feat(ha): add drain-safe PDBs to the remaining critical controllers and apps

[devantler]

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Summary

Completes the #1880/#1882 drain-safe PDB sweep so node drains, Talos upgrades and autoscaler scale-down never take out a whole platform component at once — and never deadlock. Every change uses the house pattern maxUnavailable: 1, which the disruption controller evaluates against the live replica count, so it stays drainable even if a replica floor drops.

Chart-native values (chart supports the maxUnavailable shape)

Component	What gets a PDB
keda 2.20.0	operator, metrics-apiserver, admission-webhooks
external-secrets 2.5.0	controller, webhook, cert-controller (minAvailable: null removes the chart's default minAvailable shape that validate-pdb-drain-safe flags)
vpa 4.11.0	recommender + updater (mirrors the existing admissionController PDB)
kyverno 3.8.1	background/reports/cleanup controllers — the chart auto-enables their PDBs at replicas > 1 and defaults them to minAvailable: 1, so prod (3 replicas each) has been running the flagged shape; this pins maxUnavailable: 1 instead

Raw PDB manifests (no usable chart knob)

Component	Why raw
flagger	chart only offers minAvailable
keda-add-ons-http external scaler	chart ships a PDB only for the interceptor; the scaler is on the scale-from-zero decision path
snapshot-controller (hetzner)	piraeus chart has no PDB value; keeps Velero CSI snapshots from hanging mid-drain
umami	Flagger target — selector keys on app.kubernetes.io/instance because Flagger rewrites /name to umami-umami-primary on the primary (see canary.yaml); provision-tenants Job pods carry different labels and are not matched
actual-budget	KEDA scale-to-zero, inert at 0 replicas, never blocks a drain at 1

Explicitly unchanged

• OpenBao: at openbao_replicas: 3 the chart's default server.ha.disruptionBudget already renders maxUnavailable: 1 (verified against the 0.28.3 template math).
• Velero, flux-operator, external-dns, spire-server, coroot: intentional singletons / operator-managed, per validate-replica-floor exemptions.

Validation

• ksail workload validate: green (320 files)
• ksail --config ksail.prod.yaml workload validate: only failure is the pre-existing coroot schema gap in the upstream datreeio CRDs-catalog (fixed upstream by CRDs-catalog#896, unrelated)
• Every chart-value shape verified by rendering the exact chart version with helm template and inspecting the produced PDBs (all render maxUnavailable: 1; kyverno verified via its kyverno.pdb.spec helper which forbids setting both fields)

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[devantler]

🤖 Generated by the Daily AI Assistant

System-test status: the first run failed in ~3 min on a transient schema-fetch error during ksail workload validate (bases/apps ... validation failed: EOF — also hit #1995, which touches no manifests). On rerun, validate passed (✔ 320 files validated — including every PDB added here) and the job ran the full ~53 min, failing at reconcile with infrastructure Progressing / apps blocked — the known repo-wide OpenBao label-patch 422 wedge being probed in #1990 (same signature and duration as #1987/#1989, pre-existing on main). Nothing in this PR participates in the OpenBao seeding chain; it can go green once the 422 regression is fixed.

[devantler]

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Fixed the reported kyverno failure and merged origin/main into the branch. Root cause: the kyverno chart defaults each controller's podDisruptionBudget to minAvailable: 1, and Helm deep-merges user values onto chart defaults — so setting only maxUnavailable: 1 left both fields present, and the chart's kyverno.pdb.spec helper hard-fails the whole upgrade at render time wherever a controller runs >1 replica (prod runs 3). The fix adds an explicit minAvailable: null to all three controller PDB blocks, which deletes the chart-default key at value coalescing — the same mechanism the external-secrets values in this PR already use.

Verified by rendering kyverno 3.8.1 with all three controllers at 3 replicas: without the null the render reproduces the exact error; with it each controller gets a clean maxUnavailable: 1 PDB. keda and vpa are unaffected (their chart PDB defaults are {}, nothing to merge against). ksail workload validate green (323 files).

[devantler]

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System Test run 27361178852 (the first run after the kyverno minAvailable: null fix) failed on the known local-cluster infra flake, not on this PR's content: the single-control-plane Docker cluster's API server became unresponsive mid-reconcile — helm-controller/source-controller stuck in CreateContainerError on local-worker-2, lease-lock renewals timing out (the server was unable to return a response), client rate limiter ... context deadline exceeded across the board — which cascaded into infrastructure-controllers/infrastructure/apps reconcile failures. Same etcd-overload signature documented in #1779.

The kyverno values themselves are sound — independently verified by rendering chart 3.8.1 with the fixed values (minAvailable: null + maxUnavailable: 1 at 3/2/2 replicas renders the three PDBs correctly), and prod's kyverno helm upgrade succeeded once main-based artifacts re-deployed at ~16:45 (kyverno.v8).

FYI: the wider incident this PR's merge-queue attempt caused is written up in #2026 (merge-group deploys leave prod on unmerged code when the group fails).

[devantler]

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The 16:18 run on 399f924c is an infra flake, not a regression: cluster create needed a retry on a slow etcd (service etcd not in expected state Running), and the reconcile then cascaded with apiserver rate-limiter timeouts (failed to list pods in flux-system: client rate limiter Wait returned an error: context deadline exceeded) taking down 3/5 Kustomizations including infrastructure-controllers — the known single-CP Docker etcd-overload flake. No Cannot set both anywhere in the log and no kyverno HelmRelease failure, and the 15:35 run on 6be628a1 (same PDB content, pre-null-fix merge) passed the full system test. Re-running the failed job.

[devantler]

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The 17:36 run on 94a3980f is the same infra flake as the 16:18 one, with clearer evidence this time: from early in the run the Flux controllers could not even renew their leader-election leases (Error retrieving lease lock ... Client.Timeout exceeded / the server was unable to return a response in the time allotted), source-controller and helm-controller sat 0/1 Ready, CoreDNS answered 503, and every HelmChart reported 'latest generation has not been reconciled' — cluster-wide API-server starvation on the single-CP Docker cluster, the documented etcd-overload flake. No manifest in this PR is implicated (identical content passed the full system test at 15:35). Re-running.

[devantler]

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Third occurrence of the runner-starvation flake on this branch (this time visible at the lowest level: kube-scheduler itself timing out lease renewal against KubePrism at 127.0.0.1:7445 — below anything Flux deploys). Cross-checking the rest of the fleet this afternoon: six merge-queue and PR runs passed in the same window (including the PDB-policy PR #2025 and the velero-group fix #2031), one unrelated PR flaked the same way. Identical content passed the full system test at 15:35. PDB objects are inert at admission and cannot load an apiserver; this branch is just rolling badly on the runner lottery. Re-running (attempt 4).