feat(monitors): public heartbeat ping endpoints, header token, log masking and sweeper

server/internal/metricsched/scheduler.go

@@ -0,0 +1,40 @@
+// Package metricsched sweeps passive monitors - heartbeats and, from phase 2,
+// metric monitors - on a fixed tick. Nothing here runs a check: it reads what
+// pings and agents already delivered and decides what is overdue or breaching.
+package metricsched
+
+import (
+	"context"
+	"log"
+	"time"
+
+	"gitea.hostxtra.co.uk/mrhid6/vantage/server/internal/services"
+)
+
+const tick = 30 * time.Second
+
+func Start(ctx context.Context) {
+	go func() {
+		t := time.NewTicker(tick)
+		defer t.Stop()
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case now := <-t.C:
+				sweep(now)
+			}
+		}
+	}()
+}
+
+// sweep recovers per sweep so one bad document cannot stop alerting for the
+// whole instance until the next deploy.
+func sweep(now time.Time) {
+	defer func() {
+		if r := recover(); r != nil {
+			log.Printf("metricsched: sweep panic: %v", r)
+		}
+	}()
+	services.SweepHeartbeats(now)
+}