jakman85andClaude Opus 4.8
28a34c4477
Admission controller was crashlooping (9 restarts/4h, exit 255, NOT OOM: live usage ~65Mi/384Mi limit, 7m cpu). Root cause: chart-default 100m CPU request starved the process under node contention, so client-go calls hit context-deadline-exceeded, leader-election lease renewal timed out, leadership was lost and the webhook server closed. Raise the CPU request to 250m (no CPU limit, to avoid CFS throttling) with modest memory headroom (256Mi/512Mi), and raise dev admission replicas 1->2 so a single fail-closed pod restart no longer 502s cluster-wide admission-gated writes. Co-Authored-By: Claude Opus 4.8 <[email protected]>
In-cluster admission enforcement (scaffolding — Phase 2 / T-2.7)
Installs Kyverno and runs the same L0 policies as an in-cluster admission
controller, so a non-conforming resource that somehow bypassed CI still cannot be
admitted (defense in depth — docs/07, ADR-0011). Not applied in Phase 0 (no
cluster exists yet); this is scaffolding wired up in task T-2.7.
Enforcement COMPLEMENTS, never REPLACES, behavior tests
A policy admitting a manifest is not proof the runtime behaves (
docs/14principle 1, R-TEST-01). Kyverno confirms a resource is shaped correctly; it does not prove default-deny actually blocks a packet, that the VPN kill-switch fails closed, or that a PVC survives a rebuild. Those are proven only by the L2/L3 Chainsaw behavior and fault-injection tests (conformance/, ADR-0011), which remain mandatory. Admission is a gate, not a guarantee of behavior.
Authored once, shared
kustomization.yaml references the policy files in ../policies/ verbatim — the
identical objects the CI kyverno test gate validates — plus the Kyverno install.
No policy is forked between CI and admission, with one deliberate exception:
The one deliberate CI vs admission divergence — Secrets
../policies/disallow-plaintext-secrets.yaml (CI) requires a top-level sops block
on the Secret manifest. Flux decrypts SOPS before admission, so that block is
gone by the time the API server sees the Secret — the CI policy cannot run in-cluster.
The admission equivalent is secret-provenance.yaml, which enforces provenance
(Secret came from Flux / is an exempt controller Secret) instead of ciphertext. This
is escalated in the T-0.5 report because docs/07's literal wording ("reject a
plaintext Secret at admission") is not achievable post-decrypt.
Operational note (from ADR-0011)
Admission enforcement adds a failure mode: a bad policy can block legitimate
reconciliation. Mitigations: policies ship with their own kyverno test suite (this
directory's ../tests), roll out via GitOps, and the webhook failurePolicy: Fail
is chosen so the system fails closed (coordination-protocol.md #8) — validate for
bootstrap deadlocks in dev/test before prod.