Add health proxy service and Nginx configuration for health checks

backend/health-proxy.py

@@ -0,0 +1,34 @@
+from flask import Flask, request, jsonify, abort
+import requests
+import os
+
+app = Flask(__name__)
+
+# Optional token for access control (not production secure)
+HEALTH_TOKEN = os.environ.get('HEALTH_TOKEN')
+
+@app.route('/healthcheck')
+def healthcheck():
+    token = request.args.get('token') or request.headers.get('X-Health-Token')
+    if HEALTH_TOKEN and token != HEALTH_TOKEN:
+        return jsonify({'error': 'Unauthorized'}), 401
+
+    host = request.args.get('host')
+    port = request.args.get('port')
+    proto = request.args.get('proto', 'http')
+    if not host or not port:
+        return jsonify({'error': 'missing parameters, expected host and port'}), 400
+
+    url = f"{proto}://{host}:{port}"
+
+    try:
+        # Use HEAD to do a lightweight check
+        r = requests.head(url, timeout=4, allow_redirects=True, verify=False)
+        # Any 2xx/3xx is considered OK
+        ok = 200 <= r.status_code < 400
+        return jsonify({'ok': ok, 'status_code': r.status_code}), (200 if ok else 502)
+    except requests.RequestException as e:
+        return jsonify({'ok': False, 'error': str(e)}), 502
+
+if __name__ == '__main__':
+    app.run(host='0.0.0.0', port=8081)