fix: Alert when TPP edge apply lag exceeds 30s - #337
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Measured upstream→edge TPP generation convergence is ~1.5s in staging and ~3.3s in prod. Adopt a 30s SLO (~10x headroom) and alert when cache generation stays ahead of applied generation on an edge. Key features: - TrafficProtectionPolicyApplyLagSLOViolation on nso_extension_tpp_* generation gauges, aggregated per cluster/policy - promtool coverage for lag, in-sync, and brief-skew cases Related to #266.
ecv
approved these changes
Aug 6, 2026
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Summary
Second point on #266 asked us to measure upstream→edge TrafficProtectionPolicy propagation and decide whether it needs an SLO. Generation-bump samples converge in ~1.5s on staging and ~3.3s on prod — well under a 30s budget — so this adopts that SLO and pages when an edge stays behind.
The alert watches the existing extension-server gauges (
nso_extension_tpp_cache_generationvsnso_extension_tpp_applied_generation), aggregated per edge/policy so replica noise does not flap.nowaf-testhelp-d9c5g5portfolio-lmpn0uwaf-test-3gsu2vTest plan
promtool test rulesontest/prometheus-rules/gateways/nso-slo-tests.yaml(lag / in-sync / brief-skew)envoy-gateway-extension-servermetrics (same path as TLS extension alerts)cache > appliedis empty today)Related to #266.