PLT-2119: Replace per-tag PSLs with single tag-agnostic PrometheusServiceLevel#620
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PLT-2119: Replace per-tag PSLs with single tag-agnostic PrometheusServiceLevel#620eddiebarth1 wants to merge 4 commits into
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eddiebarth1
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Jun 9, 2026
…viceLevel
Every deploy created a per-tag PSL ({app}-{target}-{tag}-servicelevels);
Sloth regenerates burn-rate rules on any PSL change, so each deploy reset
burn-rate windows and emitted duplicate alert series per revision.
- One stable PSL per app/target ({app}-{target}-servicelevels); the name
comes from one helper shared by the sync and delete paths.
- SLI queries preserve per-revision granularity: sum by (tag) (rate(...))
replaces the per-tag sum(rate(...{tag=X})). Verified numerically
identical per tag against prod Thanos.
- Single writer, modeled on syncSLORules: ResourceSyncer.syncServiceLevels
upserts while the leading releasable revision has enabled SLOs, deletes
otherwise. Steady state never writes (CreateOrUpdate no-ops on identical
specs); the PSL only changes when SLO definitions change.
- Teardown deletes the shared PSL before the ReleaseManager self-deletes.
Unlike namespace-scoped service-wide objects, the PSL lives in the
cross-app service-levels namespace where neither namespace cascade nor
cross-namespace OwnerReferences can reach it.
- DeleteServiceLevels deletes by deterministic name; the old LabelTag=""
selector never matched an absent label (silent no-op).
- Enabled=false is filtered once at the source (prepareServiceLevelObjectives)
so PSL, SLO rules, and ServiceMonitors uniformly stop observing.
- Legacy per-tag PSLs are scrubbed per-incarnation via
deleteTaggedServiceLevels; SyncTaggedServiceLevels and its helpers are
removed as dead code.
- Tests: plan-level sync/delete units plus controller-level coverage for
prepareServiceLevelObjectives filtering, the sync-vs-delete decision,
and a teardown regression test.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Codify the scope model from Sofie's review: syncer.go owns app/target-lifetime objects, incarnation.go and state handlers own per-revision objects, and shared-resource cleanup requires visibility of the full incarnation collection (PICCHU-INV-SCOPE-1/2/3). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Per Sofie's review: - serviceLevelIndicator.tagKey lets a service expose its revision under a label other than "tag" (kbfd defaults it to "tag"; no service overrides it today). The shared SLI source now label_replace's a custom tagKey into the canonical "tag" label so Sloth recording rules and burn-rate alerts keep the label the rollback pipeline matches on, preserving the adjustability the old per-tag queries had. Covered by a fixture SLO using tagKey: destination_workload. - Restore the skip log when service-levels-namespace is unset, matching the old syncTaggedServiceLevels behavior. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
…review
- SyncServiceLevels now mirrors the original SyncTaggedServiceLevels
structure exactly: list-shaped builder with (value, error) return,
Enabled checked in the plan, name built by a serviceLevelName method.
- DeleteServiceLevels returns to the list/selector form. The only change
from the original is dropping LabelTag:"" from the selector - equality
selectors never match an absent label, which made the old delete a
silent no-op. The {app, target} selector also sweeps lingering legacy
per-tag PSLs once observation is off; test covers shared + legacy
deletion and other-app isolation.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Closes PLT-2119
Why
Every deploy created a per-tag PSL (
{app}-{target}-{tag}-servicelevels). Sloth regenerates burn-rate rules whenever a PSL changes, so every deploy reset the burn-rate windows and emitted a fresh alert series per revision — noisy duplicate SLO alerts, untrustworthy burn-rate trends.What
{app}-{target}-servicelevels), built bySyncServiceLevelsmirroring the structure of the originalSyncTaggedServiceLevels.sum by (tag) (rate(...))replaces the per-tagsum(rate(...{tag="X"})). Numerically identical per tag (verified below).ResourceSyncer.syncServiceLevelsupserts when the leading releasable revision has enabled SLOs, deletes otherwise. Steady state never writes —CreateOrUpdateno-ops on identical specs, so the PSL only changes when SLO definitions change (rare, and the one case where windows still reset, since the rules genuinely changed).DeleteServiceLevelskeeps the list/selector form, minus the bug. The old selector includedLabelTag: "", which never matches an absent label — cleanup was a silent no-op. The selector is now{app, target}, which matches the shared PSL and also sweeps any lingering legacy per-tag PSLs once observation is off.serviceLevelIndicator.tagKey. No service overrides it today (kbfd defaults it totag), but a custom key (e.g.destination_workload) islabel_replace'd into the canonicaltaglabel so the rollback pipeline keeps matching.PICCHU-INV-SCOPE-*invariants in CLAUDE.md, so the lesson outlives this PR.Behavior changes
Enabled: falsenow also removes the SLO's recording rules and ServiceMonitor (previously only the PSL honored it). Disabled uniformly means "do not observe".IsRevisionTriggeredmatches picchu's own per-tag canary rules (canary="true"/slo="true"—syncCanaryRules, not in this diff). The PSL feeds human burn-rate alerting only.Verified against prod Thanos (2026-06-09, pre-ship)
{app}:{slo}:errors|total, e.g.medium2:authentication_account_login_success:total) carrytagon all 4 production clusters.max without (sloth_window)→tagsurvives into firing alerts.tag: only clientele (aggregates bysource_canonical_revision) and drizzle (metric has notaglabel) — both already have no per-revision SLI today; not regressions. Nois_grpcSLOs exist fleet-wide.Test plan
make test/make fmt vet; unit tests for the lifecycle (Enabled filtering, sync-vs-delete decision, teardown deletes the PSL before RM self-delete)sloth_id(values are identical; watch prometheus-slo for duplicate-sample warnings until scrub completes)Enabled: falseflip removes rules + ServiceMonitor; decommission deletes the shared PSL🤖 Generated with Claude Code