kubernetes-sigs / lws / 30464365376

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github

Committed by web-flow

Commit Message

feat(disaggregatedset): per-role autoscaling via DisaggregatedSetRoleScaler (#922)

* feat(disaggregatedset): per-role autoscaling via DisaggregatedSetRoleScaler

Adds KEP-849 alpha implementation of per-role external scaling for
DisaggregatedSet. A role opts in via scaling.mode: External; the DS
controller then auto-creates a DisaggregatedSetRoleScaler named
"<ds>-<role>" that exposes /scale for HPA, KEDA, or any /scale-aware
controller. Replicas flow: autoscaler → scaler.spec.replicas → LWS.

New CRD DisaggregatedSetRoleScaler with the /scale subresource, aggregate
status.selector across revisions, and controller ownerRef for GC. The
executor resolves per-role targets from the scaler map; a no-shrink guard
prevents the new-revision target from shrinking mid-rollout if HPA writes a
smaller value. Webhook warns on External + spec.replicas > 1 and rejects
External + spec.slices > 1 (alpha restriction).

* test(disaggregatedset): e2e regression guard for /scale on a fresh scaler

Adds test/e2e/disaggregatedset/hpa_test.go covering three invariants that
unit tests can't reach because they need a real apiserver in the loop:

  1. GET /scale on a freshly auto-created scaler must return 200. This is
     the regression guard for yankay/lws#15 — HPA reads /scale before its
     first write, and if the CRD scale handler errors because .spec.replicas
     is missing, HPA parks in AbleToScale=False / FailedGetScale forever.
  2. kubectl scale on the scaler propagates spec.replicas to the underlying
     LWS (guards controller wiring end-to-end).
  3. Deleting the parent DS garbage-collects the auto-created scaler via
     the controller ownerRef (fake client doesn't model GC).

Extends test/testutils/disaggregatedset/fixtures.Role with an External bool
that emits scaling.mode: External on the role.

Spec #1 currently fails on this branch as expected — spec.replicas is a
*int32 that stays nil on auto-created scalers, and the apiserver's scale
handler cannot extr... (continued)

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190 of 240 new or added lines in 4 files covered. (79.17%)

114 existing lines in 3 files now uncovered.

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