hub: optional startupProbe for slow-startup migration windows#44
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Adds an optional hub.startupProbe (disabled by default to preserve existing behaviour). When enabled, kubelet gives Hub the full failureThreshold × periodSeconds window to become Ready before the liveness and readiness probes start counting failures. Default tuning when enabled is 30 × 5s = 150s. Useful on a cold start where Hub takes longer than the existing liveness probe's tolerance (default 15s, periodSeconds=5 × failureThreshold=3) — for example when Hub has to run a substantial Postgres schema migration as part of an upgrade. Without this probe, large migrations risk being interrupted mid-flight by kubelet restarting the pod. Backward compatible: existing installs see no change unless they explicitly set hub.startupProbe.enabled=true.
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Summary
Adds an optional
hub.startupProbe(disabled by default to preserve existing behaviour). When enabled, kubelet gives Hub the fullfailureThreshold × periodSecondswindow to become Ready before liveness/readiness probes start counting failures.Default tuning when enabled:
30 × 5s = 150sstartup window.Why
On 2026-05-26 the
earthly-internaldogfood cluster was rolled from Hub2.0.0→e845ff9d. The new Hub takes ~52s to become Ready (Postgres schema migration v175 → v182 + the newsqlapi_userrole creation). The existing chart probes are configured withinitialDelaySeconds=0, periodSeconds=5, failureThreshold=3— a 15s tolerance window — so kubelet killed the pod mid-migration in a crashloop.The workaround was an out-of-band
kubectl patch deploy/lunar-hubadding a startupProbe imperatively. That's incompatible with a futurehelm upgrade(would wipe the patch).Behaviour
hub.startupProbe.enabled: false(default)hub.startupProbe.enabled: truestartupProbe:block with/healthHTTP probeWhile the startupProbe is running, kubelet suppresses liveness/readiness probe failures. Once the startupProbe succeeds for the first time, control hands back to liveness/readiness for ongoing health checks (no double-coverage).
Test plan
helm templatewithhub.startupProbe.enabled=truerenders the full block (verified locally)helm templatewith default values renders zerostartupProbe:references (verified locally —grep -c startupProbereturns 0)earthly-internalcluster (replaces the kubectl-patched stopgap with chart-managed config) once this lands and the chart version bumpsNotes
hub.livenessProbe/hub.readinessProbeshape exactly for consistency.This PR was drafted by AI.