install/systemd: tglist-sync timer for follower boxes; INSTALL.md notes on systemd/cron

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

install/systemd/default-svxportal-tglist-sync

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+# Follower-box TG list sync (svxportal-tglist-sync.service/.timer).
+#
+# UPSTREAM = the master's public TG list URL. When set, this box is a FOLLOWER:
+# the timer pulls that list into DEST 4x/day and the web TG editor is hidden.
+# Leave UPSTREAM empty on the MASTER and on fully-standalone boxes — they own the
+# list locally and edit it in the web; the sync is then a no-op.
+UPSTREAM=https://svxportal.my.domain.com/tglist.php
+DEST=/etc/svxlink/tglist.json

install/systemd/svxportal-tglist-sync.service

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+[Unit]
+Description=Sync canonical TG list from svxportal master
+Documentation=file:/etc/svxlink/tglist-sync.sh
+Wants=network-online.target
+After=network-online.target
+
+[Service]
+Type=oneshot
+EnvironmentFile=/etc/default/svxportal-tglist-sync
+ExecStart=/bin/bash /etc/svxlink/tglist-sync.sh

install/systemd/svxportal-tglist-sync.timer

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+[Unit]
+Description=Sync canonical TG list from svxportal master (4x/day)
+
+[Timer]
+# Shortly after boot, then every 6 hours (00,06,12,18). Persistent catches a
+# missed run if the box was off at the scheduled time.
+OnBootSec=2min
+OnCalendar=*-*-* 00,06,12,18:00:00
+Persistent=true
+
+[Install]
+WantedBy=timers.target

install/systemd/tglist-sync.sh

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+#!/bin/bash
+# Follower-box sync of the canonical TG list.
+#
+# Pulls the master list from the svxportal master (its public /tglist.php) into
+# the LOCAL /etc/svxlink/tglist.json, so every local program reads ONE identical
+# list: svxdr (Lastheard TG name/Location) and the box's own /tglist.php (TG
+# Monitor) both read that local file. No extra daemon — a plain curl run by a
+# systemd timer.
+#
+# Master and fully-standalone boxes OWN the file locally (web editor) and must
+# NOT run this — leave UPSTREAM empty there (the timer is a no-op / not enabled).
+set -euo pipefail
+: "${UPSTREAM:=}"
+: "${DEST:=/etc/svxlink/tglist.json}"
+
+# Empty UPSTREAM = this box owns its list; nothing to sync.
+[ -n "$UPSTREAM" ] || { echo "UPSTREAM empty — this box owns its TG list, skipping sync"; exit 0; }
+
+tmp="$(mktemp)"; out="$(mktemp)"
+trap 'rm -f "$tmp" "$out"' EXIT
+
+curl -fsS -m 20 "$UPSTREAM" -o "$tmp"
+
+# Keep ONLY the canonical shape {tgs:[...],requests:[]}. Refuse to overwrite the
+# live file with anything that is not a valid list (a 404/HTML/partial body must
+# never blank the TG names) — last good copy then simply stays.
+python3 - "$tmp" "$out" <<'PY'
+import json, sys
+d = json.load(open(sys.argv[1]))
+tgs = d.get("tgs")
+if not isinstance(tgs, list) or not tgs:
+    raise SystemExit("upstream has no tgs list — refusing to overwrite")
+json.dump({"tgs": tgs, "requests": []}, open(sys.argv[2], "w"), indent=2)
+PY
+
+# www-data owns it so the web can still read it; atomic replace via install.
+install -o www-data -g www-data -m 0664 "$out" "$DEST"
+echo "TG list synced from $UPSTREAM -> $DEST"