// successfully synced.
	SyncProxyRulesLastTimestamp = metrics.NewGauge(
		&metrics.GaugeOpts{
			Subsystem:      kubeProxySubsystem,
			Name:           "sync_proxy_rules_last_timestamp_seconds",
			Help:           "The last time proxy rules were successfully synced",
			StabilityLevel: metrics.ALPHA,
		},
	)

  maintenance, kube-proxy will take slightly longer to recover from disruptive
  firewalld operations that delete kube-proxy's iptables rules.

  As a side effect of these changes, kube-proxy's
  `sync_proxy_rules_last_timestamp_seconds` metric no longer behaves the
  way it used to; now it will only change when services or endpoints actually
  change, rather than reliably updating every 60 seconds (or whatever). If you