To make it easier for out-of-tree developers to import the scheduler framework, among other scheduling helpers and constants, we should explore areas that we can remove dependencies on k8s.io/kubernetes. Places that could be easily removed are, for example, using internal APIs where not required or importing unrelated packages for simple helpers which can be trivially implemented. This will clean up the dependency tree for importing scheduler code externally.

This is related to: Proposal to migrate scheduler code to staging. While the proposal includes all scheduler code, we are only focusing on scheduler framework code. However identifying anywhere in the scheduler code that these dependencies can be cleaned up will be helpful as well.

This will probably be an ongoing cleanup effort, and breaking the work into smaller PRs may actually help with review and preventing code breaking in the process.
/kind cleanup
/sig scheduling

PRs opened so far:

• Scheduler: remove pkg/apis/core/field_constants.go #90105 pkg/apis/core @xiaoanyunfei
  • moving the default scheduler name and references to the external api
• Scheduler: remove direct import to /pkg/api/core/v1/helper Part 1 #90006 pkg/api/core/v1/helper @gavinfish (part 1)
  • copies GetPersistentVolumeClaimClass, which is used in several other areas around pkg/volume
  • replaced by Move GetPersistentVolumeClaimClass to component-helpers #98433
• Scheduler: remove dependency on pkg/apis/core/v1/helper #91782 Overview issue of pkg/api/core/v1/helper @ingvagabund
• Scheduler:remove direct dependency for pkg/api/testing #90041 pkg/api/testing @tanjunchen
• Moving a dependency on pkg/api/v1/pod and switching to component-helper #90039 pkg/scheduler/util pkg/api/v1/pod @yuzhiquan 🔹
  • move GetPodPriority to scheduler utils
  • scheduler: remove import pkg/api/v1/pod.GetPodPriority #90703 pkg/api/v1/pod @yiyang5055 🔹
• Scheduler:remove direct dependency for k8s.io/kubernetes/pkg/controller/volume/scheduling/metrics #90046 pkg/controller/volume/scheduling/metrics @tanjunchen
  • copies metrics registration and definitions around volume binding
• Scheduler: remove direct import to /pkg/features #90111 pkg/features @gavinfish 🔹
  • held on How to deal with feature gates for staging components #90136 discussion on feature gating for staging components
• scheduler: remove direct import to pkg/master/ports #90000 pkg/master/ports @SataQiu
• Scheduler:remove direct dependency for k8s.io/kubernetes/pkg/util/node and remove // TODO: prefer stable labels for zone in v1.18 #90040 pkg/util/node @tanjunchen 🔹
  • copies Node util GetZoneKey, which should be moved to external and imported by both
  • replaced by Scheduler: remove direct dependency for k8s.io/kubernetes/pkg/util/node #97818
• Scheduler: remove direct import to /pkg/util/parsers #90008 pkg/util/parsers @gavinfish
  • removes DefaultImageTag (":latest") const only used by us and kubelet
• Scheduler: remove direct import to /pkg/volume/util #90007 pkg/volume/util @gavinfish
  • still have dependency on VolumeBinder

🔹 = Adds code to pkg/scheduler/util, which should be externalized