Changes to accommodate client-go changes and kube vendor update

to v1.18.0

Signed-off-by: Humble Chirammal <hchiramm@redhat.com>

vendor/k8s.io/client-go/tools/metrics/metrics.go

@@ -26,6 +26,16 @@ import (
 
 var registerMetrics sync.Once
 
+// DurationMetric is a measurement of some amount of time.
+type DurationMetric interface {
+	Observe(duration time.Duration)
+}
+
+// ExpiryMetric sets some time of expiry. If nil, assume not relevant.
+type ExpiryMetric interface {
+	Set(expiry *time.Time)
+}
+
 // LatencyMetric observes client latency partitioned by verb and url.
 type LatencyMetric interface {
 	Observe(verb string, u url.URL, latency time.Duration)
@@ -37,21 +47,57 @@ type ResultMetric interface {
 }
 
 var (
+	// ClientCertExpiry is the expiry time of a client certificate
+	ClientCertExpiry ExpiryMetric = noopExpiry{}
+	// ClientCertRotationAge is the age of a certificate that has just been rotated.
+	ClientCertRotationAge DurationMetric = noopDuration{}
 	// RequestLatency is the latency metric that rest clients will update.
 	RequestLatency LatencyMetric = noopLatency{}
+	// RateLimiterLatency is the client side rate limiter latency metric.
+	RateLimiterLatency LatencyMetric = noopLatency{}
 	// RequestResult is the result metric that rest clients will update.
 	RequestResult ResultMetric = noopResult{}
 )
 
+// RegisterOpts contains all the metrics to register. Metrics may be nil.
+type RegisterOpts struct {
+	ClientCertExpiry      ExpiryMetric
+	ClientCertRotationAge DurationMetric
+	RequestLatency        LatencyMetric
+	RateLimiterLatency    LatencyMetric
+	RequestResult         ResultMetric
+}
+
 // Register registers metrics for the rest client to use. This can
 // only be called once.
-func Register(lm LatencyMetric, rm ResultMetric) {
+func Register(opts RegisterOpts) {
 	registerMetrics.Do(func() {
-		RequestLatency = lm
-		RequestResult = rm
+		if opts.ClientCertExpiry != nil {
+			ClientCertExpiry = opts.ClientCertExpiry
+		}
+		if opts.ClientCertRotationAge != nil {
+			ClientCertRotationAge = opts.ClientCertRotationAge
+		}
+		if opts.RequestLatency != nil {
+			RequestLatency = opts.RequestLatency
+		}
+		if opts.RateLimiterLatency != nil {
+			RateLimiterLatency = opts.RateLimiterLatency
+		}
+		if opts.RequestResult != nil {
+			RequestResult = opts.RequestResult
+		}
 	})
 }
 
+type noopDuration struct{}
+
+func (noopDuration) Observe(time.Duration) {}
+
+type noopExpiry struct{}
+
+func (noopExpiry) Set(*time.Time) {}
+
 type noopLatency struct{}
 
 func (noopLatency) Observe(string, url.URL, time.Duration) {}