token cache: make fetch_total a counter

Downstreams assume process restarts when counters decrement. Currently,
the "active" label is expected to decrement but the "ok" and "error"
labels are intended to be handled as counters. This is unneccesary and
hard to deal with. This changes consolidate "blocking" and "in_flight"
tracking into a single guage, which allows fetch completion to be a pure
counter.

Kubernetes-commit: dc5934f58456d95b0264665871c0c48e16ee6469

pkg/authentication/token/cache/stats.go

@@ -42,8 +42,8 @@ var (
 		},
 		[]string{"status"},
 	)
-	fetchCount = metrics.NewGaugeVec(
-		&metrics.GaugeOpts{
+	fetchCount = metrics.NewCounterVec(
+		&metrics.CounterOpts{
 			Namespace:      "authentication",
 			Subsystem:      "token_cache",
 			Name:           "fetch_total",
@@ -51,13 +51,14 @@ var (
 		},
 		[]string{"status"},
 	)
-	blockCount = metrics.NewGauge(
+	activeFetchCount = metrics.NewGaugeVec(
 		&metrics.GaugeOpts{
 			Namespace:      "authentication",
 			Subsystem:      "token_cache",
-			Name:           "block_count",
+			Name:           "active_fetch_count",
 			StabilityLevel: metrics.ALPHA,
 		},
+		[]string{"status"},
 	)
 )
 
@@ -66,7 +67,7 @@ func init() {
 		requestLatency,
 		requestCount,
 		fetchCount,
-		blockCount,
+		activeFetchCount,
 	)
 }
 
@@ -74,9 +75,11 @@ const (
 	hitTag  = "hit"
 	missTag = "miss"
 
-	fetchActiveTag = "active"
 	fetchFailedTag = "error"
 	fetchOkTag     = "ok"
+
+	fetchInFlightTag = "in_flight"
+	fetchBlockedTag  = "blocked"
 )
 
 type statsCollector struct{}
@@ -101,12 +104,12 @@ func (statsCollector) authenticating() func(hit bool) {
 }
 
 func (statsCollector) blocking() func() {
-	blockCount.Inc()
-	return blockCount.Dec
+	activeFetchCount.WithLabelValues(fetchBlockedTag).Inc()
+	return activeFetchCount.WithLabelValues(fetchBlockedTag).Dec
 }
 
 func (statsCollector) fetching() func(ok bool) {
-	fetchCount.WithLabelValues(fetchActiveTag).Inc()
+	activeFetchCount.WithLabelValues(fetchInFlightTag).Inc()
 	return func(ok bool) {
 		var tag string
 		if ok {
@@ -115,6 +118,8 @@ func (statsCollector) fetching() func(ok bool) {
 			tag = fetchFailedTag
 		}
 
-		fetchCount.WithLabelValues(tag).Dec()
+		fetchCount.WithLabelValues(tag).Inc()
+
+		activeFetchCount.WithLabelValues(fetchInFlightTag).Dec()
 	}
 }