Add healthcheck

.env.example

@@ -9,3 +9,7 @@ MYSQL_ROOT_PASSWORD=root_password
 COLLECT_INTERVAL_SECONDS=900
 APP_TIMEZONE=Europe/London
 FLASK_SECRET_KEY=replace-with-a-random-string
+
+# Optional: healthcheck.io-style heartbeat URL
+# On success: GET <url>  |  On failure: POST <url>/fail
+HEALTHCHECK_URL=https://health.pattinson.org/ping/2009942a-9877-411e-89b4-3d17382c8286

app/collector.py

@@ -2,6 +2,8 @@ from __future__ import annotations
 
 import logging
 import time
+import urllib.error
+import urllib.request
 from datetime import datetime, timezone
 from typing import Any
 
@@ -73,6 +75,27 @@ def save_reading(device: Device, status: dict[str, Any]) -> None:
     )
 
 
+def _ping_healthcheck(success: bool, detail: str | None = None) -> None:
+    url = config.healthcheck_url
+    if not url:
+        logger.debug("Healthcheck ping skipped: HEALTHCHECK_URL not configured")
+        return
+    try:
+        if success:
+            logger.debug("Pinging healthcheck (success): %s", url)
+            urllib.request.urlopen(url, timeout=10)  # noqa: S310
+            logger.info("Healthcheck ping sent successfully")
+        else:
+            fail_url = f"{url}/fail"
+            logger.debug("Pinging healthcheck (fail): %s — %s", fail_url, detail)
+            payload = (detail or "").encode()
+            req = urllib.request.Request(fail_url, data=payload, method="POST")
+            urllib.request.urlopen(req, timeout=10)  # noqa: S310
+            logger.info("Healthcheck fail ping sent: %s", detail)
+    except Exception as exc:  # noqa: BLE001
+        logger.warning("Healthcheck ping failed: %s", exc)
+
+
 def collect_once(client: SwitchBotClient) -> None:
     logger.info("Starting collection cycle")
     devices = sync_devices(client)
@@ -106,8 +129,10 @@ def main() -> int:
         started = time.monotonic()
         try:
             collect_once(client)
-        except Exception:
+            _ping_healthcheck(True)
+        except Exception as exc:
             logger.exception("Collector cycle failed")
+            _ping_healthcheck(False, str(exc))
         elapsed = time.monotonic() - started
         time.sleep(max(1, interval - elapsed))
 

app/config.py

@@ -20,6 +20,7 @@ class Config:
     collect_interval_seconds: int = int(os.getenv("COLLECT_INTERVAL_SECONDS", "900"))
     app_timezone: str = os.getenv("APP_TIMEZONE", "Europe/London")
     flask_secret_key: str = os.getenv("FLASK_SECRET_KEY", "dev-only-secret")
+    healthcheck_url: str | None = os.getenv("HEALTHCHECK_URL")
 
 
 config = Config()

app/templates/dashboard.html

@@ -6,8 +6,7 @@
   <section class="hero">
     <div>
       <p class="eyebrow">Today so far</p>
-      <h1>Temperature dashboard</h1>
+      <h1>Vet Temperatures</h1>
-      <p class="muted">Local timezone: {{ timezone }}. Collector interval: {{ collect_interval_seconds // 60 }} min.</p>
     </div>
     <a class="button" href="/reports">Make report</a>
   </section>

docker-compose.yml

@@ -40,6 +40,7 @@ services:
       SWITCHBOT_SECRET: ${SWITCHBOT_SECRET:-}
       COLLECT_INTERVAL_SECONDS: ${COLLECT_INTERVAL_SECONDS:-900}
       APP_TIMEZONE: ${APP_TIMEZONE:-Europe/London}
+      HEALTHCHECK_URL: ${HEALTHCHECK_URL:-}
     depends_on:
       db:
         condition: service_healthy