CloudSnooze Event-Driven Plugin Framework Roadmap

This document outlines the implementation plan for the CloudSnooze Event-Driven Plugin Framework, which enables plugins to respond to external events such as AWS Spot instance interruption notifications.

Overview

The Event-Driven Plugin Framework extends CloudSnooze beyond passive monitoring to active event handling. This allows CloudSnooze to trigger appropriate actions when cloud providers or system events require rapid response.

Implementation Phases

Phase 1: Core Event Framework (Q3 2025)

Event System Architecture
- Design event types, priorities, and data structures
- Implement event subscription and dispatch mechanisms
- Create event queue and processing pipeline
Event Source Integration
- AWS EC2 metadata service monitoring for Spot interrupts
- System event sources (disk, memory, network)
- Basic event simulation for testing
Plugin Interface Extensions
- Extend plugin interface for event handling
- Implement event handler registration and discovery
- Develop event handler prioritization system
Testing Framework
- Create event simulation tools for testing
- Implement event processing unit tests
- Develop plugin event handling verification system

Phase 2: AWS Spot Instance Handler (Q4 2025)

Spot Interrupt Detection
- EC2 instance metadata service monitoring
- Instance termination notice parsing
- Time-to-termination calculation
Graceful Shutdown Framework
- Application notification system
- Configurable shutdown sequence
- Shutdown verification and reporting
Official Plugins
- Database flushing plugins (MySQL, PostgreSQL, Redis)
- Application checkpoint plugins (common frameworks)
- VM state saving plugins
Documentation and Examples
- Comprehensive developer guide
- Plugin implementation examples
- Best practices for shutdown scripting

Phase 3: Additional Cloud Providers (Q1 2026)

Azure Integration
- Azure Scheduled Events API monitoring
- VM termination event handling
- Azure-specific plugins
GCP Integration
- Preemptible VM monitoring
- GCE instance termination events
- GCP-specific plugins
Cross-Provider Abstraction
- Unified event model across providers
- Provider-agnostic plugin development
- Event translation and normalization

Phase 4: Advanced Features (Q2-Q3 2026)

Event Analytics
- Historical event tracking
- Pattern recognition for preemptions
- Predictive event analysis
Multi-Instance Coordination
- Event propagation across instances
- Coordinated shutdown for distributed systems
- Leader election for orchestrated shutdowns
Cost Optimization Strategies
- Automated bidding strategies for Spot instances
- Instance type recommendations based on interruption patterns
- Workload scheduling around interruption patterns

Specific Implementation Milestones

AWS Spot Instance Handler

Metadata Service Monitoring
- Poll EC2 metadata service at /latest/meta-data/spot/instance-action
- Parse JSON response for action and time
- Calculate remaining time before termination

Plugin Execution Flow

1. CloudSnooze Daemon detects Spot termination notice
2. Event Manager creates Spot interrupt event
3. Plugin Manager finds plugins registered for this event
4. Plugins execute in priority order:
   a. High priority: Critical data saving
   b. Medium priority: Application state checkpointing
   c. Low priority: Notification and logging
5. Results are collected and logged
6. Instance prepares for termination

Configuration Example

{
  "event_handlers": {
    "cloud.spot.interrupt": {
      "enabled": true,
      "polling_interval_seconds": 5,
      "plugins": [
        {
          "name": "mysql-flusher",
          "priority": 100,
          "timeout_seconds": 30,
          "config": {
            "connection_string": "user:pass@tcp(localhost:3306)/db"
          }
        },
        {
          "name": "app-checkpointer",
          "priority": 80,
          "timeout_seconds": 45,
          "config": {
            "app_endpoint": "http://localhost:8080/checkpoint",
            "verify_success": true
          }
        },
        {
          "name": "slack-notifier",
          "priority": 10,
          "config": {
            "webhook_url": "https://hooks.slack.com/services/...",
            "channel": "#cloud-events"
          }
        }
      ]
    }
  }
}

Implementing Cloud Event Sources

For AWS Spot instances, the implementation will:

Create a background goroutine that periodically polls:

func pollSpotInterruptNotices(ctx context.Context, eventCh chan<- Event) {
    ticker := time.NewTicker(5 * time.Second)
    defer ticker.Stop()

    for {
        select {
        case <-ctx.Done():
            return
        case <-ticker.C:
            resp, err := http.Get("http://169.254.169.254/latest/meta-data/spot/instance-action")
            if err != nil || resp.StatusCode != 200 {
                // No notice yet
                continue
            }

            defer resp.Body.Close()
            var notice SpotInterruptNotice
            if err := json.NewDecoder(resp.Body).Decode(&notice); err != nil {
                log.Printf("Error decoding spot interrupt notice: %v", err)
                continue
            }

            // Create and dispatch event
            event := Event{
                Type:      EventSpotInterrupt,
                Source:    "aws.ec2.metadata-service",
                Timestamp: time.Now(),
                ID:        uuid.New().String(),
                Severity:  SeverityUrgent,
                Data: map[string]interface{}{
                    "action":         notice.Action,
                    "time":           notice.Time,
                    "timeRemaining":  time.Until(notice.Time).Seconds(),
                    "instanceID":     getInstanceID(),
                    "instanceType":   getInstanceType(),
                },
            }

            eventCh <- event
        }
    }
}

func (em *EventManager) Start(ctx context.Context) error {
    em.eventCh = make(chan Event, 100)

    // Start event processing goroutine
    go em.processEvents(ctx)

    // Start event sources
    if em.config.AWS.SpotInterruptMonitoring.Enabled {
        go pollSpotInterruptNotices(ctx, em.eventCh)
    }

    // Add other event sources...

    return nil
}

Third-Party Integration Examples

1. Database Flushing on Spot Termination

// Example plugin for MySQL database flushing
func (p *MySQLFlusher) HandleEvent(event plugin.Event) (bool, map[string]interface{}, error) {
    if event.Type != plugin.EventSpotInterrupt {
        return false, nil, nil
    }
    
    // Connect to database
    db, err := sql.Open("mysql", p.connectionString)
    if err != nil {
        return false, nil, fmt.Errorf("failed to connect to MySQL: %w", err)
    }
    defer db.Close()
    
    // Flush tables with read lock
    _, err = db.Exec("FLUSH TABLES WITH READ LOCK")
    if err != nil {
        return false, nil, fmt.Errorf("failed to flush tables: %w", err)
    }
    
    // Unlock tables after a brief pause to ensure flush completed
    defer func() {
        _, _ = db.Exec("UNLOCK TABLES")
    }()
    
    return true, map[string]interface{}{
        "status": "mysql_flushed",
        "tables_flushed": true,
    }, nil
}

2. Application Checkpoint Trigger

# Example external plugin for application checkpoint
class AppCheckpointer:
    def __init__(self):
        self.app_endpoint = "http://localhost:8080/api/checkpoint"
        self.timeout_seconds = 30
        
    def handle_event(self, event):
        if event.get("type") != "cloud.spot.interrupt":
            return {"handled": False}
            
        try:
            # Call application checkpoint API
            response = requests.post(
                self.app_endpoint,
                json={
                    "reason": "spot_termination",
                    "time_remaining": event["data"]["timeRemaining"]
                },
                timeout=self.timeout_seconds
            )
            
            if response.status_code == 200:
                return {
                    "handled": True,
                    "status": "checkpoint_triggered",
                    "app_response": response.json()
                }
            else:
                return {
                    "handled": False,
                    "error": f"Checkpoint API returned status {response.status_code}"
                }
                
        except Exception as e:
            return {
                "handled": False,
                "error": str(e)
            }

Success Metrics and Goals

Reliability Metrics
- 99.9% successful handling of Spot termination events
- <5 second detection-to-action latency
- <1% plugin execution failures
Community Engagement
- 10+ event handler plugins available at launch
- 5+ third-party plugins within 3 months
- Developer documentation with >90% satisfaction
Business Impact
- 30%+ cost savings through safe Spot instance usage
- <1% data loss incidents on Spot terminations
- 50%+ reduction in manual intervention for spot terminations