SignalDB Service Discovery

Capability-Based Routing

Services register with specific capabilities for automatic routing:

ServiceBootstrap Pattern

Every service uses ServiceBootstrap at startup:

1. •Connects to service catalog (SQLite or PostgreSQL from [discovery] or [database] DSN)
2. •Generates unique UUID service_id
3. •Registers in ingesters table with service_type, address, capabilities (comma-separated)
4. •Spawns background heartbeat task updating last_seen
5. •On shutdown: deregisters and stops heartbeat

let bootstrap = ServiceBootstrap::new(config).await?;
bootstrap.register().await?;
// ... service runs ...
// Automatic deregistration on drop/shutdown

Service Catalog Schema

CREATE TABLE ingesters (
    id UUID PRIMARY KEY,
    address TEXT NOT NULL,
    last_seen TIMESTAMP WITH TIME ZONE,
    stopped_at TIMESTAMP WITH TIME ZONE
);

Discovery Mechanism

• •InMemoryFlightTransport: Connection pooling (max 50 connections, 30s timeout, 5min expiry) + capability-based client lookup
• •ServiceRegistry (Router-specific): Cached HashMap of services, polls catalog at configurable interval
• •Service selection: Currently picks first available (round-robin planned)
• •TTL-based cleanup: Stale services auto-removed

Configuration

[database]
dsn = "sqlite://.data/signaldb.db"

[discovery]
dsn = "sqlite://.data/signaldb.db"   # Falls back to [database].dsn
heartbeat_interval = "30s"
poll_interval = "60s"
ttl = "300s"

Key Implementation Files