d0b733f831
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Applied step 0 to production, backup first, IPv4 untouched throughout. vyos001 held the VIP and the internet the whole way; verified before and after every commit. Order, which is the safety property: he-secrets onto vyos002 -> vrrp-wan-install on BOTH (so the gate exists before the tunnel) -> tunnel + task-scheduler on vyos002 -> route6 + bond0.9 ::2 + router-advert on vyos002 -> link-mtu 1472 on vyos001. The blackhole is confirmed behaviour, not theory. The moment the tunnel committed, vyos002 brought tun0 UP with source 87.192.101.48 -- an address it does not own -- and the reconciler closed it on the next tick: vrrp-wan: not MASTER: bringing tun0 down vrrp-wan: not MASTER: stopping radvd (deprecates the v6 gateway) Same for radvd: VyOS started it on commit, the reconciler stopped it. Both have stayed shut. That is the override's old "it would simply stay down" assumption failing in production exactly as it failed in the sim. wan-drill --dry now reports the same tunnel source on both routers, where it previously read "<no tunnel -- IPv6 cannot survive a failover>". Two things found by deploying rather than reading: - commit-confirm hangs non-interactively here, exactly as PPPOE-HA.md records. The ssh timed out leaving an orphaned config-mgmt commit_confirm holding the config lock, with nothing committed. Killed it and used plain commit + save -- safe on the backup, which holds no VIPs, no WAN, and whose LoT path is untouched. Worth knowing the failure is clean: no partial config landed. - he-tunnel-follow's status path died with "WAN_MTU: bad array subscript" on the backup. An empty array subscript is a hard bash error, not an empty expansion, so the :- default never applies -- and a backup has no default route, so it broke on precisely the box whose state you most need to read. Fixed and redeployed to both. This is now live DRIFT against the Pulumi model. Until migration/pulumi-override-he-tunnel-both.json is merged into overrides.json, a pulumi up can strip the tunnel, route6, bond0.9 addresses, router-advert and task-scheduler entry. Recorded there and in the backlog's drift section. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01DMVzWZgiKW2wquf5z8S1yH
182 lines
8.5 KiB
Bash
Executable File
182 lines
8.5 KiB
Bash
Executable File
#!/bin/bash
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# Keep the Hurricane Electric 6in4 tunnel pointed at whichever WAN is live.
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#
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# The tunnel is anchored to a source IPv4. When failover moves the default route
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# from the 10 gig to PPPoE, 6in4 packets keep leaving with the old source, HE
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# drops them, and IPv6 goes dark while IPv4 keeps working -- a partial outage
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# that presents as "some sites are broken", which is far worse to diagnose than
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# a clean one.
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#
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# Installed on BOTH routers and gated on VRRP mastership: the backup exits
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# immediately, and vrrp-wan-reconcile brings tun0 up and calls this script the
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# moment it takes the VIP. The HE endpoint itself needs no update when the WAN
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# moves between routers -- 87.192.101.48 is the 10 gig lease bound to the cloned
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# MAC, so it follows the VIP to the other box unchanged (proven by the 2026-09-06
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# drill). HE only has to be told about the WITHIN-box fall back to PPPoE.
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#
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# Changes are made at KERNEL level (`ip tunnel change`), not in VyOS config, on
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# purpose:
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# - no commit per WAN flip, so a flapping line cannot churn the config;
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# - no drift against the Pulumi model, so `vyos-verify` stays meaningful;
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# - a reboot restores config.boot, which pins the 10 gig -- the correct
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# default -- so the wrong state cannot survive a restart.
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#
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# he-tunnel-follow status what is live vs what should be (read-only)
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# he-tunnel-follow run reconcile, updating HE if the source changed
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# he-tunnel-follow run --dry say what it would do, change nothing
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#
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# Credentials in /config/he-secrets (0600), NOT in git:
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# HE_USER=<tunnelbroker username>
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# HE_UPDATE_KEY=<from the tunnel's Advanced tab -- replaces the account password>
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# HE_TUNNEL_ID=<numeric tunnel id>
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set -uo pipefail
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TUNNEL="${TUNNEL:-tun0}"
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SECRETS="${SECRETS:-/config/he-secrets}"
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STATE="${STATE:-/run/he-tunnel-follow.state}"
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ROLE_STATE="${ROLE_STATE:-/run/he-tunnel-follow.role}"
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# HE's update endpoint, as a variable so labsim can point it at a stub. The sim
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# has no public IPv4 and no HE account, which is the whole reason the tunnel was
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# never rehearsed; with this the sim can exercise the HE-side half too.
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HE_UPDATE_URL="${HE_UPDATE_URL:-https://ipv4.tunnelbroker.net/nic/update}"
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# This script is installed on BOTH routers -- the same principle as the PPPoE
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# gate: configured identically everywhere, gated at runtime. So it must know
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# when it is the backup. Left ungated, the backup copy either dies on "no
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# default route" every minute, or, far worse, sees its own idle pppoe0 address
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# and points the HE endpoint at it. Vodafone hands out a different IPv4 on every
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# dial, so that is an IPv6 blackhole plus a wasted write against a rate-limited
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# API -- and it would fire on the backup, where nobody is looking.
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#
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# The VIP comes from the same /config/vrrp-wan.conf the reconciler and the
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# health check read, so there is exactly one definition of "master" on the box.
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WAN_CONF="${WAN_CONF:-/config/vrrp-wan.conf}"
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# shellcheck disable=SC1090
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[ -r "$WAN_CONF" ] && . "$WAN_CONF"
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VIP="${VRRP_WAN_VIP:-192.168.1.1}"
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# 6in4 costs 20 bytes. The 10 gig path is 1500 -> 1480; PPPoE is 1492 -> 1472.
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# Getting this wrong is the classic "IPv6 works until something large" failure.
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declare -A WAN_MTU=( ["bond0.53"]=1480 ["pppoe0"]=1472 )
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# Require the same answer twice before acting. HE rate-limits updates, and a
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# flapping WAN would otherwise hammer the API exactly when it is needed most.
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HYSTERESIS="${HYSTERESIS:-2}"
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log() { logger -t he-tunnel-follow -- "$*"; printf ' %s\n' "$*"; }
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die() { logger -t he-tunnel-follow -p user.err -- "$*"; printf ' ERROR: %s\n' "$*" >&2; exit 1; }
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holds_vip() { ip -4 -o addr show 2>/dev/null | grep -q " ${VIP}/"; }
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active_wan() { ip -4 route show default 2>/dev/null | awk '/^default/{for(i=1;i<=NF;i++) if($i=="dev") print $(i+1); exit}'; }
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addr_of() { ip -4 -br addr show "$1" 2>/dev/null | awk '{print $3}' | cut -d/ -f1; }
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tunnel_src() { ip tunnel show "$TUNNEL" 2>/dev/null | sed -nE 's/.* local ([0-9.]+).*/\1/p'; }
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tunnel_mtu() { cat "/sys/class/net/$TUNNEL/mtu" 2>/dev/null; }
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# HE's dyndns-style endpoint. `myip` is passed EXPLICITLY rather than letting HE
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# infer it from the request source: mid-failover the request itself may egress
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# either line, and inferring would happily point the tunnel at the WAN we just
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# left.
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he_update() {
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local ip="$1"
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[ -r "$SECRETS" ] || die "no $SECRETS -- create it with HE_USER / HE_UPDATE_KEY / HE_TUNNEL_ID (0600)"
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# shellcheck disable=SC1090
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. "$SECRETS"
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[ -n "${HE_USER:-}" ] && [ -n "${HE_UPDATE_KEY:-}" ] && [ -n "${HE_TUNNEL_ID:-}" ] \
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|| die "$SECRETS is missing HE_USER, HE_UPDATE_KEY or HE_TUNNEL_ID"
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local out
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out="$(curl -sS --max-time 25 \
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--data-urlencode "username=$HE_USER" \
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--data-urlencode "password=$HE_UPDATE_KEY" \
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--data-urlencode "hostname=$HE_TUNNEL_ID" \
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--data-urlencode "myip=$ip" \
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"$HE_UPDATE_URL" 2>&1)"
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# dyndns protocol: "good <ip>" or "nochg <ip>" are both success.
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case "$out" in
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good*|nochg*) log "HE endpoint set to $ip ($out)"; return 0 ;;
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*) die "HE update refused: $out" ;;
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esac
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}
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# Log only when the role CHANGES. On a 1-minute timer an unconditional line
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# would be 1440 entries a day on the backup, which is how a real message gets
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# lost. The marker lives in /run, so a reboot re-announces the role once.
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note_role() {
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local role="$1" last=""
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[ -r "$ROLE_STATE" ] && read -r last < "$ROLE_STATE"
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[ "$last" = "$role" ] && return 0
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echo "$role" > "$ROLE_STATE"
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log "role is now $role"
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}
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reconcile() {
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local dry="${1:-}"
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local wan src want_mtu cur_src cur_mtu
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# The backup owns nothing here. vrrp-wan-reconcile holds tun0 down on this box
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# and will run this script itself the moment it takes the VIP, so there is
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# nothing to do and nothing to say.
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if ! holds_vip; then
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note_role backup
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rm -f "$STATE" # start a promoted box with a clean hysteresis count
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return 0
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fi
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note_role master
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wan="$(active_wan)"; [ -n "$wan" ] || die "no default route; refusing to guess"
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src="$(addr_of "$wan")"; [ -n "$src" ] || die "no IPv4 address on $wan"
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want_mtu="${WAN_MTU[$wan]:-}"
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[ -n "$want_mtu" ] || die "unknown WAN '$wan' -- add it to WAN_MTU rather than guessing an MTU"
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cur_src="$(tunnel_src)"; cur_mtu="$(tunnel_mtu)"
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if [ "$cur_src" = "$src" ] && [ "$cur_mtu" = "$want_mtu" ]; then
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rm -f "$STATE"
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log "in sync: $TUNNEL via $wan src $src mtu $cur_mtu"
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return 0
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fi
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# Hysteresis: count consecutive runs agreeing on the same target.
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local seen=0 last=""
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[ -r "$STATE" ] && { read -r last seen < "$STATE"; }
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if [ "$last" = "$src" ]; then seen=$((seen + 1)); else seen=1; fi
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echo "$src $seen" > "$STATE"
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if [ "$seen" -lt "$HYSTERESIS" ]; then
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log "change seen ($cur_src -> $src) but waiting for stability ($seen/$HYSTERESIS)"
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return 0
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fi
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if [ "$dry" = "--dry" ]; then
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log "DRY RUN: would set HE endpoint to $src, then $TUNNEL local $src mtu $want_mtu"
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return 0
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fi
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# HE first, then local. Either order costs a brief drop, but changing locally
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# first guarantees HE discards our packets for the whole window.
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he_update "$src" || return 1
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sudo ip tunnel change "$TUNNEL" mode sit local "$src" || die "failed to set tunnel local address"
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sudo ip link set "$TUNNEL" mtu "$want_mtu" || die "failed to set tunnel MTU"
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rm -f "$STATE"
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log "moved $TUNNEL to $wan: src $cur_src -> $src, mtu $cur_mtu -> $want_mtu"
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}
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case "${1:-status}" in
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status)
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wan="$(active_wan)"
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printf ' role : %s (vip %s)\n' "$(holds_vip && echo master || echo backup)" "$VIP"
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printf ' active WAN : %s\n' "${wan:-<none>}"
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printf ' wan addr : %s\n' "$(addr_of "${wan:-lo}")"
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printf ' tunnel : %s\n' "$(ip -br link show "$TUNNEL" 2>/dev/null | awk '{print $2}' || echo '<absent>')"
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printf ' tunnel src : %s\n' "$(tunnel_src)"
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# `${WAN_MTU[$wan]}` with an EMPTY subscript is a hard bash error --
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# "bad array subscript" -- not an empty expansion, and the :- default never
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# gets a chance to apply. A backup router has no default route, so `wan` is
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# empty there and `status` printed an error line on exactly the box whose
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# state you most need to read. Only index the array once there is a key.
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printf ' tunnel mtu : %s (want %s)\n' "$(tunnel_mtu)" \
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"$([ -n "${wan:-}" ] && echo "${WAN_MTU[$wan]:-?}" || echo '- (no WAN; this box is not master)')"
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printf ' he endpoint: %s\n' "$HE_UPDATE_URL"
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[ -r "$SECRETS" ] && printf ' credentials: present\n' || printf ' credentials: MISSING (%s)\n' "$SECRETS"
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;;
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run) reconcile "${2:-}" ;;
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*) die "usage: he-tunnel-follow {status|run [--dry]}" ;;
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esac
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