diff --git a/persistent-memory.d/2026-09-15-fv-mesh-watchdog.md b/persistent-memory.d/2026-09-15-fv-mesh-watchdog.md index 2733dd5..cdc01e7 100644 --- a/persistent-memory.d/2026-09-15-fv-mesh-watchdog.md +++ b/persistent-memory.d/2026-09-15-fv-mesh-watchdog.md @@ -1,4 +1,4 @@ -# `[2026-09-15]` Dead man's switch on fv-ml1 — mesh watchdog +# `[2026-09-15]` Break-glass mesh path on fv-ml1 (inverted from a restore-watchdog) Every path into Fountain Valley runs through equipment at FV. When fv-ml1 loses its way back to the fleet there is no console, no local hands, and the BMC sits @@ -40,3 +40,42 @@ it from its own LAN: it accepted `10.251.0.0/16` from the gateway — **its own subnet** — and routed the local network through the tunnel. Recovery only worked because its mesh address happened to still answer. Same family as the 2026-09-06 nh3-dev incident; see [[2026-09-15-fv-cross-site-snat]]. + +## ⭐ INVERTED the same night, on the operator's suggestion + +The first version kept fv-ml1 permanently on the mesh and restored its Tailscale +state when it broke. Once the FV SNAT rules landed +([[2026-09-15-fv-cross-site-snat]]) that membership became **redundant for +routing** — its only remaining value was as a second way in. The operator's +question was the better design: *keep the box OFF the mesh and have the watchdog +JOIN when it loses the fleet.* Same recovery path, no standing second door. + + normal tailscaled stopped + disabled; fleet reached via the gateway SNAT + fault FLEET_ANCHORS (nh3-dev, nh3-docker) unreachable while the WAN is up + action start tailscaled + `tailscale up` -> reachable at its 100.64.x address + +**Verified end to end, off-mesh:** fv-ml1 removed from headscale entirely, then +confirmed it still reaches NH3/ESH/ANA/IRV/internet on the SNAT path alone; then +the break-glass fired on cue (counted 1..4, joined at 5 as `100.64.0.10`), +answered ping **and ssh** from nh3-dev, and was closed again cleanly. + +⚠ **No auto-leave, deliberately.** Once open the door stays open until a human +runs `systemctl disable --now tailscaled`. A watchdog that re-closes on recovery +flaps, and a flapping recovery path is down exactly when someone finally looks. + +⚠ **Skipped if already on the mesh** — that is what makes it idempotent after +firing, rather than re-running `tailscale up` every minute. + +### The hole the operator's question exposed + +The stored rejoin key was `hskey-auth-g8_iQtwSHntv`, one of the 2026-09-12 FV +cutover keys — **expiring 2026-09-19**. A break-glass credential that dies in +four days and fails silently at the only moment it matters. Replaced with a +dedicated **1-year reusable** key (headscale ID 8, expires 2027-09-15), vaulted +as `fv-ml1/headscale-breakglass-key`, stored `root:600` at +`/var/lib/fv-mesh-watchdog/authkey`. + +⭐ That also **closes** the standing self-join risk rather than trading it: the +two stale reusable keys (IDs 5, 6) were expired, so the mesh now has exactly one +live reusable key, purpose-built, on a host we control — instead of two orphans +nobody owned. diff --git a/persistent-memory.md b/persistent-memory.md index d1f1987..33a57a2 100644 --- a/persistent-memory.md +++ b/persistent-memory.md @@ -127,9 +127,9 @@ on the FV gateway, all `src=10.251.50.0/24`, dst `10.100.0.0/16` / `10.0.0.0/16` Anaheim only. Commits `fa04f45`, `0ab9da5`. ### Safety net at FV -- **Dead man's switch on fv-ml1** — `fv-mesh-watchdog` timer, 1/min, two independent - anchors, restores known-good Tailscale after 5 consecutive mesh-only failures, no-ops - when the WAN anchor is also down. Proven by positive control. `8c8559b`. +- **Break-glass mesh path on fv-ml1** — the box is now OFF the mesh; `fv-mesh-watchdog` + (1/min) JOINS it when nh3-dev/nh3-docker go unreachable while the WAN is up. Verified + end to end off-mesh: joined as `100.64.0.10`, answered ping+ssh, closed cleanly. - **FV firewall config in the nightly restic run** via ana-docker's pre-backup hook (`80d982d`); `infra-ops` now has an SSH key + `/bin/sh` on the gateway, so the allowlisted WAN path gives a shell rather than API-only. @@ -142,12 +142,12 @@ from the mesh at its LAN address (`9dbd829`); ESPHome pinned/relocated/rotated (`d1769ed` ff); `kb` KB-search tool shipped (`68fa80f`). ### Open loose ends (none blocking) -- **nh3-dev is still a bare mesh member.** Operator authorized retiring both it and - fv-ml1 from the mesh; fv-ml1 turned out **load-bearing** (removing it cut FV off from - NH3/ESH) and was restored as `100.64.0.9`. nh3-dev was never touched. Now that the - SNAT fix exists the original rationale may hold again — **unexecuted, operator's call.** -- **Two reusable headscale pre-auth keys** (IDs 5, 6) live until **2026-09-19** — the one - credential shape that lets an unknown device self-join. Vaulted, unused, FV cutover done. +- **nh3-dev is still a bare mesh member** — retirement authorized, never executed. + **Operator's call.** (fv-ml1 IS now retired: off-mesh, node record deleted, reaching the + fleet on the gateway's SNAT alone, with break-glass rejoin as its safety net.) +- ✅ **Stale reusable pre-auth keys retired** (IDs 5, 6 expired). The mesh now has exactly + one live reusable key: the dedicated fv-ml1 break-glass key, ID 8, expires 2027-09-15, + vaulted `fv-ml1/headscale-breakglass-key`. - **FV WAN admin is plain HTTP**, no TLS. Allowlisted to ESH/ANA/NH3 egress — ⚠ pinned to **egress IPs**, so a WAN change at any site silently removes the fallback. - **Legacy `/32` ANA NAT rule** redundant and invisible to `source_nat/search_rule`; @@ -161,7 +161,7 @@ from the mesh at its LAN address (`9dbd829`); ESPHome pinned/relocated/rotated - `[2026-09-15]` **FV cross-site routing fixed — one OPNsense outbound-NAT rule had been scoped to Anaheim only.** fv-ml1 now reaches NH3/ESH/IRV/ANA/mesh/internet; four rules, all `src=10.251.50.0/24`. The diagnostic signature is the valuable part: every layer looks correct and the discriminator is that *every other site pair works*. → `persistent-memory.d/2026-09-15-fv-cross-site-snat.md` -- `[2026-09-15]` **Dead man's switch on fv-ml1** — mesh watchdog, two independent anchors, deliberately no-ops when the uplink itself is down. Proven by positive control, not assumed. → `persistent-memory.d/2026-09-15-fv-mesh-watchdog.md` +- `[2026-09-15]` **Break-glass mesh path on fv-ml1** — inverted from a restore-watchdog on the operator's suggestion: the box is OFF the mesh and the watchdog JOINS it on fleet loss. Exposed a rejoin key expiring in 4 days; replaced with a dedicated 1-year key and the two stale reusable keys retired. → `persistent-memory.d/2026-09-15-fv-mesh-watchdog.md` - `[2026-09-15]` **Fleet identity/group/path conventions pinned + docker trees → `root:docker 2775` setgid on 5 hosts.** `svc-*` in 800-849, infra-ops 850, docker 851, `vh` for new hosts with no retro-renames; `0777` cleared; `linus` deleted; `llmuser` de-privileged. → `persistent-memory.d/2026-09-15-fleet-identity-conventions.md` diff --git a/servers/fv-ml1/fv-mesh-watchdog.sh b/servers/fv-ml1/fv-mesh-watchdog.sh index 34a14c0..9e3aa71 100644 --- a/servers/fv-ml1/fv-mesh-watchdog.sh +++ b/servers/fv-ml1/fv-mesh-watchdog.sh @@ -1,26 +1,38 @@ #!/bin/sh -# fv-mesh-watchdog — restore fv-ml1's mesh connectivity if a change strands it. +# fv-mesh-watchdog — BREAK-GLASS: join the mesh when fv-ml1 loses the fleet. # -# WHY: every path into the Fountain Valley site runs through equipment at FV. -# When fv-ml1 loses its way back to the fleet there is no console, no local -# hands, and the BMC sits behind the same gateway. On 2026-09-14 a -# `tailscale up --accept-routes` black-holed this box from its own LAN: it -# accepted 10.251.0.0/16 from the gateway — its OWN subnet — and started routing -# the local network through the tunnel. Recovery needed its mesh address, which -# only happened to still work. +# ⭐ INVERTED DESIGN (operator, 2026-09-15). fv-ml1 is normally OFF the mesh: its +# cross-site traffic is carried by outbound SNAT on the FV OPNsense gateway +# (docs/runbooks/fv-to-ana-nat.md), so mesh membership is redundant for routing +# and its only value is as a SECOND way in when the first one breaks. Keeping it +# permanently enrolled bought a standing second door; joining ON DEMAND buys the +# same recovery path without one. # -# WHAT IT DOES: probes two INDEPENDENT anchors once a minute. After -# FAIL_THRESHOLD consecutive failures it puts Tailscale back to known-good: -# accept-routes off, re-up against headscale. It touches nothing else — not -# routes, not firewall, not services — because a watchdog with a wide remit is -# a second way to lose the box. +# This is therefore not a "restore Tailscale" watchdog. It is a door that opens +# when the normal path is gone. # -# ⚠ Two anchors on purpose, and they must not share a failure mode: -# WAN_ANCHOR plain internet, no mesh involved -# MESH_ANCHOR a fleet address only reachable if the mesh works -# If only the mesh anchor fails, the mesh is the problem and we act. If BOTH -# fail the site's uplink is down and Tailscale cannot fix that, so we do NOT -# act — thrashing tailscaled during an ISP outage turns a wait into an incident. +# normal tailscaled stopped+disabled; fleet reached via the gateway's SNAT +# fault FLEET_ANCHORS unreachable while the WAN is up +# action start tailscaled and `tailscale up` -> the box is reachable at its +# mesh address even though its LAN path is broken +# +# ⚠ TWO ANCHOR CLASSES, and they must not share a failure mode: +# WAN_ANCHOR plain internet. If THIS is down the site uplink is gone, +# Tailscale cannot fix it, and we do nothing -- thrashing +# during an ISP outage turns a wait into an incident. +# FLEET_ANCHORS hosts reachable ONLY through the gateway's SNAT path. Their +# loss is exactly the fault this exists for. +# +# ⚠⚠ THE REJOIN MUST USE --accept-routes=false. On 2026-09-14 a +# `tailscale up --accept-routes` on this box accepted 10.251.0.0/16 from the +# gateway -- its OWN subnet -- and routed the local network through the tunnel, +# black-holing it. That happened with a human watching. Here it would run +# unattended, during an incident, on a box already in trouble. +# +# ⚠ NO AUTO-LEAVE. Once the door is open it stays open until a human closes it +# (`systemctl disable --now tailscaled`). A watchdog that re-closes on recovery +# flaps, and a flapping recovery path is worse than none -- it would be down +# exactly when someone finally looked. # # Disable for planned work: touch /etc/fv-watchdog.disable @@ -30,7 +42,7 @@ CONF=/etc/fv-mesh-watchdog.conf DISABLE=/etc/fv-watchdog.disable FAIL_THRESHOLD=5 WAN_ANCHOR=1.1.1.1 -MESH_ANCHOR=100.64.0.1 +FLEET_ANCHORS="10.100.10.50 10.100.50.40" # nh3-dev, nh3-docker LOGIN_SERVER=https://headscale.phasefinal.com [ -r "$CONF" ] && . "$CONF" @@ -41,34 +53,42 @@ mkdir -p "$STATE"; COUNT_FILE="$STATE/consecutive_failures" [ -f "$COUNT_FILE" ] || echo 0 > "$COUNT_FILE" count=$(cat "$COUNT_FILE" 2>/dev/null || echo 0) -ping -c 2 -W 3 "$WAN_ANCHOR" >/dev/null 2>&1 && wan=up || wan=down -ping -c 2 -W 3 "$MESH_ANCHOR" >/dev/null 2>&1 && mesh=up || mesh=down +# Already on the mesh? Then the door is open and there is nothing to do. This is +# also what makes the script idempotent after it has fired. +if [ "$(systemctl is-active tailscaled 2>/dev/null)" = active ] \ + && tailscale status >/dev/null 2>&1; then + [ "$count" -ne 0 ] && echo 0 > "$COUNT_FILE" + exit 0 +fi +ping -c 2 -W 3 "$WAN_ANCHOR" >/dev/null 2>&1 && wan=up || wan=down if [ "$wan" = down ]; then - # Uplink is down. Tailscale cannot fix that and restarting it during an ISP - # outage only adds churn. Reset the counter so the mesh timer starts clean - # once the site is back. - [ "$count" -ne 0 ] && log "uplink down (wan=$wan mesh=$mesh) — not a mesh fault, counter reset" + [ "$count" -ne 0 ] && log "uplink down — not a fleet-path fault, counter reset" echo 0 > "$COUNT_FILE"; exit 0 fi -if [ "$mesh" = up ]; then - [ "$count" -ne 0 ] && log "mesh recovered after $count failure(s)" +# Any fleet anchor answering means the normal path works. +fleet=down +for a in $FLEET_ANCHORS; do + if ping -c 2 -W 3 "$a" >/dev/null 2>&1; then fleet=up; break; fi +done + +if [ "$fleet" = up ]; then + [ "$count" -ne 0 ] && log "fleet path recovered after $count failure(s)" echo 0 > "$COUNT_FILE"; exit 0 fi count=$((count + 1)); echo "$count" > "$COUNT_FILE" -log "mesh anchor $MESH_ANCHOR unreachable while WAN is up ($count/$FAIL_THRESHOLD)" +log "fleet unreachable via the gateway path while WAN is up ($count/$FAIL_THRESHOLD) — anchors: $FLEET_ANCHORS" [ "$count" -lt "$FAIL_THRESHOLD" ] && exit 0 -log "THRESHOLD REACHED — restoring known-good Tailscale state" +log "THRESHOLD REACHED — opening the break-glass mesh path" echo 0 > "$COUNT_FILE" -tailscale set --accept-routes=false 2>&1 | while read -r l; do log " set: $l"; done +systemctl start tailscaled 2>&1 | while read -r l; do log " start: $l"; done if [ -r "$STATE/authkey" ]; then tailscale up --login-server "$LOGIN_SERVER" --authkey "$(cat "$STATE/authkey")" \ --accept-routes=false --hostname "$(hostname -s)" 2>&1 | while read -r l; do log " up: $l"; done + log "mesh path OPEN — reach this host at its 100.64.x address; close with 'systemctl disable --now tailscaled'" else - log " no $STATE/authkey — cannot re-register; tried accept-routes=false only" + log " NO $STATE/authkey — cannot join. The break-glass path is UNARMED." fi -systemctl restart tailscaled 2>&1 | while read -r l; do log " restart: $l"; done -log "restore attempt complete"