feat(ha): the CNI dials the control-plane VIP — kube-vip becomes a CNI prerequisite

OPERATOR DECISION 2026-09-06: "use the VIP as intended — a virtual address to reach
the cluster and provide fault tolerant HA. Without a change it will not work in HA."

THE DEFECT. Cilium's kube-proxy replacement dialled a SINGLE NODE. Re-confirmed live
before changing anything: all three prod cilium-agent pods carried
KUBERNETES_SERVICE_HOST=192.168.2.10 — k3s-prod-1's own address — while the kube-vip
VIP 192.168.2.9 was Running on all three nodes with a held lease. Lose prod-1 and the
CNI's control-plane path is dead on an "HA" cluster. clusters/prod's own comment said
the value must be the VIP and NOT .10, then called it "Not yet decided" — I treated
that stale comment as an open question when the evidence already settled it.

SPLIT, NOT REPOINT, because k3s_api_host had two consumers with opposite needs:
  k3s_api_host            unchanged — the FOUNDER's IP: the cold-bootstrap join
                          target and a tls-san. infra/tofu/outputs.tf GENERATES this
                          name, so renaming would ripple into tofu and the runbooks.
  k3s_apiserver_endpoint  NEW = {{ kube_vip_address }} — the HA address; what Cilium
                          consumes. Derived, not restated, so an environment overrides
                          ONE line and the VIP, the SAN and the CNI endpoint move
                          together. Prod needed no new override.

THE SECOND HAZARD, WHICH MY BRIEF DID NOT NAME and the agent found: pointing Cilium at
the VIP breaks a COLD bootstrap for the same reason the join would — site.yml ran
node-baseline -> k3s -> cilium, so Cilium would install against an address nothing
announced yet. That is the 2026-09-01 deadlock shape. Fixed by SEQUENCE, not value:
site.yml now imports kube-vip.yml BETWEEN k3s and cilium. It cannot go earlier
(kube-vip is a k3s auto-deploy manifest, so it needs a cluster) and it works there
because the DaemonSet is hostNetwork with KUBERNETES_SERVICE_HOST=127.0.0.1 — needing
neither CNI nor kube-proxy. roles/kube_vip gained a read-only `wait_for` on the VIP so
a cold run stops THERE with a named cause instead of surfacing as unreachable agents.

Also fixed a pre-existing bug that only mattered once this play joined site.yml: the
role's read-only interface probe ran without `check_mode: false`, so under --check it
was skipped and the assert fired with a misleading "set kube_vip_interface explicitly".

VERIFIED BY ME, not just reported:
  renders    dev K3S_API_HOST=192.168.1.49   prod=192.168.2.9  (each environment's VIP)
  cilium     template consumes k3s_apiserver_endpoint, not k3s_api_host
  cold join  still `--server https://{{ k3s_api_host }}:6443` — the founder
  order      site.yml: node-baseline -> k3s -> kube-vip -> cilium -> verify -> flux
  gate       full CI gate PASS
Agent-side, additionally: in-memory render of cilium-values.yaml.j2 per host showing
k8sServiceHost=the VIP with the join still on the founder; k3s_tls_sans renders
['.10','.9','127.0.0.1','.11','.12'] so NO cert reissue and NO k3s restart is involved
— .9 already answers under full CA verification; and --check --diff of kube-vip.yml
against prod reported 6 ok / 0 changed, i.e. the role edits change nothing about the
kube-vip prod already runs.

ha-control-plane-as-code 92 -> 112 assertions, turning two escalations into machine
checks: the Cilium template must use the endpoint var; the endpoint must derive from
kube_vip_address and k3s_api_host must not; per environment K3S_API_HOST must equal
that environment's VIP and be none of its node IPs (the [parity] contract, now
machine-checked rather than a comment); site.yml must order k3s -> kube-vip -> cilium.
Every new assertion mutation-tested and bites. One honest negative recorded: reverting
only the BASE default is not caught, because both overlays patch the key — the check
reads effective per-environment values, so the base default is unguarded.

APPLY ORDER, and this is the operator's step — nothing was applied:
  PROD FIRST, and it is the low-risk direction (prod is the broken one). Push and let
  Flux reconcile platform/cilium: the value change rolls the cilium-agent DaemonSet
  ONE NODE AT A TIME (maxUnavailable: 1 — the knob that bounded the 2026-09-01
  incident), it will not proceed past an unready pod, existing datapath survives an
  agent restart, and .9 is already live before the change lands.
  DEV SEPARATELY, operator present. Same mechanics but live dev agents dial
  192.168.1.50, and dev is mid-DNS-migration on dev-live. Do not fold it into that.
  ANSIBLE: nothing to run for either live cluster; the Ansible half matters only for a
  cold build. Remove the now-redundant standalone kube-vip.yml step from any runbook.

NEW NAMED GAP, unwritten: the L2 test cannot assert the running agents' live
KUBERNETES_SERVICE_HOST, which is the drift the L0 check cannot see. Recorded in that
test's gap list.

Refs R-PLAT-01, R-NET-01, R-ENV-02.

Co-Authored-By: Claude Opus 5 <[email protected]>

platform/cilium/helmrelease.yaml

@@ -10,7 +10,8 @@
 #
 # SOURCE OF TRUTH (do not diverge without updating both):
 #   infra/ansible/roles/cilium/templates/cilium-values.yaml.j2
-#   infra/ansible/roles/cilium/defaults/main.yml   (cilium_version, k3s_api_host/port)
+#   infra/ansible/roles/cilium/defaults/main.yml   (cilium_version)
+#   infra/ansible/inventory/group_vars/all.yml     (k3s_apiserver_endpoint, k3s_api_port)
 #
 # Every value tagged [parity] below is asserted identical to the Ansible render. If you change one
 # here, change it in the Ansible role in the same PR. (docs/02 Cilium-ownership contract.)
@@ -45,11 +46,35 @@ spec:
     # [parity] MUST equal Ansible: kubeProxyReplacement: true
     kubeProxyReplacement: true
     # [parity] MUST equal Ansible: k8sServiceHost/k8sServicePort = the k3s API endpoint
-    # (k3s_api_host/k3s_api_port). This is the primary control-plane node IP.
+    # (**k3s_apiserver_endpoint** / k3s_api_port, infra/ansible/inventory/group_vars/all.yml).
     # Setting these wrong breaks Cilium's connection to the API server on adopt.
-    # ${K3S_API_HOST} (cluster-vars, R-ENV-02): dev 192.168.1.50 | prod set in clusters/prod.
-    # The `platform` Flux Kustomization substitutes it; the Ansible side is already parameterized
-    # from inventory (k3s_api_host), so the parity contract holds per-environment, not per-literal.
+    #
+    # THIS IS THE CONTROL-PLANE VIP (kube-vip), NOT A NODE ADDRESS — operator decision 2026-09-06.
+    # ${K3S_API_HOST} (cluster-vars, R-ENV-02): dev 192.168.1.49 | prod 192.168.2.9, each equal to
+    # that environment's kube_vip_address. The knob's NAME still says "host"; read it as "the API
+    # host Cilium dials", and see clusters/base/cluster-vars.yaml for why it was not renamed.
+    #
+    # WHY, in one line: this value used to be the PRIMARY NODE's IP, so on a 3-server HA cluster the
+    # CNI's control-plane path depended on one machine. Verified on live prod 2026-09-06 — every
+    # cilium-agent carried KUBERNETES_SERVICE_HOST=192.168.2.10 (k3s-prod-1) while kube-vip held .9.
+    # Losing that node does not break the datapath (Cilium keeps serving from cache); it silently
+    # stops every service and policy update from ever landing, which is worse to detect.
+    #
+    # [parity] IS NOW AGAINST k3s_apiserver_endpoint AND NOT k3s_api_host. Those were one Ansible
+    # variable until 2026-09-06 and the conflation is the defect. k3s_api_host still exists and
+    # still holds the FOUNDER's own address, because roles/k3s_server's secondary
+    # `--server https://<host>:6443` join must target a host that is already up — on a COLD build
+    # no VIP exists yet. So: founder for the join, VIP for the CNI. If you change this line, change
+    # cilium-values.yaml.j2 in the same PR, and point it at the SAME variable.
+    #
+    # The `platform` Flux Kustomization substitutes it; the Ansible side is parameterized from
+    # inventory (k3s_apiserver_endpoint derives from kube_vip_address), so the parity contract holds
+    # per-environment, not per-literal.
+    #
+    # NEEDS NO CERT WORK: k3s_tls_sans has always carried kube_vip_address alongside every node IP,
+    # so both addresses are already SANs on the serving cert (verified live 2026-09-06 — prod
+    # answers through https://192.168.2.9:6443 under full CA verification, no insecure skip). This
+    # switch reissues nothing and restarts no apiserver.
     k8sServiceHost: "${K3S_API_HOST}"
     k8sServicePort: 6443
     # --- Gateway API (ingress; replaces Traefik) — docs/09, ADR-0002 ---

platform/cilium/values.yaml

@@ -6,16 +6,20 @@
 #
 # SOURCE OF TRUTH (all [parity] fields MUST equal these):
 #   infra/ansible/roles/cilium/templates/cilium-values.yaml.j2
-#   infra/ansible/roles/cilium/defaults/main.yml   (cilium_version: 1.20.1, k3s_api_host/port)
+#   infra/ansible/roles/cilium/defaults/main.yml   (cilium_version: 1.20.1)
+#   infra/ansible/inventory/group_vars/all.yml     (k3s_apiserver_endpoint = the kube-vip VIP,
+#                                                   k3s_api_port) — NOT k3s_api_host, which is the
+#                                                   founder's own address and bootstrap-only
 #
 # chart version (helmrelease.yaml chart.spec.version): 1.20.1   # [parity] = cilium_version
 
 # [parity] k3s kube-proxy disabled → Cilium replaces it (ADR-0001/0002)
 kubeProxyReplacement: true
-# [parity] = the k3s API endpoint (primary control-plane node IP) + port.
+# [parity] = the k3s API endpoint + port. THE CONTROL-PLANE VIP (kube-vip), not the primary node —
+# changed 2026-09-06; the Ansible half is k3s_apiserver_endpoint, NOT k3s_api_host.
 # Mirrors the HelmRelease's ${K3S_API_HOST} cluster-vars token (R-ENV-02). This file is NOT a
 # kustomize resource, so nothing substitutes it — the token is shown with its dev value beside it.
-k8sServiceHost: "${K3S_API_HOST}"   # dev: 192.168.1.50
+k8sServiceHost: "${K3S_API_HOST}"   # the CONTROL-PLANE VIP — dev: 192.168.1.49 | prod: 192.168.2.9
 k8sServicePort: 6443
 # [parity] ingress via Gateway API, no Traefik (docs/09)
 gatewayAPI: