466 lines
17 KiB
Python
466 lines
17 KiB
Python
"""
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Health Check System
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Provides comprehensive health monitoring for all system components including
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database connectivity, WebSocket connections, external services, and application state.
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Features:
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- Deep health checks for all dependencies
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- Readiness and liveness probes
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- Graceful degradation strategies
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- Health status aggregation
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- Kubernetes-compatible endpoints
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"""
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import asyncio
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import time
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from datetime import datetime, timedelta
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from typing import Dict, Any, List, Optional, NamedTuple
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from enum import Enum
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from logger import logger
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class HealthStatus(Enum):
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"""Health status levels."""
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HEALTHY = "healthy"
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DEGRADED = "degraded"
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UNHEALTHY = "unhealthy"
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UNKNOWN = "unknown"
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class HealthCheckResult(NamedTuple):
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"""Result of a health check."""
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component: str
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status: HealthStatus
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message: str
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duration_ms: float
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details: Dict[str, Any]
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timestamp: datetime
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class HealthCheckComponent:
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"""Base class for health check components."""
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def __init__(self, name: str, timeout_seconds: float = 5.0):
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self.name = name
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self.timeout_seconds = timeout_seconds
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self.last_check: Optional[HealthCheckResult] = None
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self.check_count = 0
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self.failure_count = 0
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async def check_health(self) -> HealthCheckResult:
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"""Perform health check with timeout."""
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start_time = time.time()
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self.check_count += 1
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try:
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# Run the actual health check with timeout
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result = await asyncio.wait_for(
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self._perform_check(),
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timeout=self.timeout_seconds
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)
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duration_ms = (time.time() - start_time) * 1000
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self.last_check = HealthCheckResult(
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component=self.name,
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status=result.get('status', HealthStatus.UNKNOWN),
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message=result.get('message', ''),
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duration_ms=duration_ms,
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details=result.get('details', {}),
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timestamp=datetime.now()
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)
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if self.last_check.status != HealthStatus.HEALTHY:
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self.failure_count += 1
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return self.last_check
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except asyncio.TimeoutError:
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self.failure_count += 1
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duration_ms = (time.time() - start_time) * 1000
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self.last_check = HealthCheckResult(
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component=self.name,
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status=HealthStatus.UNHEALTHY,
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message=f"Health check timeout after {self.timeout_seconds}s",
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duration_ms=duration_ms,
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details={"error": "timeout"},
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timestamp=datetime.now()
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)
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return self.last_check
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except Exception as e:
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self.failure_count += 1
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duration_ms = (time.time() - start_time) * 1000
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self.last_check = HealthCheckResult(
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component=self.name,
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status=HealthStatus.UNHEALTHY,
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message=f"Health check failed: {str(e)}",
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duration_ms=duration_ms,
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details={"error": str(e), "error_type": type(e).__name__},
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timestamp=datetime.now()
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)
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return self.last_check
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async def _perform_check(self) -> Dict[str, Any]:
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"""Override this method to implement specific health check logic."""
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raise NotImplementedError("Subclasses must implement _perform_check")
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def get_failure_rate(self) -> float:
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"""Get failure rate as percentage."""
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if self.check_count == 0:
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return 0.0
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return (self.failure_count / self.check_count) * 100
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class DatabaseHealthCheck(HealthCheckComponent):
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"""Health check for database connectivity."""
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def __init__(self, session_manager, timeout_seconds: float = 3.0):
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super().__init__("database", timeout_seconds)
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self.session_manager = session_manager
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async def _perform_check(self) -> Dict[str, Any]:
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"""Check database connectivity and basic operations."""
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try:
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# Test basic session operations
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session_count = len(self.session_manager.sessions)
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# Test session file read/write
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test_session_id = "health_check_test"
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if test_session_id in self.session_manager.sessions:
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del self.session_manager.sessions[test_session_id]
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return {
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'status': HealthStatus.HEALTHY,
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'message': f"Database operational, {session_count} sessions",
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'details': {
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'session_count': session_count,
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'test_completed': True
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}
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}
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except Exception as e:
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return {
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'status': HealthStatus.UNHEALTHY,
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'message': f"Database check failed: {str(e)}",
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'details': {'error': str(e)}
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}
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class WebSocketHealthCheck(HealthCheckComponent):
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"""Health check for WebSocket connections."""
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def __init__(self, session_manager, timeout_seconds: float = 2.0):
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super().__init__("websocket", timeout_seconds)
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self.session_manager = session_manager
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async def _perform_check(self) -> Dict[str, Any]:
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"""Check WebSocket connection health."""
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try:
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# Count active WebSocket connections
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active_connections = 0
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total_sessions = len(self.session_manager.sessions)
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for session in self.session_manager.sessions.values():
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if hasattr(session, 'websocket') and session.websocket:
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active_connections += 1
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# Determine health based on connection ratio
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if total_sessions > 0:
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connection_ratio = active_connections / total_sessions
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if connection_ratio > 0.8:
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status = HealthStatus.HEALTHY
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message = f"WebSocket connections healthy ({active_connections}/{total_sessions})"
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elif connection_ratio > 0.5:
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status = HealthStatus.DEGRADED
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message = f"Some WebSocket connections lost ({active_connections}/{total_sessions})"
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else:
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status = HealthStatus.UNHEALTHY
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message = f"Many WebSocket connections lost ({active_connections}/{total_sessions})"
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else:
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status = HealthStatus.HEALTHY
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message = "No active sessions"
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return {
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'status': status,
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'message': message,
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'details': {
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'active_connections': active_connections,
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'total_sessions': total_sessions,
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'connection_ratio': active_connections / max(total_sessions, 1)
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}
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}
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except Exception as e:
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return {
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'status': HealthStatus.UNHEALTHY,
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'message': f"WebSocket check failed: {str(e)}",
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'details': {'error': str(e)}
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}
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class LobbyHealthCheck(HealthCheckComponent):
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"""Health check for lobby management."""
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def __init__(self, lobby_manager, timeout_seconds: float = 2.0):
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super().__init__("lobby", timeout_seconds)
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self.lobby_manager = lobby_manager
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async def _perform_check(self) -> Dict[str, Any]:
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"""Check lobby management health."""
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try:
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lobby_count = len(self.lobby_manager.lobbies)
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active_lobbies = sum(1 for lobby in self.lobby_manager.lobbies.values()
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if len(lobby.sessions) > 0)
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return {
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'status': HealthStatus.HEALTHY,
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'message': f"Lobby system operational, {active_lobbies}/{lobby_count} active",
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'details': {
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'total_lobbies': lobby_count,
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'active_lobbies': active_lobbies,
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'empty_lobbies': lobby_count - active_lobbies
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}
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}
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except Exception as e:
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return {
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'status': HealthStatus.UNHEALTHY,
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'message': f"Lobby check failed: {str(e)}",
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'details': {'error': str(e)}
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}
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class SystemResourceHealthCheck(HealthCheckComponent):
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"""Health check for system resources."""
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def __init__(self, metrics_collector, timeout_seconds: float = 1.0):
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super().__init__("system_resources", timeout_seconds)
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self.metrics_collector = metrics_collector
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async def _perform_check(self) -> Dict[str, Any]:
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"""Check system resource utilization."""
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try:
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current_metrics = self.metrics_collector.get_current_metrics()
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cpu_usage = current_metrics['gauges'].get('cpu_usage_percent', 0)
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memory_usage = current_metrics['gauges'].get('memory_usage_percent', 0)
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# Determine status based on resource usage
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if cpu_usage > 90 or memory_usage > 90:
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status = HealthStatus.UNHEALTHY
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message = f"High resource usage: CPU {cpu_usage:.1f}%, Memory {memory_usage:.1f}%"
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elif cpu_usage > 70 or memory_usage > 70:
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status = HealthStatus.DEGRADED
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message = f"Moderate resource usage: CPU {cpu_usage:.1f}%, Memory {memory_usage:.1f}%"
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else:
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status = HealthStatus.HEALTHY
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message = f"Resource usage normal: CPU {cpu_usage:.1f}%, Memory {memory_usage:.1f}%"
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return {
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'status': status,
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'message': message,
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'details': {
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'cpu_usage_percent': cpu_usage,
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'memory_usage_percent': memory_usage,
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'memory_usage_mb': current_metrics['gauges'].get('memory_usage_mb', 0)
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}
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}
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except Exception as e:
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return {
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'status': HealthStatus.UNHEALTHY,
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'message': f"System resource check failed: {str(e)}",
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'details': {'error': str(e)}
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}
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class HealthMonitor:
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"""Main health monitoring system."""
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def __init__(self):
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self.components: Dict[str, HealthCheckComponent] = {}
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self.check_interval_seconds = 30.0
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self.last_full_check: Optional[datetime] = None
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self._monitoring_task: Optional[asyncio.Task] = None
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self._running = False
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# Health history for trends
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self.health_history: List[Dict[str, Any]] = []
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self.max_history_entries = 100
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def register_component(self, component: HealthCheckComponent):
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"""Register a health check component."""
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self.components[component.name] = component
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logger.info(f"Registered health check component: {component.name}")
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async def check_all_components(self) -> Dict[str, HealthCheckResult]:
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"""Check health of all registered components."""
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results = {}
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# Run all health checks in parallel
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tasks = {
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name: component.check_health()
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for name, component in self.components.items()
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}
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completed_results = await asyncio.gather(*tasks.values(), return_exceptions=True)
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for name, result in zip(tasks.keys(), completed_results):
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if isinstance(result, Exception):
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# Handle exceptions in health checks
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results[name] = HealthCheckResult(
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component=name,
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status=HealthStatus.UNHEALTHY,
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message=f"Health check exception: {str(result)}",
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duration_ms=0.0,
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details={"error": str(result)},
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timestamp=datetime.now()
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)
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else:
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results[name] = result
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self.last_full_check = datetime.now()
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# Store in history
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self._store_health_history(results)
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return results
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def _store_health_history(self, results: Dict[str, HealthCheckResult]):
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"""Store health check results in history."""
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history_entry = {
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'timestamp': datetime.now().isoformat(),
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'overall_status': self._calculate_overall_status(results).value,
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'components': {
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name: {
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'status': result.status.value,
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'duration_ms': result.duration_ms,
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'message': result.message
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}
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for name, result in results.items()
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}
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}
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self.health_history.append(history_entry)
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# Keep history size manageable
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if len(self.health_history) > self.max_history_entries:
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self.health_history = self.health_history[-self.max_history_entries:]
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def _calculate_overall_status(self, results: Dict[str, HealthCheckResult]) -> HealthStatus:
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"""Calculate overall system health status."""
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if not results:
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return HealthStatus.UNKNOWN
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statuses = [result.status for result in results.values()]
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if HealthStatus.UNHEALTHY in statuses:
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return HealthStatus.UNHEALTHY
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elif HealthStatus.DEGRADED in statuses:
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return HealthStatus.DEGRADED
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elif all(status == HealthStatus.HEALTHY for status in statuses):
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return HealthStatus.HEALTHY
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else:
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return HealthStatus.UNKNOWN
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async def get_health_summary(self) -> Dict[str, Any]:
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"""Get comprehensive health summary."""
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results = await self.check_all_components()
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overall_status = self._calculate_overall_status(results)
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return {
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'status': overall_status.value,
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'timestamp': datetime.now().isoformat(),
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'components': {
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name: {
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'status': result.status.value,
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'message': result.message,
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'duration_ms': result.duration_ms,
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'details': result.details,
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'failure_rate': self.components[name].get_failure_rate()
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}
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for name, result in results.items()
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},
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'last_check': self.last_full_check.isoformat() if self.last_full_check else None,
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'check_interval_seconds': self.check_interval_seconds
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}
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async def start_monitoring(self):
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"""Start continuous health monitoring."""
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if self._running:
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return
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self._running = True
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self._monitoring_task = asyncio.create_task(self._monitoring_loop())
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logger.info("Health monitoring started")
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async def stop_monitoring(self):
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"""Stop health monitoring."""
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self._running = False
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if self._monitoring_task:
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self._monitoring_task.cancel()
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try:
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await self._monitoring_task
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except asyncio.CancelledError:
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pass
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logger.info("Health monitoring stopped")
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async def _monitoring_loop(self):
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"""Main health monitoring loop."""
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while self._running:
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try:
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await self.check_all_components()
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await asyncio.sleep(self.check_interval_seconds)
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except asyncio.CancelledError:
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break
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except Exception as e:
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logger.error(f"Error in health monitoring loop: {e}")
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await asyncio.sleep(5.0) # Back off on error
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def get_readiness_status(self) -> Dict[str, Any]:
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"""Get readiness probe status (for Kubernetes)."""
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if not self.last_full_check:
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return {
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'ready': False,
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'reason': 'No health checks completed yet'
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}
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# Check if recent health check was successful
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time_since_check = datetime.now() - self.last_full_check
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if time_since_check > timedelta(minutes=2):
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return {
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'ready': False,
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'reason': 'Health checks stale'
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}
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# Get latest results
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critical_components = ['database', 'websocket']
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for component_name in critical_components:
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component = self.components.get(component_name)
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if component and component.last_check:
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if component.last_check.status == HealthStatus.UNHEALTHY:
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return {
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'ready': False,
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'reason': f'Critical component {component_name} unhealthy'
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}
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return {'ready': True}
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def get_liveness_status(self) -> Dict[str, Any]:
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"""Get liveness probe status (for Kubernetes)."""
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# Simple liveness check - ensure monitoring is running
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return {
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'alive': self._running or self.last_full_check is not None,
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'last_check': self.last_full_check.isoformat() if self.last_full_check else None
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}
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# Global health monitor instance
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health_monitor = HealthMonitor()
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