[glm-grade=B+] ops: self-healing watchdog for DNS2 (container, port 3001, Caddyfile, caddy)
30s systemd timer heals four real failure classes: container down (docker start -> start.sh fallback), rogue host process on :3001, Caddyfile wiped by foreign generators (known-good snapshot + size/site-block/marker gates), caddy down/not serving. Telegram alerts with 15-min per-class cooldown; stamp only burned on successful send. Adversarial review B- (both blockers fixed: snapshot poisoning via multi-gate integrity + refresh lockout, deployment). Live kill-tested twice: full recovery in one cycle, alerts delivered, cooldown verified.
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Krystie
Executable
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#!/bin/bash
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# /usr/local/bin/dashcaddy-watchdog — self-healing guard for DashCaddy on DNS2.
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#
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# Heals four failure classes that have actually knocked DashCaddy down:
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# 1. Container down/unhealthy/removed -> docker start / bash start.sh
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# 2. Rogue host node process stealing :3001 -> kill it, restart container
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# 3. Caddyfile wiped by a foreign generator -> restore known-good, restart caddy
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# 4. Caddy down or not serving -> restart caddy
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#
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# Runs from dashcaddy-watchdog.service (systemd timer, every 30s) or manually.
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# Alerts go to Telegram (Sami) on every corrective action; rate-limited per
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# action class (default 15 min) to avoid spam during flapping. All state in
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# /var/lib/dashcaddy-watchdog/ so restarts of the watchdog never flap.
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#
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# Exit codes: 0 = healthy or healed cleanly. Healing never exits non-zero —
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# a permanently-failed unit would pollute systemctl --failed monitoring.
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set -u
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CONTAINER="dashcaddy-api"
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START_SH="/opt/dashcaddy/start.sh"
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CADDYFILE="/etc/caddy/Caddyfile"
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KNOWN_GOOD="/var/lib/dashcaddy-watchdog/known-good-Caddyfile"
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STATE_DIR="/var/lib/dashcaddy-watchdog"
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LOG="/var/log/dashcaddy-watchdog.log"
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ALERT_COOLDOWN=$((15 * 60)) # seconds between alerts of the same class
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LOG_MAX=1048576 # 1 MiB
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# Caddyfile integrity gates (adversarial review: markers alone can be
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# satisfied by a damaged file). Size floor excludes the 4952-byte foreign-
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# generator file from the 2026-08-13 incident; service-block floor excludes
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# marker-duplication damage.
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CADDYFILE_MIN_BYTES=10000
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CADDYFILE_MIN_SITES=10
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mkdir -p "$STATE_DIR"
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touch "$LOG"
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log() { echo "$(date -u +%Y-%m-%dT%H:%M:%SZ) $*" >> "$LOG"; }
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# --- Telegram alerting (best-effort; a notify failure never blocks healing) ---
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notify() { # notify <class> <message>
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local class="$1" msg="$2"
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local now last elapsed
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now=$(date +%s)
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local stamp="$STATE_DIR/alert-$class"
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if [ -f "$stamp" ]; then
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last=$(cat "$stamp" 2>/dev/null | tr -cd '0-9')
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last="${last:-0}"
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elapsed=$(( now - last ))
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if [ "$elapsed" -lt "$ALERT_COOLDOWN" ]; then
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log "ALERT-SUPPRESSED class=$class (${elapsed}s < ${ALERT_COOLDOWN}s)"
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return 0
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fi
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fi
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local token chat sent
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token=$(grep -E '^HERMES_ENV_TELEGRAM_BOT_TOKEN=' /root/.hermes/.env | head -1 | cut -d= -f2-)
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chat="637130179"
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if [ -z "$token" ]; then
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log "ALERT-NO-TOKEN class=$class msg=$msg"
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return 0
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fi
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sent=$(curl -s -m 10 -X POST "https://api.telegram.org/bot${token}/sendMessage" \
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-d chat_id="$chat" -d text="🛡️ DashCaddy watchdog (DNS2): $msg" \
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2>/dev/null | grep -c '"ok":true')
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if [ "${sent:-0}" -ge 1 ]; then
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date +%s > "$stamp"
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log "ALERT-SENT class=$class msg=$msg"
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else
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log "ALERT-SEND-FAILED class=$class (cooldown NOT burned)"
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fi
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}
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log_rotate() {
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[ -f "$LOG" ] || return 0
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local size
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size=$(stat -c%s "$LOG" 2>/dev/null || echo 0)
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if [ "$size" -gt "$LOG_MAX" ]; then
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tail -c $((LOG_MAX / 2)) "$LOG" > "${LOG}.tmp" && mv "${LOG}.tmp" "$LOG"
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fi
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}
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# --- Health probes -----------------------------------------------------------
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container_running() {
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docker ps --filter "name=^${CONTAINER}$" --format '{{.Names}}' 2>/dev/null | grep -q "^${CONTAINER}$"
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}
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container_healthy() {
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local st started age
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st=$(docker inspect -f '{{.State.Health.Status}}' "$CONTAINER" 2>/dev/null) || return 1
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if [ "$st" = "healthy" ]; then return 0; fi
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if [ "$st" = "starting" ]; then
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# Max-starting-age guard (adversarial review): never park forever on a
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# container stuck in 'starting'. StartPeriod is 10s; allow 90s slack.
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started=$(docker inspect -f '{{.State.StartedAt}}' "$CONTAINER" 2>/dev/null)
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age=$(( $(date +%s) - $(date -d "${started:-1970-01-01}" +%s 2>/dev/null || echo 0) ))
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[ "$age" -le 90 ]
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return
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fi
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return 1
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}
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rogue_on_port() {
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# any listener on 127.0.0.1:3001 that is NOT docker-proxy
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ss -H -tlnp 'sport = :3001' 2>/dev/null | grep -v docker-proxy | grep -q .
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}
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caddy_up() {
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systemctl is-active --quiet caddy
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}
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caddy_serving() {
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# status.sami via loopback; internal CA cert -> -k
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curl -sk -m 8 -o /dev/null -w '%{http_code}' --resolve status.sami:443:127.0.0.1 https://status.sami/ 2>/dev/null | grep -qE '^[23]'
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}
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caddyfile_intact() {
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# Integrity gates (adversarial review hardened): markers + size floor +
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# service-block floor + caddy syntax validation.
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[ -f "$CADDYFILE" ] || return 1
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local refs ca bytes sites
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refs=$(grep -c 'dashcaddy_auth' "$CADDYFILE" 2>/dev/null || echo 0)
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ca=$(grep -c 'sami-ca' "$CADDYFILE" 2>/dev/null || echo 0)
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bytes=$(stat -c%s "$CADDYFILE" 2>/dev/null || echo 0)
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sites=$(grep -cE '^[a-z0-9.-]+\.(sami|net|com|me|org)[^a-z0-9-]*\{$' "$CADDYFILE" 2>/dev/null || echo 0)
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[ "$refs" -ge 8 ] && [ "$ca" -ge 1 ] && [ "$bytes" -ge "$CADDYFILE_MIN_BYTES" ] && [ "$sites" -ge "$CADDYFILE_MIN_SITES" ]
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}
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refresh_known_good() {
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# Refuse to refresh within 10 minutes of a caddyfile heal (prevents the
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# partial-write / post-heal window from poisoning the snapshot).
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local heal_stamp="$STATE_DIR/last-caddyfile-heal"
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if [ -f "$heal_stamp" ]; then
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local since=$(( $(date +%s) - $(cat "$heal_stamp" | tr -cd '0-9' || echo 0) ))
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if [ "$since" -lt 600 ]; then
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return 0
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fi
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fi
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if caddyfile_intact; then
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if [ -f "$KNOWN_GOOD" ] && cmp -s "$CADDYFILE" "$KNOWN_GOOD"; then
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return 0 # unchanged — keep existing snapshot (preserves mtime)
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fi
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cp -a "$CADDYFILE" "$KNOWN_GOOD"
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log "KNOWN-GOOD refreshed ($(stat -c%s "$KNOWN_GOOD" 2>/dev/null || echo '?') bytes)"
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fi
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}
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# --- Remediation --------------------------------------------------------------
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heal_container_start() {
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log "HEAL container-start"
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docker start "$CONTAINER" >/dev/null 2>&1
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if ! container_running; then
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log "HEAL container-start failed; falling back to start.sh"
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bash "$START_SH" >> "$LOG" 2>&1
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fi
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notify container "container was down — restarted it"
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}
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heal_container_recreate() {
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log "HEAL container-recreate (start.sh)"
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bash "$START_SH" >> "$LOG" 2>&1
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notify container "container unhealthy — recreated via start.sh"
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}
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heal_rogue_port() {
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local pids
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pids=$(ss -H -tlnp 'sport = :3001' 2>/dev/null | grep -v docker-proxy | grep -oP 'pid=\K[0-9]+' | sort -u)
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log "HEAL rogue-port pids=$pids"
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for pid in $pids; do
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[ "$pid" = "$$" ] && continue
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local cmdline
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cmdline=$(cat /proc/$pid/cmdline 2>/dev/null | tr '\0' ' ')
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case "$cmdline" in
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*docker-proxy*|*dashcaddy-watchdog*) continue ;;
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esac
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# PID recycling guard: the process must still be listening on :3001
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if ! ss -H -tlnp 'sport = :3001' 2>/dev/null | grep -q "pid=$pid"; then
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continue
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fi
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log "KILL pid=$pid cmd=$cmdline"
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kill "$pid" 2>/dev/null || true
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done
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sleep 3
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ss -H -tlnp 'sport = :3001' | grep -q docker-proxy || docker restart "$CONTAINER" >/dev/null 2>&1
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notify rogue-port "rogue host process was holding port 3001 — killed it, container restarted"
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}
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heal_caddyfile() {
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log "HEAL caddyfile-restore"
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if [ -f "$KNOWN_GOOD" ]; then
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cp -a "$KNOWN_GOOD" "$CADDYFILE"
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chown caddy:caddy "$CADDYFILE" 2>/dev/null || true
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systemctl restart caddy
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notify caddyfile "Caddyfile was wiped/overwritten by a foreign generator — restored known-good and restarted Caddy"
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else
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notify caddyfile "Caddyfile damaged and no known-good snapshot exists — MANUAL ACTION NEEDED"
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fi
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# Post-heal grace stamp: caddy_serving() skipped for 60s after this point.
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date +%s > "$STATE_DIR/last-caddyfile-heal"
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}
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heal_caddy_down() {
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log "HEAL caddy-restart"
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systemctl restart caddy
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notify caddy "caddy was down — restarted it"
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}
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heal_caddy_5xx() {
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log "HEAL caddy-5xx"
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systemctl restart caddy
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notify caddy "caddy was not serving status.sami (non-2xx/3xx) — restarted it"
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}
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# --- Main ----------------------------------------------------------------------
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log_rotate
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ACTION_TAKEN=0
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# 0. Maintain known-good Caddyfile snapshot whenever current file is intact.
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refresh_known_good
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# 3. Caddyfile integrity (before caddy health so restore happens first).
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if ! caddyfile_intact && [ -f "$KNOWN_GOOD" ]; then
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heal_caddyfile
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ACTION_TAKEN=1
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fi
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# 4. Caddy up + serving
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if ! caddy_up; then
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heal_caddy_down
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ACTION_TAKEN=1
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fi
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if ! caddy_serving; then
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# Skip if we JUST restarted caddy this cycle (post-heal grace).
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if [ -f "$STATE_DIR/last-caddyfile-heal" ]; then
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local_grace=$(( $(date +%s) - $(cat "$STATE_DIR/last-caddyfile-heal" | tr -cd '0-9' || echo 0) ))
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if [ "$local_grace" -lt 60 ]; then
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log "caddy_serving skipped (post-caddyfile-heal grace ${local_grace}s)"
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else
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heal_caddy_5xx
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ACTION_TAKEN=1
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fi
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else
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heal_caddy_5xx
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ACTION_TAKEN=1
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fi
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fi
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# 2. Rogue host process on :3001
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if rogue_on_port; then
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heal_rogue_port
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ACTION_TAKEN=1
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fi
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# 1. Container down/unhealthy (last: start.sh recreates and re-binds 3001)
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if ! container_running; then
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heal_container_start
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ACTION_TAKEN=1
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elif ! container_healthy; then
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heal_container_recreate
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ACTION_TAKEN=1
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fi
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if [ "$ACTION_TAKEN" = "1" ]; then
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log "cycle complete: corrective action taken"
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else
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log "cycle complete: healthy"
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fi
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exit 0
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@@ -0,0 +1,11 @@
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[Unit]
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Description=DashCaddy self-healing watchdog (container, port 3001, Caddyfile, caddy)
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After=docker.service network-online.target
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Wants=network-online.target
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[Service]
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Type=oneshot
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ExecStart=/usr/local/bin/dashcaddy-watchdog
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TimeoutStartSec=90
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StandardOutput=journal
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StandardError=journal
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@@ -0,0 +1,10 @@
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[Unit]
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Description=Run DashCaddy watchdog every 30 seconds
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[Timer]
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OnBootSec=2min
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OnUnitActiveSec=30s
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AccuracySec=5s
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[Install]
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WantedBy=timers.target
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