# Agent Lifecycle Management
Caxton provides comprehensive agent lifecycle management capabilities for deploying, managing, and maintaining WebAssembly agents in production environments.
## Overview
The Agent Lifecycle Management system provides:
- **Secure WASM Deployment**: Deploy agents from validated WASM modules
- **State Management**: Type-safe lifecycle transitions with comprehensive tracking
- **Hot Reload**: Zero-downtime updates with multiple deployment strategies
- **Resource Control**: Configurable memory and CPU limits with enforcement
- **Fault Isolation**: Failed agents don't affect other agents in the system
- **Validation Pipeline**: Comprehensive WASM module validation before activation
## Agent Lifecycle States
Agents follow a well-defined state machine:
```
Unloaded → Loaded → Running ⇄ Draining → Stopped
↓
Failed
```
### State Descriptions
- **Unloaded**: Agent is not present in the system
- **Loaded**: WASM module loaded and validated, but not executing
- **Running**: Agent is actively processing messages
- **Draining**: Agent finishing current work before shutdown
- **Stopped**: Agent cleanly shut down, resources released
- **Failed**: Agent encountered an error and was terminated
## Deployment Operations
### Basic Agent Deployment
Deploy an agent from a WASM module:
```rust
use caxton::{AgentLifecycleManager, DeploymentConfig, AgentVersion};
let manager = AgentLifecycleManager::new(/* dependencies */);
// Deploy agent
let result = manager.deploy_agent(
agent_id,
Some(agent_name),
AgentVersion::generate(),
version_number,
DeploymentConfig::immediate(),
wasm_bytes,
).await?;
```
### Deployment Strategies
#### Immediate Deployment
- Replaces agent instantly
- Minimal deployment time
- Brief service interruption
```rust
let config = DeploymentConfig::immediate();
```
#### Rolling Deployment
- Gradual replacement of instances
- Configurable batch size
- Maintains service availability
```rust
let config = DeploymentConfig::rolling(BatchSize::try_new(3)?);
```
#### Blue-Green Deployment
- Deploy to parallel environment
- Switch traffic instantly
- Easy rollback capability
```rust
let config = DeploymentConfig::new(DeploymentStrategy::BlueGreen);
```
#### Canary Deployment
- Deploy to subset of instances
- Gradual traffic increase
- Automatic rollback on issues
```rust
let config = DeploymentConfig::canary();
```
## Hot Reload Operations
### Zero-Downtime Updates
Hot reload enables updating agents without service interruption:
```rust
// Perform hot reload
let result = manager.hot_reload_agent(
agent_id,
Some(agent_name),
new_version,
version_number,
HotReloadConfig::new(HotReloadStrategy::Graceful),
new_wasm_bytes,
).await?;
```
### Hot Reload Strategies
#### Graceful Strategy
- Allows current requests to complete
- Starts new version in parallel
- Switches after warmup period
#### Traffic Splitting Strategy
- Routes percentage of traffic to new version
- Gradually increases traffic split
- Monitors metrics for issues
#### Parallel Strategy
- Runs both versions simultaneously
- Compares responses for validation
- Switches after verification
## Resource Management
### Setting Resource Limits
Configure memory and CPU limits during deployment:
```rust
let config = DeploymentConfig {
strategy: DeploymentStrategy::Immediate,
resource_requirements: ResourceRequirements::new(
DeploymentMemoryLimit::from_mb(10)?, // 10MB limit
DeploymentFuelLimit::try_new(100_000)?, // 100K CPU cycles
),
// ... other config
};
```
### Resource Enforcement
The system enforces limits through:
- **Memory Limits**: WebAssembly linear memory restrictions
- **CPU Limits**: Fuel-based execution metering
- **Execution Time**: Configurable timeouts for operations
- **Message Size**: Limits on incoming/outgoing message sizes
## WASM Module Validation
### Validation Pipeline
All WASM modules undergo comprehensive validation:
1. **Structure Validation**: Valid WASM format and sections
2. **Security Analysis**: Dangerous features detection
3. **Resource Analysis**: Memory and import requirements
4. **Function Validation**: Required exports present
5. **Custom Rules**: User-defined validation criteria
### Security Policies
The validator enforces security policies:
```rust
let policy = WasmSecurityPolicy {
max_memory_pages: 16, // 1MB max memory
max_imports: 10, // Limited imports
allowed_imports: vec![ // Whitelist approach
"env.print".to_string(),
],
deny_unsafe_features: true, // Block SIMD, etc.
};
```
## Monitoring and Observability
### Agent Status Tracking
Monitor agent health and status:
```rust
let status = manager.get_agent_status(agent_id).await?;
println!("State: {:?}", status.lifecycle.current_state);
println!("Memory: {} bytes", status.memory_allocated);
println!("Uptime: {:?}", status.uptime);
println!("Health: {:?}", status.health_status);
```
### Performance Metrics
Track deployment and operation metrics:
- Deployment duration and success rates
- Hot reload performance and rollback frequency
- Resource utilization per agent
- Message processing latency
- Error rates and failure patterns
## Error Handling and Recovery
### Fault Isolation
The system provides strong isolation guarantees:
- **Process Isolation**: Each agent in separate WASM instance
- **Memory Isolation**: No shared memory between agents
- **Failure Containment**: Failed agents don't affect others
- **Resource Protection**: Limits prevent resource exhaustion
### Recovery Strategies
When agents fail:
1. **Automatic Restart**: Failed agents restarted with exponential backoff
2. **Circuit Breaking**: Repeated failures trigger circuit breaker
3. **Graceful Degradation**: System continues with remaining healthy agents
4. **Rollback**: Automatic rollback to previous working version
### Error Categories
Common failure scenarios and handling:
- **Validation Errors**: WASM module rejected before deployment
- **Resource Exhaustion**: Agent stopped when exceeding limits
- **Runtime Errors**: Agent restarted or marked as failed
- **Deployment Failures**: Rollback to previous stable version
## Best Practices
### Development
- **Validate Early**: Test WASM modules with validator before deployment
- **Resource Planning**: Right-size memory and CPU limits
- **Error Handling**: Implement proper error responses in agents
- **Testing**: Use hot reload for rapid development iteration
### Production
- **Gradual Rollouts**: Use canary deployments for major changes
- **Monitoring**: Track agent health and performance metrics
- **Resource Margins**: Set limits with headroom for growth
- **Backup Strategy**: Maintain previous versions for quick rollback
### Performance
- **Batch Operations**: Group multiple agent operations when possible
- **Resource Reuse**: Pool and reuse WASM instances where appropriate
- **Monitoring Overhead**: Balance observability with performance impact
- **Load Testing**: Validate performance under expected load patterns
## API Reference
### AgentLifecycleManager
```rust
impl AgentLifecycleManager {
// Deploy new agent
async fn deploy_agent(&self, ...) -> Result<DeploymentResult>;
// Update existing agent
async fn hot_reload_agent(&self, ...) -> Result<HotReloadResult>;
// Stop agent gracefully
async fn stop_agent(&self, agent_id: AgentId, timeout: Option<Duration>)
-> Result<OperationResult>;
// Remove agent completely
async fn remove_agent(&self, agent_id: AgentId) -> Result<OperationResult>;
// Get agent status
async fn get_agent_status(&self, agent_id: AgentId) -> Result<AgentStatus>;
// List all agents
async fn list_agents(&self) -> Result<Vec<AgentStatus>>;
}
```
For complete API documentation, see the [API Reference](../developer-guide/api-reference.md).
## Troubleshooting
### Common Issues
**Deployment Failures**
- Check WASM module validation errors
- Verify resource requirements are available
- Ensure agent exports required functions
**Hot Reload Issues**
- Monitor traffic split and rollback triggers
- Check version compatibility requirements
- Verify new version passes health checks
**Performance Problems**
- Review resource limit settings
- Analyze agent message processing patterns
- Check for memory leaks in agent code
**State Transition Errors**
- Ensure proper lifecycle state management
- Check for concurrent operation conflicts
- Review timeout configurations
For additional support, see the [Operational Runbook](operational-runbook.md).