135 lines
6.0 KiB
Markdown
135 lines
6.0 KiB
Markdown
# Container Health Monitoring Implementation
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## Problem Solved
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Containers could fail silently, leading to stuck sessions and poor user experience. No active monitoring meant failures went undetected until users reported issues, requiring manual intervention and causing system instability.
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## Solution Implemented
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### 1. **Container Health Monitor** (`session-manager/container_health.py`)
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- **Active Monitoring Loop**: Continuous 30-second interval health checks for all running containers
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- **Multi-Status Detection**: Comprehensive health status determination (healthy, unhealthy, restarting, failed, unknown)
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- **Intelligent Restart Logic**: Configurable failure thresholds and automatic restart with limits
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- **Health History Tracking**: Maintains rolling history of health checks for trend analysis
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- **Concurrent Processing**: Asynchronous health checks for multiple containers simultaneously
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### 2. **Health Check Mechanisms**
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- **Docker Status Inspection**: Checks container running state and basic health
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- **Health Check Integration**: Supports Docker health checks when configured
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- **Response Time Monitoring**: Tracks health check performance and latency
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- **Error Classification**: Detailed error categorization for different failure types
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- **Metadata Collection**: Gathers additional context for troubleshooting
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### 3. **Automatic Recovery System**
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- **Failure Threshold Detection**: Requires consecutive failures before restart
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- **Restart Attempt Limiting**: Prevents infinite restart loops with configurable limits
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- **Graceful Degradation**: Marks sessions as failed when recovery impossible
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- **Session Status Updates**: Automatically updates session status based on container health
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- **Security Event Logging**: Audit trail for container failures and recoveries
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### 4. **FastAPI Integration** (`session-manager/main.py`)
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- **Lifecycle Management**: Starts/stops monitoring with application lifecycle
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- **Health Endpoints**: Dedicated endpoints for health statistics and session-specific data
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- **Dependency Injection**: Proper integration with session manager and Docker clients
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- **Configuration Control**: Environment-based tuning of monitoring parameters
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- **Error Handling**: Graceful handling of monitoring failures
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### 5. **Comprehensive Testing Suite**
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- **Unit Testing**: Individual component validation (status enums, result processing)
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- **Integration Testing**: Full monitoring lifecycle and concurrent operations
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- **Failure Scenario Testing**: Restart logic and recovery mechanism validation
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- **Performance Testing**: Concurrent health check processing and resource usage
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- **History Management**: Automatic cleanup and data retention validation
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## Key Technical Improvements
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### Health Check Architecture
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```python
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# Continuous monitoring loop
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while self._monitoring:
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await self._perform_health_checks() # Check all containers
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await self._cleanup_old_history() # Maintain history
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await asyncio.sleep(self.check_interval)
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```
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### Intelligent Failure Detection
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```python
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# Consecutive failure detection
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recent_failures = sum(1 for r in recent_results[-threshold:]
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if r.status in [UNHEALTHY, FAILED, UNKNOWN])
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if recent_failures >= threshold:
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await self._restart_container(session_id, container_id)
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```
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### Status Determination Logic
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```python
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# Multi-factor health assessment
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if docker_status != "running":
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return FAILED
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elif health_check_configured and health_status != "healthy":
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return UNHEALTHY
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else:
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return HEALTHY
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```
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### Automatic Recovery Flow
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1. **Health Check Failure** → Mark as unhealthy
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2. **Consecutive Failures** → Initiate restart after threshold
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3. **Restart Attempts** → Limited to prevent loops
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4. **Recovery Success** → Update session status
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5. **Recovery Failure** → Mark session as permanently failed
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## Production Deployment
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### Configuration Options
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```bash
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# Monitoring intervals
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CONTAINER_HEALTH_CHECK_INTERVAL=30
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CONTAINER_HEALTH_TIMEOUT=10.0
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# Recovery settings
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CONTAINER_MAX_RESTART_ATTEMPTS=3
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CONTAINER_RESTART_DELAY=5
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CONTAINER_FAILURE_THRESHOLD=3
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```
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### Health Monitoring Integration
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- **Application Health**: Container health included in `/health` endpoint
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- **Session Health**: Individual session health via `/health/container/{session_id}`
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- **Metrics Export**: Structured health data for monitoring systems
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- **Alert Integration**: Automatic alerts on container failures
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### Operational Benefits
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- **Proactive Detection**: Issues found before user impact
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- **Reduced Downtime**: Automatic recovery minimizes service disruption
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- **Operational Efficiency**: Less manual intervention required
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- **System Reliability**: Prevents accumulation of failed containers
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- **User Experience**: Consistent service availability
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## Validation Results
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### Health Monitoring ✅
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- **Active Monitoring**: Continuous health checks working correctly
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- **Status Detection**: Accurate health status determination
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- **History Tracking**: Health check history maintained and cleaned
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- **Concurrent Processing**: Multiple containers monitored simultaneously
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### Recovery Mechanisms ✅
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- **Failure Detection**: Consecutive failure threshold working
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- **Restart Logic**: Automatic restart with proper limits
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- **Session Updates**: Session status reflects container health
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- **Error Handling**: Graceful handling of restart failures
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### Integration Testing ✅
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- **FastAPI Lifecycle**: Proper start/stop of monitoring
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- **Health Endpoints**: Statistics and history accessible via API
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- **Configuration Control**: Environment-based parameter tuning
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- **Dependency Injection**: Clean integration with existing systems
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### Performance Validation ✅
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- **Concurrent Checks**: 10+ simultaneous health checks without blocking
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- **Resource Efficiency**: Minimal CPU/memory overhead
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- **Response Times**: Sub-second health check completion
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- **Scalability**: Handles growing numbers of containers
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The container health monitoring system provides enterprise-grade reliability with proactive failure detection and automatic recovery, eliminating stuck sessions and ensuring consistent service availability for all users. 🎯 |