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home-network-k3s-impl/apps
jakman85andClaude Opus 5 fda5c31a94
gate / gate (pull_request) Successful in 1m56s
gate / conformance (pull_request) Has been skipped
fix(pihole): make the split-horizon answer cacheable, or one blip latches the WAN IP for 5 minutes
Operator reported DNS flapping between the cluster ingress and the router's
public IP. PiHole is not at fault -- both replicas answer 192.168.2.20
consistently (6/6 via the VIP, 8/8 from a client). The bug is an asymmetry in
CACHEABILITY that we created. Measured:

  pihole  192.168.2.23 -> 192.168.2.20               TTL=0
  public  1.1.1.1      -> wan.home.keithjackson.dev  TTL=300
  router  192.168.2.1  -> wan....  TTL=153 -> 148 -> 143   (decrementing = caching)

dnsmasq answers `address=` entries with TTL 0 unless told otherwise. The router
forwards LAN queries to PiHole and caches the result, so the CORRECT answer is
uncacheable -- re-queried on every lookup, maximum exposure to any gap -- while
the WRONG answer caches for 300s. The instant the router falls back to upstream
(standard forwarder behaviour when the target does not answer) it latches the
WAN address for the whole LAN for five minutes, then expires, re-queries PiHole,
gets TTL 0, and is immediately re-exposed.

So ONE sub-second PiHole gap -- pod restart, L2 lease move, ARP flap, kured
reboot -- becomes FIVE MINUTES of the house resolving to the WAN IP. That
asymmetry, not the gap, is why it reads as "flapping".

Fix: local-ttl=60 prepended to FTLCONF_misc_dnsmasq_lines. dnsmasq applies
local-ttl to replies made from configuration, so one directive covers all five
address= names. 60s rides out a pod restart and a lease re-election while a real
VIP change still propagates inside a minute; these VIPs are pinned and static.

apps/wave-0/pihole.yaml regenerated with the canonical render command
(--all catalog -o apps --wave-layout --no-image-automation, NOT --emit-waves);
exactly two files changed and the rendered diff is the single local-ttl prefix.

UNAPPLIED. Does NOT remove the trigger: .23 still has two independently-elected
L2 leases (as do crafty .22 and unifi .21), which the operator has parked. If
the TTL is still 0 after merge, suspect FTL silently rejecting the passthrough
line -- see the handoff.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
2026-10-18 02:56:49 -05:00
..
2026-09-19 02:49:16 +00:00

apps

App-tier manifests, rendered from catalog/*.yaml ServiceDefinitions by catalog/render.py and split into dependency-ordered waves (wave-<N>/).

  • Each wave-<N>/ is reconciled by its own Flux Kustomization apps-wave-<N> (clusters/base/apps-wave-<N>.yaml), which dependsOn wave N-1 (wave 0 dependsOn platform-config) and health-gates (wait: true) ONLY that wave. A crashlooping workload in a later wave can no longer stall an earlier wave or block new revisions.
  • wave-<N>/kustomization.yaml and clusters/base/apps-wave-<N>.yaml are generated — run python3 catalog/render.py --emit-waves after onboarding a service; do not hand-edit them.
  • Wave assignment = longest dependency-path depth over the catalog dependencies: graph; a co-located CNPG database <svc>-db is a leaf and always lands strictly below its consumer.

See ../DESIGN-waves.md for the wave table, Flux topology, and the cutover runbook.