Add --no-html flag and Synology Task Scheduler setup

--no-html skips dashboard generation for deployments where river.php
reads the SQLite DB directly. synology-task.sh is a ready-to-configure
wrapper for DSM Task Scheduler.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

river_monitor.py

@@ -437,7 +437,7 @@ def load_or_create_config(args: argparse.Namespace, session: requests.Session) -
 # Main
 # --------------------------------------------------------------------------
 
-def poll_once(cfg: dict, session: requests.Session, verbose: bool = True, backfill_days: int = 0) -> None:
+def poll_once(cfg: dict, session: requests.Session, verbose: bool = True, backfill_days: int = 0, no_html: bool = False) -> None:
     stations = fetch_level_stations(session, cfg["lat"], cfg["lon"], cfg["radius_km"])
     conn = init_db(Path(cfg["db"]))
     if backfill_days:
@@ -447,13 +447,15 @@ def poll_once(cfg: dict, session: requests.Session, verbose: bool = True, backfi
     else:
         readings = extract_readings(stations)
     new_rows = store_readings(conn, readings)
-    build_dashboard(conn, Path(cfg["output"]))
+    if not no_html:
+        build_dashboard(conn, Path(cfg["output"]))
     conn.close()
     if verbose:
         ts = datetime.now().strftime("%Y-%m-%d %H:%M:%S")
+        suffix = "" if no_html else f" -> {cfg['output']}"
         print(
             f"[{ts}] {len(readings)} readings from {len(stations)} stations "
-            f"({new_rows} new) -> {cfg['output']}"
+            f"({new_rows} new){suffix}"
         )
 
 
@@ -470,6 +472,7 @@ def main() -> None:
     parser.add_argument("--interval", type=int, default=900, help="Seconds between polls in --daemon mode (default: 900)")
     parser.add_argument("--backfill", action="store_true", help="Fetch full history (up to --backfill-days) for all stations, then exit")
     parser.add_argument("--backfill-days", type=int, default=28, dest="backfill_days", help="How many days of history to backfill (default: 28, max: 28)")
+    parser.add_argument("--no-html", action="store_true", dest="no_html", help="Skip HTML dashboard generation (use when a web page reads the DB directly)")
     args = parser.parse_args()
 
     session = requests.Session()
@@ -485,7 +488,7 @@ def main() -> None:
 
     if args.backfill:
         try:
-            poll_once(cfg, session, backfill_days=min(args.backfill_days, 28))
+            poll_once(cfg, session, backfill_days=min(args.backfill_days, 28), no_html=args.no_html)
         except requests.RequestException as exc:
             print(f"Backfill failed: {exc}", file=sys.stderr)
             sys.exit(1)
@@ -493,13 +496,13 @@ def main() -> None:
         print(f"Running as daemon, polling every {args.interval}s. Ctrl+C to stop.")
         while True:
             try:
-                poll_once(cfg, session)
+                poll_once(cfg, session, no_html=args.no_html)
             except requests.RequestException as exc:
                 print(f"Poll failed: {exc}", file=sys.stderr)
             time.sleep(args.interval)
     else:
         try:
-            poll_once(cfg, session)
+            poll_once(cfg, session, no_html=args.no_html)
         except requests.RequestException as exc:
             print(f"Poll failed: {exc}", file=sys.stderr)
             sys.exit(1)

synology-task.sh

@@ -0,0 +1,21 @@
+#!/bin/sh
+# River monitor poller — run this via Synology Task Scheduler every 15 minutes.
+#
+# Setup:
+#   1. Copy river_monitor.py to your Synology (e.g. /volume1/homes/simon/river_monitor.py)
+#   2. Set WEB_DATA_DIR below to the data/ folder inside your web repo on the Synology
+#   3. In DSM: Control Panel → Task Scheduler → Create → Scheduled Task → User-defined script
+#      - User: your DSM user (needs write access to WEB_DATA_DIR)
+#      - Schedule: every 15 minutes
+#      - Task: sh /volume1/homes/simon/synology-task.sh
+#   4. Run once manually with --backfill to populate history, then let the schedule take over
+
+SCRIPT=/volume1/homes/simon/river_monitor.py
+WEB_DATA_DIR=/volume1/web/data
+DB=$WEB_DATA_DIR/river_levels.db
+LOG=$WEB_DATA_DIR/river-monitor.log
+
+/usr/bin/python3 "$SCRIPT" \
+    --db "$DB" \
+    --no-html \
+    >> "$LOG" 2>&1