Real-Time Monitoring

SLOzy provides WebSocket-based real-time monitoring through internal/websocket/.

Architecture

The WebSocket system uses a Hub pattern:

Client → WebSocket Upgrade → Hub (register/broadcast) → Subscribed Clients

• Hub — Central message router (hub.go) managing client registration, subscriptions, and broadcasts.
• Client — Represents a single WebSocket connection with a send channel and subscription map.
• Subscription — Associates a client with an SLO ID and update channels (e.g., status, metrics).

Connecting

const ws = new WebSocket("wss://slozy.example.com/ws");

ws.onopen = () => {
  // Subscribe to SLO updates
  ws.send(JSON.stringify({
    type: "subscribe",
    data: { slo_id: 1, channels: ["status", "metrics"] }
  }));
};

Message Types

Type	Direction	Description
subscribe	Client → Server	Subscribe to SLO updates for a specific SLO ID
unsubscribe	Client → Server	Unsubscribe from SLO updates
ping / pong	Bidirectional	Keep-alive (server pings every 54s, read deadline 60s)
Broadcasts	Server → Client	Pushed metrics, status changes, and alerts

SLOCalculationService

internal/prometheus/calculator.go powers the real-time metrics via GetRealTimeMetrics():

calcReq := &models.SLOCalculationRequest{
    SLOID:      slo.ID,
    TimeWindow: "5m",
}

This queries Prometheus every evaluation cycle and pushes results to subscribed WebSocket clients through Hub.BroadcastToSLO(sloID, "metric_update", data).

Broadcasting

// Broadcast to all subscribers of an SLO
hub.BroadcastToSLO(sloID, "metric_update", map[string]interface{}{
    "current_value":   99.92,
    "error_budget":    15.3,
    "status":          "healthy",
})

Statistics

The Hub exposes GetStatistics() returning connected clients, total subscriptions, clients per SLO, and message queue length.