Updated network

app_example.py

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+#!/usr/bin/env python3
+"""
+Example Flask application with proper health endpoint for Nomad/Consul.
+
+This template shows:
+- Health check endpoint (CRITICAL for Nomad!)
+- Graceful shutdown handling
+- Environment variable configuration
+- Logging setup
+- Error handling
+"""
+
+import os
+import sys
+import logging
+import signal
+from datetime import datetime
+from flask import Flask, jsonify, request
+
+# Configure logging
+logging.basicConfig(
+    level=logging.INFO,
+    format='%(asctime)s - %(name)s - %(levelname)s - %(message)s',
+    handlers=[
+        logging.StreamHandler(sys.stdout)
+    ]
+)
+logger = logging.getLogger(__name__)
+
+# Create Flask app
+app = Flask(__name__)
+
+# Configuration from environment
+PORT = int(os.getenv('PORT', 5000))
+APP_ENV = os.getenv('APP_ENV', 'development')
+
+# Global state for graceful shutdown
+is_shutting_down = False
+
+
+@app.route('/')
+def index():
+    """Main endpoint - replace with your application logic."""
+    return jsonify({
+        'message': 'Hello from Flask!',
+        'environment': APP_ENV,
+        'timestamp': datetime.utcnow().isoformat()
+    })
+
+
+@app.route('/health')
+def health():
+    """
+    Health check endpoint - CRITICAL for Nomad/Consul!
+    
+    This endpoint is called by Consul every 10 seconds.
+    If this returns non-200 status, Consul marks service as unhealthy.
+    
+    Returns:
+        200 OK: Service is healthy
+        503 Service Unavailable: Service is shutting down or unhealthy
+    """
+    if is_shutting_down:
+        logger.warning("Health check called during shutdown")
+        return jsonify({
+            'status': 'shutting_down',
+            'timestamp': datetime.utcnow().isoformat()
+        }), 503
+    
+    # Add your health checks here
+    health_status = {
+        'status': 'healthy',
+        'timestamp': datetime.utcnow().isoformat(),
+        'environment': APP_ENV,
+        'checks': {
+            'app': 'ok',
+            # Add more checks as needed:
+            # 'database': check_database(),
+            # 'cache': check_cache(),
+        }
+    }
+    
+    return jsonify(health_status), 200
+
+
+@app.route('/ready')
+def ready():
+    """
+    Readiness check endpoint (optional).
+    
+    Use this for more complex readiness checks (DB connections, etc.)
+    Nomad can use this as additional check.
+    """
+    return jsonify({
+        'ready': True,
+        'timestamp': datetime.utcnow().isoformat()
+    }), 200
+
+
+@app.route('/metrics')
+def metrics():
+    """
+    Metrics endpoint for monitoring (optional).
+    
+    Can be scraped by Prometheus if you set it up.
+    """
+    # Example basic metrics
+    return jsonify({
+        'requests_total': 0,  # Implement counter
+        'uptime_seconds': 0,  # Implement uptime tracking
+        'timestamp': datetime.utcnow().isoformat()
+    }), 200
+
+
+@app.errorhandler(404)
+def not_found(error):
+    """Handle 404 errors."""
+    return jsonify({'error': 'Not found'}), 404
+
+
+@app.errorhandler(500)
+def internal_error(error):
+    """Handle 500 errors."""
+    logger.error(f"Internal error: {error}")
+    return jsonify({'error': 'Internal server error'}), 500
+
+
+def shutdown_handler(signum, frame):
+    """
+    Handle shutdown signals gracefully.
+    
+    When Nomad stops the job, it sends SIGTERM.
+    This gives the app time to finish current requests.
+    """
+    global is_shutting_down
+    logger.info(f"Received signal {signum}, initiating graceful shutdown...")
+    is_shutting_down = True
+    
+    # Perform cleanup here
+    # - Close database connections
+    # - Finish pending requests
+    # - Save state if needed
+    
+    logger.info("Cleanup complete, exiting...")
+    sys.exit(0)
+
+
+# Register signal handlers
+signal.signal(signal.SIGTERM, shutdown_handler)
+signal.signal(signal.SIGINT, shutdown_handler)
+
+
+if __name__ == '__main__':
+    logger.info(f"Starting Flask app on port {PORT} in {APP_ENV} mode")
+    
+    # Run Flask app
+    app.run(
+        host='0.0.0.0',
+        port=PORT,
+        debug=(APP_ENV == 'development')
+    )