Instrument transformer.go with latency metrics.

test/integration/master/transformation_testcase.go

@@ -29,6 +29,7 @@ import (
 
 	"github.com/coreos/etcd/clientv3"
 	"github.com/ghodss/yaml"
+	"github.com/prometheus/client_golang/prometheus"
 
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -42,11 +43,12 @@ import (
 )
 
 const (
-	secretKey                = "api_key"
-	secretVal                = "086a7ffc-0225-11e8-ba89-0ed5f89f718b"
-	encryptionConfigFileName = "encryption.conf"
-	testNamespace            = "secret-encryption-test"
-	testSecret               = "test-secret"
+	secretKey                   = "api_key"
+	secretVal                   = "086a7ffc-0225-11e8-ba89-0ed5f89f718b"
+	encryptionConfigFileName    = "encryption.conf"
+	testNamespace               = "secret-encryption-test"
+	testSecret                  = "test-secret"
+	latencySummaryMetricsFamily = "value_storage_transformation_latency_microseconds"
 )
 
 type unSealSecret func(cipherText []byte, ctx value.Context, config encryptionconfig.ProviderConfig) ([]byte, error)
@@ -237,3 +239,31 @@ func (e *transformTest) readRawRecordFromETCD(path string) (*clientv3.GetRespons
 
 	return response, nil
 }
+
+func (e *transformTest) printMetrics() error {
+	metrics, err := prometheus.DefaultGatherer.Gather()
+	if err != nil {
+		return fmt.Errorf("failed to gather metrics: %s", err)
+	}
+
+	metricsOfInterest := []string{latencySummaryMetricsFamily}
+
+	for _, mf := range metrics {
+		if contains(metricsOfInterest, *mf.Name) {
+			for _, metric := range mf.GetMetric() {
+				e.logger.Logf("%v", metric)
+			}
+		}
+	}
+
+	return nil
+}
+
+func contains(s []string, e string) bool {
+	for _, a := range s {
+		if a == e {
+			return true
+		}
+	}
+	return false
+}