DRASchedulerFilterTimeout feature gate simplifies disabling the timeout
because setting a feature gate is often easier than modifying the scheduler
configuration with a zero timeout value.
The timeout and feature gate are new. The gate starts as beta and enabled by
default, which is consistent with the "smaller changes with low enough risk
that still may need to be disabled..." guideline.
When using context.CancelCause in the scheduler and context.Cause in plugins,
the status returned by plugins is more informative than just "context
canceled".
Context cancellation itself is not new, but many plugin authors probably
weren't aware of it because it wasn't documented.
The goal is to maintain different version of the allocator logic. We already
had one incidence where adding an alpha feature caused a regression also when
it was disabled. Not everything can be implemented within obviously correct if
branches.
This also opens the door for implementing different alternatives.
The code just gets moved around for now.
* Move ClusterEvent type to staging repo, leaving some functions (that contain logic internal to scheduler) in kubernetes/kubernetes
apply review comment and fix linter warning
* update-vendor.sh
* update doc comments
* run update-vendor.sh
The current behavior is to select only based on pod priority, where any
pod with higher priority can preempt any pod with lower priority.
In our case, we have multiple priority classes but where only a subset
of those are considered preemptible. Here's roughly how this looks:
- High priority: higher in the scheduling queue, not preemptible
- Low priority: lower in the scheduling queue, not preemptible
- Preemptible priority: lowest in the scheduling queue, preemptible
This PR allows the preemption selection to be configured against the
`DefaultPreemption` plugin, rather than needing to reimplement the
plugin itself. The structure used here mimics [what's currently being
done for the `Evaluator`](https://github.com/kubernetes/kubernetes/blob/release-1.32/pkg/scheduler/framework/preemption/preemption.go#L161-L165),
where a `PreemptPod` callback may be overridden to customize what
happens when performing a preemption.
This PR also updates the plugin's tests to call the updated `New()`
function rather than constructing `DefaultPreemption` directly, so
that `New()` is now being exercised in tests.
