Initial commit: Sentry-Emote system monitor

- Aggregator: Flask-based event broker with priority queue
- Frontend: OLED-optimized UI with animations
- Detectors: disk, cpu, memory, service, network
- Unified entry point (sentry.py) with process management
- Heartbeat TTL system for auto-clearing stale events

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

detectors/service.py

@@ -0,0 +1,108 @@
+"""
+Service Health Detector
+Monitors if specific processes/services are running.
+
+Environment variables:
+    AGGREGATOR_URL  - URL of the aggregator (default: http://localhost:5000)
+    CHECK_INTERVAL  - Seconds between checks (default: 30)
+    SERVICES        - Comma-separated list of process names to monitor (required)
+                      Example: "nginx,postgres,redis"
+"""
+
+import os
+import sys
+import time
+import psutil
+import requests
+
+# Configuration from environment
+AGGREGATOR_URL = os.environ.get("AGGREGATOR_URL", "http://localhost:5000")
+CHECK_INTERVAL = int(os.environ.get("CHECK_INTERVAL", 30))
+SERVICES = os.environ.get("SERVICES", "")
+
+
+def get_running_processes():
+    """Get set of running process names."""
+    running = set()
+    for proc in psutil.process_iter(['name']):
+        try:
+            name = proc.info['name']
+            if name:
+                # Store both with and without common extensions
+                running.add(name.lower())
+                if name.lower().endswith('.exe'):
+                    running.add(name.lower()[:-4])
+        except (psutil.NoSuchProcess, psutil.AccessDenied):
+            pass
+    return running
+
+
+def send_event(event_id, priority, message):
+    """Send an event to the aggregator with heartbeat TTL."""
+    ttl = CHECK_INTERVAL * 2
+    try:
+        response = requests.post(
+            f"{AGGREGATOR_URL}/event",
+            json={"id": event_id, "priority": priority, "message": message, "ttl": ttl},
+            timeout=5
+        )
+        print(f"[EVENT] {event_id}: {message} (priority {priority}, ttl {ttl}s) -> {response.status_code}")
+    except requests.RequestException as e:
+        print(f"[ERROR] Failed to send event: {e}")
+
+
+def clear_event(event_id):
+    """Clear the event from the aggregator."""
+    try:
+        response = requests.post(
+            f"{AGGREGATOR_URL}/clear",
+            json={"id": event_id},
+            timeout=5
+        )
+        if response.status_code == 200:
+            print(f"[CLEAR] {event_id}")
+    except requests.RequestException as e:
+        print(f"[ERROR] Failed to clear event: {e}")
+
+
+def main():
+    if not SERVICES:
+        print("ERROR: SERVICES environment variable is required")
+        print("Example: SERVICES=nginx,postgres,redis python detectors/service.py")
+        sys.exit(1)
+
+    services = [s.strip().lower() for s in SERVICES.split(",") if s.strip()]
+
+    print(f"Service Health Detector started")
+    print(f"  Aggregator: {AGGREGATOR_URL}")
+    print(f"  Interval: {CHECK_INTERVAL}s")
+    print(f"  Monitoring: {', '.join(services)}")
+    print()
+
+    # Track which services have active alerts
+    active_alerts = set()
+
+    while True:
+        running = get_running_processes()
+        current_alerts = set()
+
+        for service in services:
+            event_id = f"service_{service}"
+
+            if service not in running:
+                send_event(event_id, 1, f"Service '{service}' is not running")
+                current_alerts.add(event_id)
+            else:
+                print(f"[OK] Service '{service}' is running")
+
+        # Clear alerts for services that are now running
+        for event_id in active_alerts - current_alerts:
+            clear_event(event_id)
+
+        active_alerts = current_alerts
+
+        time.sleep(CHECK_INTERVAL)
+
+
+if __name__ == "__main__":
+    main()