---
title: "High_availability"
description: "Documentation for High_availability"
---
[AIR-3][AIS-3][BPC-3][RES-3]
# High Availability System \[AIR-3\]\[AIS-3\]\[RES-3\]\[SCL-3\]
## Table of Contents
- [Section 1](#section-1)
- [Section 2](#section-2)
This document describes the High Availability (HA) subsystem of Anya Core, detailing the architecture, components, and operational characteristics that ensure continuous operation even in the face of failures.
## Overview
The High Availability subsystem provides fault tolerance, automatic failover, and resilience capabilities to Anya Core. It implements a distributed coordination mechanism that ensures service continuity even when individual nodes or components fail.
## Architecture
The HA system follows the hexagonal architecture pattern defined by official Bitcoin Improvement Proposals (BIPs):
```
+----------------+
| Cluster API |
+-------+--------+
|
+----------------+ +-----v--------+ +----------------+
| (DNS, K8s, etc)| | | | (Prometheus) |
+----------------+ +-------+------+ +----------------+
|
+-------v--------+
| Node Management|
| & Health Checks|
+----------------+
```
## Key Components \[AIR-3\]
### Cluster Manager
The `ClusterManager` is the central component of the High Availability subsystem. It manages:
- Node discovery and registration
- Leader election
- Health monitoring
- Fault detection
- Automatic failover
- Configuration synchronization
```rust
/// Cluster Manager for high availability operations
/// \[AIR-3\]\[RES-3\]\[SCL-3\]
pub struct ClusterManager {
config: ClusterConfig,
nodes: HashMap<NodeId, NodeInfo>,
current_leader: Option<NodeId>,
status: ClusterStatus,
}
```
### Node Discovery Services \[AIR-3\]
Multiple node discovery mechanisms are supported:
1. **Static Configuration**: Pre-configured list of nodes
2. **DNS Discovery**: SRV record-based discovery
3. **Kubernetes Discovery**: Kubernetes API-based discovery
4. **Multicast Discovery**: Local network discovery via multicast
### Membership Service \[RES-3\]
The Membership Service tracks node status and manages:
- Node join/leave operations
- Health check protocols
- Heartbeat monitoring
- Split-brain detection
- Quorum-based decisions
### Health Monitoring \[RES-3\]
Comprehensive health monitoring includes:
- Regular heartbeat checks
- Application-level health probes
- Resource utilization monitoring
- Response time measurements
- Error rate tracking
## Leader Election \[AIR-3\]\[RES-3\]
The leader election algorithm is based on the Raft consensus protocol with the following properties:
1. **Safety**: At most one leader can be elected in a given term
2. **Liveness**: A new leader will eventually be elected if the current one fails
3. **Fault Tolerance**: The system can tolerate up to (N-1)/2 node failures
The election process follows these steps:
1. All nodes start in follower state
2. If a follower receives no communication, it becomes a candidate
3. A candidate requests votes from other nodes
4. Nodes vote for at most one candidate per term
5. A candidate becomes the leader if it receives votes from a majority of nodes
## Fault Detection and Recovery \[RES-3\]
The system detects and handles various failure scenarios:
| Node Crash | Missed heartbeats | Leader election |
| Network Partition | Quorum loss | Partition healing |
| Performance Degradation | Slow response time | Load balancing |
| Resource Exhaustion | Resource metrics | Auto-scaling |
| Application Errors | Error rate increase | Restart service |
## Configuration Synchronization \[AIR-3\]
The HA subsystem ensures configuration consistency across the cluster:
1. Leader maintains the authoritative configuration
2. Configuration changes are propagated to all nodes
3. Version tracking prevents conflicts
4. Two-phase commit ensures atomic updates
5. Roll-back capability for failed updates
## Security Considerations \[AIS-3\]
The HA system implements these security measures:
1. **TLS Mutual Authentication**: All node-to-node communication is encrypted and authenticated
2. **Authorization**: Role-based access control for administrative operations
3. **Audit Logging**: All cluster operations are logged with tamper-evident records
4. **Network Isolation**: Control plane traffic is isolated from data plane
5. **Secure Bootstrap**: Nodes are securely provisioned with initial credentials
## Performance Characteristics \[AIP-3\]
The HA subsystem is designed for optimal performance:
- Low-latency leader election (<500ms in typical conditions)
- Efficient heartbeat protocol with minimal network overhead
- Scalable to 100+ nodes without significant performance degradation
- Configurable monitoring intervals based on deployment requirements
- Low CPU and memory footprint (<5% of system resources)
## Bitcoin-Specific Considerations \[AIR-3\]\[AIS-3\]
For Bitcoin operations, the HA system provides additional guarantees:
1. **Transaction Consistency**: Ensures no double-spending during failover
2. **UTXO Set Integrity**: Maintains consistent UTXO references across nodes
3. **Blockchain State**: Synchronizes blockchain view across all nodes
4. **HSM Coordination**: Manages distributed HSM operations securely
5. **DLC Contract Continuity**: Ensures DLC contracts remain valid during failover
## Usage Examples
### Basic HA Cluster Configuration
```rust
let config = ClusterConfig {
node_id: "node-1".to_string(),
discovery_method: DiscoveryMethod::Static {
nodes: vec!["node-1:7800".to_string(), "node-2:7800".to_string(), "node-3:7800".to_string()],
},
bind_address: "0.0.0.0:7800".to_string(),
heartbeat_interval: Duration::from_secs(1),
election_timeout: Duration::from_secs(5),
..Default::default()
};
let cluster_manager = ClusterManager::new(config);
cluster_manager.initialize().await?;
cluster_manager.join_cluster().await?;
// Get cluster status
let status = cluster_manager.get_status().await?;
println!("Current leader: {:?}", status.current_leader);
println!("Cluster nodes: {:?}", status.nodes);
```
### Custom Health Check Configuration
```rust
let health_config = HealthCheckConfig {
checks: vec![
HealthCheck::Http {
name: "api".to_string(),
url: "http://localhost:8080/health".to_string(),
interval: Duration::from_secs(5),
timeout: Duration::from_secs(1),
expected_status: 200,
},
HealthCheck::Custom {
name: "bitcoin-sync".to_string(),
command: Box::new(|ctx| {
Box::pin(async move {
// Check Bitcoin synchronization status
let bitcoin_client = ctx.get_service::<BitcoinClient>().unwrap();
let sync_status = bitcoin_client.get_sync_status().await?;
Ok(sync_status.blocks_remaining < 10)
})
}),
interval: Duration::from_secs(30),
},
],
aggregation: HealthAggregation::All,
};
cluster_manager.configure_health_checks(health_config).await?;
```
## Testing and Verification \[AIT-3\]
The HA subsystem undergoes rigorous testing:
1. **Unit Tests**: All components have comprehensive unit tests
2. **Chaos Testing**: Random node failures are simulated
3. **Network Partition Testing**: Various network partition scenarios
4. **Performance Testing**: Behavior under load and stress conditions
5. **Long-running Tests**: Stability verification over extended periods
## Future Enhancements
Planned improvements to the HA subsystem include:
1. **Geo-distributed Clustering**: Support for multi-region deployments
2. **Automatic Scaling**: Dynamic node addition/removal based on load
3. **Enhanced Observability**: Advanced metrics and diagnostics
4. **Custom Consensus Protocols**: Pluggable consensus mechanisms
5. **Integrated Backup Management**: Automated backup and restore
## References
1. Official Bitcoin Improvement Proposals (BIPs)
2. Raft Consensus Algorithm
3. Kubernetes Operator Framework
4. Prometheus Monitoring System
5. BFT Consensus Algorithms
## Last Updated
2025-03-12
## See Also
- [Related Document](#related-document)