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revert(vpn-ingress): withdraw the L2 lease-collision fix — a node CAN reach a VIP it announces
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PR #69 claimed a node cannot reach a LoadBalancer VIP whose Cilium L2 announcement
lease it holds, and excluded the VPN ingress node from announcing on that basis.
The claim makes a sharp prediction; today's power-cycle put ALL EIGHT
cilium-l2announce-* leases on k3s-prod-1, and the prediction failed.

Measured 2026-10-17 from the wireguard pod's host netns on each node: the holder
reaches 192.168.2.20/.22/.23/.24 normally (curl 200 in 18ms on .20) while its
ip neigh for every one of them sits at FAILED. The asserted cause is present
without the asserted effect, which falsifies it. .21 (unifi) fails from all three
nodes and is a separate pre-existing fault.

It is inert because no path resolves a VIP by ARP: cilium-dbg reports
KubeProxyReplacement on [eno1, wg0] and programs 192.168.2.20:443 =>
127.0.0.1:13606, so VIPs are DNAT'd in BPF before any neighbour lookup, on the
forwarded path as well as the host one.

Both probes behind the original diagnosis were bad. `ip neigh` FAILED is
permanent and harmless, and a ping artefact. `curl --interface wg0` — the control
used to rule out a host-netns artefact — fails on all three nodes, including ones
whose ARP resolves, so it discriminates nothing. The deeper error: a MASQUERADEd
client is FORWARDED while every pod-runnable probe is socket-originated. Sharing
a netns is not sharing a hook.

Reverted the policy nodeSelector, the Ansible node label, both alerts, their
promtool tests and the kube-state-metrics allowlist entry. Kept documentation
only: the measurements, which probes lie, and the fact that the forwarded path
remains unmeasured without a connected client.

Also recorded, for the reported "LAN and cluster work, internet does not":
new-peer.sh has emitted a FULL tunnel (0.0.0.0/0) by default since f92707f, so
there is no full-tunnel option to add and no code change is made. The server side
is capable — ip_forward=1, the 10.90.0.0/24 MASQUERADE present with an empty
CILIUM_POST_nat ahead of it, FORWARD accepts, default route intact, nodes reach
1.1.1.1. A full tunnel egresses the HOUSE WAN, not PIA: the egress policy selects
pods by egress-class=vpn, this pod is labelled internet, and tun0 exists on
k3s-prod-3 only. Root cause NOT found; no client has connected since the
power-cycle (0 forwarded packets, no handshake), so it is not reproducible here.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
This commit is contained in:
jakman85andClaude Opus 5 committed 2026-10-17 23:58:40 -05:00
1 parent 4656b07178
commit e82dab5df5
13 files changed
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platform/monitoring/alerts.yaml
-91
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@@ -1147,97 +1147,6 @@ spec:
metricLabelsAllowlist.
runbook_url: "https://${BASE_DOMAIN}/runbooks/vpn-egress-stale"
# -----------------------------------------------------------------------------------------
# REMOTE-ACCESS VPN (platform/vpn-ingress) -- NOT the egress tunnel above. Different
# direction, different workload: this is inbound WireGuard for remote devices.
# -----------------------------------------------------------------------------------------
- alert: VpnIngressNodeAnnouncesL2VIP
# THE FAILURE THIS CATCHES. MEASURED on prod 2026-10-08: a node CANNOT reach a
# LoadBalancer VIP whose Cilium L2 announcement lease it holds itself -- the announcer
# does not answer its own ARP request, so the neighbour entry settles at `FAILED` and
# packets die before leaving the node (`ip neigh show 192.168.2.20` -> FAILED on the
# lease holder, resolved on both others). platform/vpn-ingress runs WireGuard on
# `hostNetwork` and MASQUERADEs remote clients to the node's own address, so if the node
# the router forwards udp/51820 to is also a lease holder, VPN clients cannot reach the
# VIPs it announces. On 2026-10-08 that was the `shared` Gateway: all 16 app hostnames
# dead over the VPN, while PiHole DNS kept answering (its VIP has two Services and the
# other lease sat on prod-2) -- so the tunnel handshook, names resolved, and every app
# hung. Nothing reported it for ~2 days.
#
# platform-config/cilium/l2-announcement-policy.yaml now excludes the node labelled
# `homelab.keithjackson.dev/vpn-ingress=true` from announcing, so this should be
# permanently unsatisfiable. The alert exists because the exclusion has ways to stop
# working that no static check on that file's TEXT can see: the label being removed or
# moved to the wrong node, a Cilium upgrade changing `NotIn` semantics or the
# nodeSelector field, and the selector silently failing to match. This watches the
# OUTCOME -- who actually holds the lease -- so all of them surface the same way.
#
# WHY THE LABEL JOIN RATHER THAN A NODE NAME. The node's identity is NOT written into
# this expr, because the harness (tests/extract_rules.py) refuses any alert whose expr
# contains a dollar-brace placeholder -- spelled in words because a literal one here is
# unparseable to envsubst and would fail this whole Kustomization. Rightly so: the rule it
# unit-tests would not be the
# rule deployed. Joining `kube_lease_owner` against `kube_node_labels` keeps ONE source
# of truth (the label itself, which is also what the policy selects on), so this alert
# cannot drift out of agreement with the exclusion it guards. `label_replace` is needed
# because kube_lease_owner names the holder `lease_holder` while kube_node_labels names
# it `node`; the join is then on a shared `node` label. The label is in
# kube-state-metrics' metricLabelsAllowlist (kube-prometheus-stack.yaml) -- without that
# line this rule is inert, which `VpnIngressNodeLabelMissing` below exists to catch.
#
# `for: 15m` because leases legitimately move during a node reboot or a Cilium roll and
# Cilium re-elects within seconds; a real collision persists, since the lease holder
# keeps renewing and it never self-heals.
expr: |
max by (lease) (
label_replace(
kube_lease_owner{namespace="kube-system", lease=~"cilium-l2announce-.*"},
"node", "$1", "lease_holder", "(.+)"
)
* on (node) group_left ()
kube_node_labels{label_homelab_keithjackson_dev_vpn_ingress="true"}
) == 1
for: 15m
labels:
severity: critical
annotations:
summary: "VPN ingress node is announcing a LoadBalancer VIP ({{ $labels.lease }})"
description: >-
The node labelled homelab.keithjackson.dev/vpn-ingress=true terminates remote-access
WireGuard, and it now holds the Cilium L2 announcement lease `{{ $labels.lease }}`. A
node cannot reach a VIP it announces itself, so every remote VPN client has just lost
all access to that VIP's Service -- silently, with DNS still resolving. Check that
platform-config/cilium/l2-announcement-policy.yaml still excludes that label and that
the label is still on the node the router forwards udp/51820 to.
runbook_url: "https://${BASE_DOMAIN}/runbooks/vpn-ingress-l2-collision"
- alert: VpnIngressNodeLabelMissing
# THE WATCHDOG for the rule above, and the reason it is not optional. The exclusion in
# l2-announcement-policy.yaml is a `NotIn` on this label, and `NotIn` with an ABSENT key
# MATCHES -- so if the label is on NO node, the policy excludes nothing, every node is an
# announcement candidate again, and the 2026-10-08 failure is fully re-armed. The alert
# above would not fire either: its join would match nothing and return no series. Present,
# evaluating, and incapable of firing -- the exact "inert critical alert" shape that
# VPNEgressUplinkLabelMissing exists for on the egress side, and that this repo has been
# burned by before.
#
# The label is applied by infra/ansible/roles/node_baseline
# (node_baseline_vpn_ingress_node); the most likely cause of it going absent is a node
# rebuild where that role has not been re-run.
expr: absent(kube_node_labels{label_homelab_keithjackson_dev_vpn_ingress="true"})
for: 30m
labels:
severity: warning
annotations:
summary: "No node carries the vpn-ingress label -- VPN VIP protection is OFF"
description: >-
No node publishes homelab.keithjackson.dev/vpn-ingress=true, so
l2-announcement-policy.yaml's `NotIn` exclusion matches every node and excludes none:
any node may now announce a LoadBalancer VIP, including the one terminating
remote-access WireGuard. `VpnIngressNodeAnnouncesL2VIP` is INERT while this fires, so
the warning matters more than its severity suggests. Re-run the node_baseline role on
the forwarded node, and confirm the label is in kube-state-metrics'
metricLabelsAllowlist.
runbook_url: "https://${BASE_DOMAIN}/runbooks/vpn-ingress-l2-collision"
# -----------------------------------------------------------------------------------------
# (ADR-0015) The former `EgressGatewayUnhealthy` pod-readiness alert was REMOVED with the gluetun
# retirement: there is no in-cluster egress-gateway pod anymore (the tunnel is a host systemd
# service, steering is Cilium eBPF). Tunnel + gateway-node health is covered by `VPNTunnelDown`
platform/monitoring/kube-prometheus-stack.yaml
+1 -13
View File
@@ -281,20 +281,8 @@ spec:
# without anyone having to remember to re-enable it later. Scoped to one label on one resource:
# 3 extra series, no cardinality concern. Label name is sanitized by KSM to
# `label_homelab_keithjackson_dev_egress_gateway` (`label_` + non-alphanumerics -> `_`).
# `vpn-ingress` (added 2026-10-17) marks the node the SOHO router forwards WAN udp/51820 to.
# platform-config/cilium/l2-announcement-policy.yaml excludes that node from announcing any
# LoadBalancer VIP, because a node cannot reach a VIP whose L2 announcement lease it holds
# itself and vpn-ingress MASQUERADEs remote clients to the node's own address (measured
# 2026-10-08: all 16 Gateway hostnames dead over the VPN while DNS still resolved). It is
# allowlisted HERE because that is the only way the invariant can be WATCHED:
# `VpnIngressNodeAnnouncesL2VIP` joins `kube_lease_owner` against this label, and the alert
# unit-test harness refuses a dollar-brace placeholder in an alert expr (written out in words:
# a literal one here is unparseable to envsubst and fails the whole Kustomization), so a knob
# could not have been used. Without this line BOTH that alert and its
# `VpnIngressNodeLabelMissing` watchdog are structurally inert. Same reasoning, and the same
# 3-extra-series cost, as the two egress labels below.
metricLabelsAllowlist:
- "nodes=[homelab.keithjackson.dev/egress-gateway,homelab.keithjackson.dev/egress-uplink,homelab.keithjackson.dev/vpn-ingress]"
- "nodes=[homelab.keithjackson.dev/egress-gateway,homelab.keithjackson.dev/egress-uplink]"
# --- VELERO SCHEDULE OBJECTS AS METRICS (added 2026-09-13) ---------------------------------
# Velero exports NOTHING that enumerates Schedule objects and nothing that exposes
# `spec.paused`. Verified on prod against velero v1.18.1: all 35 velero_* metric names that
platform/monitoring/tests/vpn-ingress-l2.test.yaml
-203
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@@ -1,203 +0,0 @@
# promtool rule-unit tests for VpnIngressNodeAnnouncesL2VIP + VpnIngressNodeLabelMissing
# (platform/monitoring/alerts.yaml)
#
# Run with: platform/monitoring/tests/run.sh
# (the merge gate runs the same harness via
# conformance/tests/l0-static/alert-rules-unit-tested)
#
# WHAT THESE RULES CLAIM, AND WHY IT NEEDS PINNING IN BOTH DIRECTIONS
# MEASURED on prod 2026-10-08: a node cannot reach a LoadBalancer VIP whose Cilium L2 announcement
# lease it holds ITSELF -- the announcer does not answer its own ARP request, so on the lease holder
# the neighbour entry settles at `FAILED` and packets to that VIP die before leaving the node.
# platform/vpn-ingress runs WireGuard on `hostNetwork` and MASQUERADEs remote clients to the node's
# own address, so a VPN client takes that node's LAN path and inherits the failure. With the
# router's udp/51820 forward on k3s-prod-1, which held the `shared` Gateway lease, all 16 Gateway
# hostnames were dead over the VPN -- while PiHole DNS kept answering, because its VIP has two
# Services and k3s-prod-2 held the other lease. The tunnel handshook, names resolved, every app
# hung, and nothing reported it for ~2 days.
#
# platform-config/cilium/l2-announcement-policy.yaml now excludes the node labelled
# `homelab.keithjackson.dev/vpn-ingress=true` from announcing, so VpnIngressNodeAnnouncesL2VIP
# should be permanently unsatisfiable. THAT IS EXACTLY WHY IT NEEDS A TEST: an alert expected never
# to fire is indistinguishable, in production, from an alert that CANNOT fire. Nothing would ever
# reveal a mistyped label, a broken `label_replace`, or a join on the wrong label. Test 1 proves it
# fires on the real failure; test 2 proves it is quiet in the fixed state, so it is not a rule that
# fires on anything; test 3 pins the `for: 15m` against routine lease churn.
#
# THE JOIN IS THE FRAGILE PART AND IS TESTED DELIBERATELY. `kube_lease_owner` names the holder in
# `lease_holder`; `kube_node_labels` names it `node`. The rule bridges them with `label_replace`
# and joins `on (node) group_left ()`. Fixtures therefore carry BOTH series shapes with real label
# sets, because a join that silently matches nothing returns no series -- which looks exactly like
# "healthy" and is the failure mode this whole group exists to prevent.
#
# Fixture values are prod's real shape (measured 2026-10-08): leases
# `cilium-l2announce-gateway-cilium-gateway-shared` (k3s-prod-1) and
# `cilium-l2announce-pihole-pihole-dns-tcp` (k3s-prod-2), in namespace kube-system, with
# k3s-prod-1 the vpn-ingress node.
rule_files:
- generated.rules.yaml
evaluation_interval: 1m
tests:
# =============================================================================================
# 1. THE BUG, EXACTLY AS IT HAPPENED -- the vpn-ingress node holds the Gateway lease: FIRES.
# =============================================================================================
- interval: 1m
name: vpn-ingress node holds the shared Gateway L2 lease - VpnIngressNodeAnnouncesL2VIP fires
input_series:
# The collision. A lease holder keeps renewing, so this series does not lapse on its own --
# which is why the condition never self-heals and why a 15m `for:` is safe.
- series: 'kube_lease_owner{job="kube-state-metrics",namespace="kube-system",lease="cilium-l2announce-gateway-cilium-gateway-shared",lease_holder="k3s-prod-1"}'
values: '1+0x40'
# A second lease held by a DIFFERENT node, present throughout. This is the discriminator that
# stops the rule from being "any l2announce lease exists anywhere": if the join were dropped,
# this series alone would fire the alert, and test 2 would fail.
- series: 'kube_lease_owner{job="kube-state-metrics",namespace="kube-system",lease="cilium-l2announce-pihole-pihole-dns-tcp",lease_holder="k3s-prod-2"}'
values: '1+0x40'
# k3s-prod-1 is the vpn-ingress node. Only this node carries the label.
- series: 'kube_node_labels{job="kube-state-metrics",node="k3s-prod-1",label_homelab_keithjackson_dev_vpn_ingress="true"}'
values: '1+0x40'
# The other two nodes publish kube_node_labels WITHOUT the vpn-ingress label. Present so the
# join is exercised against non-matching nodes rather than against nothing at all.
- series: 'kube_node_labels{job="kube-state-metrics",node="k3s-prod-2"}'
values: '1+0x40'
- series: 'kube_node_labels{job="kube-state-metrics",node="k3s-prod-3"}'
values: '1+0x40'
alert_rule_test:
# Held 15m, so nothing before then.
- eval_time: 14m
alertname: VpnIngressNodeAnnouncesL2VIP
exp_alerts: []
- eval_time: 20m
alertname: VpnIngressNodeAnnouncesL2VIP
exp_alerts:
# EXACTLY ONE alert: the pihole lease on prod-2 must NOT produce a second one.
- exp_labels:
severity: critical
lease: cilium-l2announce-gateway-cilium-gateway-shared
exp_annotations:
summary: "VPN ingress node is announcing a LoadBalancer VIP (cilium-l2announce-gateway-cilium-gateway-shared)"
description: >-
The node labelled homelab.keithjackson.dev/vpn-ingress=true terminates remote-access
WireGuard, and it now holds the Cilium L2 announcement lease `cilium-l2announce-gateway-cilium-gateway-shared`. A
node cannot reach a VIP it announces itself, so every remote VPN client has just lost
all access to that VIP's Service -- silently, with DNS still resolving. Check that
platform-config/cilium/l2-announcement-policy.yaml still excludes that label and that
the label is still on the node the router forwards udp/51820 to.
runbook_url: "https://${BASE_DOMAIN}/runbooks/vpn-ingress-l2-collision"
# The label IS present, so the watchdog must stay quiet here.
- eval_time: 40m
alertname: VpnIngressNodeLabelMissing
exp_alerts: []
# =============================================================================================
# 2. THE FIXED STATE -- every lease is held by a node that is NOT the vpn-ingress node: QUIET.
# This is what l2-announcement-policy.yaml's exclusion produces, and the assertion that keeps
# test 1 meaningful rather than an alert that fires on anything.
# =============================================================================================
- interval: 1m
name: all l2 leases held by other nodes - VpnIngressNodeAnnouncesL2VIP stays quiet
input_series:
- series: 'kube_lease_owner{job="kube-state-metrics",namespace="kube-system",lease="cilium-l2announce-gateway-cilium-gateway-shared",lease_holder="k3s-prod-2"}'
values: '1+0x40'
- series: 'kube_lease_owner{job="kube-state-metrics",namespace="kube-system",lease="cilium-l2announce-plex-plex-l4-tcp",lease_holder="k3s-prod-3"}'
values: '1+0x40'
# A lease the vpn-ingress node DOES legitimately hold, in a different family -- proves the
# `cilium-l2announce-.*` matcher is doing work. Every node holds operator/controller leases;
# only the ANNOUNCEMENT ones matter here, and a matcher broad enough to catch this would page
# on a healthy cluster forever.
- series: 'kube_lease_owner{job="kube-state-metrics",namespace="kube-system",lease="cilium-operator-resource-lock",lease_holder="k3s-prod-1"}'
values: '1+0x40'
- series: 'kube_node_labels{job="kube-state-metrics",node="k3s-prod-1",label_homelab_keithjackson_dev_vpn_ingress="true"}'
values: '1+0x40'
- series: 'kube_node_labels{job="kube-state-metrics",node="k3s-prod-2"}'
values: '1+0x40'
- series: 'kube_node_labels{job="kube-state-metrics",node="k3s-prod-3"}'
values: '1+0x40'
alert_rule_test:
- eval_time: 40m
alertname: VpnIngressNodeAnnouncesL2VIP
exp_alerts: []
- eval_time: 40m
alertname: VpnIngressNodeLabelMissing
exp_alerts: []
# =============================================================================================
# 3. A LEGITIMATE, TRANSIENT LEASE MOVE -- the vpn-ingress node holds it for 11m during a node
# reboot or a Cilium roll, then Cilium re-elects away: QUIET. This pins the `for: 15m` as
# deliberate. Without it, every rolling restart of the cilium DaemonSet would page, and a paging
# alert that cries wolf on routine maintenance gets muted -- which is how the real collision
# would go unseen again.
# =============================================================================================
- interval: 1m
name: transient lease move shorter than for 15m - VpnIngressNodeAnnouncesL2VIP stays quiet
input_series:
# Held by the vpn-ingress node for 11 samples, then the series goes absent (the lease moved,
# so kube-state-metrics retires this label set and starts a new one).
- series: 'kube_lease_owner{job="kube-state-metrics",namespace="kube-system",lease="cilium-l2announce-gateway-cilium-gateway-shared",lease_holder="k3s-prod-1"}'
values: '1+0x10 _x30'
# Re-elected onto prod-3 from t=11m. A label VALUE change retires one series and starts
# another, which is why this is a second series and not a changing value.
- series: 'kube_lease_owner{job="kube-state-metrics",namespace="kube-system",lease="cilium-l2announce-gateway-cilium-gateway-shared",lease_holder="k3s-prod-3"}'
values: '_x11 1+0x29'
- series: 'kube_node_labels{job="kube-state-metrics",node="k3s-prod-1",label_homelab_keithjackson_dev_vpn_ingress="true"}'
values: '1+0x40'
alert_rule_test:
# Inside the transient window: pending at most, never firing.
- eval_time: 10m
alertname: VpnIngressNodeAnnouncesL2VIP
exp_alerts: []
# Well past it, with the lease settled on another node.
- eval_time: 30m
alertname: VpnIngressNodeAnnouncesL2VIP
exp_alerts: []
# =============================================================================================
# 4. THE WATCHDOG -- no node carries the label at all. The policy's `NotIn` then excludes
# NOTHING (a missing key matches), so the 2026-10-08 failure is fully re-armed, AND
# VpnIngressNodeAnnouncesL2VIP is structurally INERT: its join matches nothing and returns no
# series, which is indistinguishable from healthy. Both halves are asserted here, because an
# inert critical alert is the exact shape this repo has been burned by before.
# =============================================================================================
- interval: 1m
name: vpn-ingress label absent everywhere - watchdog fires and the critical alert is inert
input_series:
# A lease held by the node that IS (in reality) the forwarded one -- but with no label
# anywhere, nothing can tell. This is the dangerous state.
- series: 'kube_lease_owner{job="kube-state-metrics",namespace="kube-system",lease="cilium-l2announce-gateway-cilium-gateway-shared",lease_holder="k3s-prod-1"}'
values: '1+0x60'
- series: 'kube_node_labels{job="kube-state-metrics",node="k3s-prod-1"}'
values: '1+0x60'
- series: 'kube_node_labels{job="kube-state-metrics",node="k3s-prod-2"}'
values: '1+0x60'
- series: 'kube_node_labels{job="kube-state-metrics",node="k3s-prod-3"}'
values: '1+0x60'
alert_rule_test:
# The critical alert CANNOT fire -- this is the inertness being pinned, not an aside.
- eval_time: 45m
alertname: VpnIngressNodeAnnouncesL2VIP
exp_alerts: []
# ... which is precisely why the watchdog must.
- eval_time: 45m
alertname: VpnIngressNodeLabelMissing
exp_alerts:
- exp_labels:
severity: warning
# absent() propagates the matcher's own labels onto the series it returns, so the
# alert inherits this one. Asserted rather than worked around: it is harmless, and
# pinning it means a future change to the matcher cannot alter the alert's identity
# (and therefore its Alertmanager grouping) unnoticed.
label_homelab_keithjackson_dev_vpn_ingress: "true"
exp_annotations:
summary: "No node carries the vpn-ingress label -- VPN VIP protection is OFF"
description: >-
No node publishes homelab.keithjackson.dev/vpn-ingress=true, so
l2-announcement-policy.yaml's `NotIn` exclusion matches every node and excludes none:
any node may now announce a LoadBalancer VIP, including the one terminating
remote-access WireGuard. `VpnIngressNodeAnnouncesL2VIP` is INERT while this fires, so
the warning matters more than its severity suggests. Re-run the node_baseline role on
the forwarded node, and confirm the label is in kube-state-metrics'
metricLabelsAllowlist.
runbook_url: "https://${BASE_DOMAIN}/runbooks/vpn-ingress-l2-collision"