Making metrics TTL configurable per instance of metric store

Avoiding the global var and making metrics TTL configurable per
metric store

Signed-off-by: Muhammad Muaaz Saleem <muhammad.muaaz.saleem@zalando.de>

pkg/provider/hpa.go

@@ -81,10 +81,12 @@ func NewHPAProvider(client kubernetes.Interface, interval, collectorInterval tim
 		interval:          interval,
 		collectorInterval: collectorInterval,
 		metricSink:        metricsc,
-		metricStore:       NewMetricStore(),
-		collectorFactory:  collectorFactory,
-		recorder:          recorder.CreateEventRecorder(client),
-		logger:            log.WithFields(log.Fields{"provider": "hpa"}),
+		metricStore: NewMetricStore(func() time.Time {
+			return time.Now().UTC().Add(15 * time.Minute)
+		}),
+		collectorFactory: collectorFactory,
+		recorder:         recorder.CreateEventRecorder(client),
+		logger:           log.WithFields(log.Fields{"provider": "hpa"}),
 	}
 }
 

pkg/provider/metric_store.go

@@ -34,18 +34,16 @@ type externalMetricsStoredMetric struct {
 type MetricStore struct {
 	customMetricsStore   map[string]map[schema.GroupResource]map[string]map[string]customMetricsStoredMetric
 	externalMetricsStore map[string]map[string]externalMetricsStoredMetric
+	metricsTTLCalculator func() time.Time
 	sync.RWMutex
 }
 
-var metricsTTL = func() time.Time {
-	return time.Now().UTC().Add(15 * time.Minute)
-}
-
 // NewMetricStore initializes an empty Metrics Store.
-func NewMetricStore() *MetricStore {
+func NewMetricStore(ttlCalculator func() time.Time) *MetricStore {
 	return &MetricStore{
 		customMetricsStore:   make(map[string]map[schema.GroupResource]map[string]map[string]customMetricsStoredMetric, 0),
 		externalMetricsStore: make(map[string]map[string]externalMetricsStoredMetric, 0),
+		metricsTTLCalculator: ttlCalculator,
 	}
 }
 
@@ -81,7 +79,7 @@ func (s *MetricStore) insertCustomMetric(value custom_metrics.MetricValue, label
 	metric := customMetricsStoredMetric{
 		Value:  value,
 		Labels: labels,
-		TTL:    metricsTTL(), // TODO: make metricsTTL configurable
+		TTL:    s.metricsTTLCalculator(), // TODO: make TTL configurable
 	}
 
 	metrics, ok := s.customMetricsStore[value.MetricName]
@@ -122,7 +120,7 @@ func (s *MetricStore) insertExternalMetric(metric external_metrics.ExternalMetri
 
 	storedMetric := externalMetricsStoredMetric{
 		Value: metric,
-		TTL:   metricsTTL(), // TODO: make metricsTTL configurable
+		TTL:   s.metricsTTLCalculator(), // TODO: make TTL configurable
 	}
 
 	labelsKey := hashLabelMap(metric.MetricLabels)

pkg/provider/metrics_store_test.go

@@ -6,7 +6,6 @@ import (
 	"github.com/zalando-incubator/kube-metrics-adapter/pkg/collector"
 	"k8s.io/api/autoscaling/v2beta1"
 	"k8s.io/apimachinery/pkg/api/resource"
-	"k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/labels"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/types"
@@ -128,7 +127,9 @@ func TestInternalMetricStorage(t *testing.T) {
 
 	for _, tc := range metricStoreTests {
 		t.Run(tc.test, func(t *testing.T) {
-			metricsStore := NewMetricStore()
+			metricsStore := NewMetricStore(func() time.Time {
+				return time.Now().UTC().Add(15 * time.Minute)
+			})
 
 			// Insert a metric with value
 			metricsStore.Insert(tc.insert)
@@ -186,7 +187,9 @@ func TestExternalMetricStorage(t *testing.T) {
 
 	for _, tc := range metricStoreTests {
 		t.Run(tc.test, func(t *testing.T) {
-			metricsStore := NewMetricStore()
+			metricsStore := NewMetricStore(func() time.Time {
+				return time.Now().UTC().Add(15 * time.Minute)
+			})
 
 			// Insert a metric with value
 			metricsStore.Insert(tc.insert)
@@ -206,13 +209,10 @@ func TestExternalMetricStorage(t *testing.T) {
 }
 
 func TestMetricsExpiration(t *testing.T) {
-	metricStore := NewMetricStore()
-
 	// Temporarily Override global TTL to test expiration
-	tmpTTL := metricsTTL
-	metricsTTL = func() time.Time {
+	metricStore := NewMetricStore(func() time.Time {
 		return time.Now().UTC().Add(time.Hour * -1)
-	}
+	})
 
 	customMetric := collector.CollectedMetric{
 		Type: v2beta1.MetricSourceType("Object"),
@@ -224,7 +224,6 @@ func TestMetricsExpiration(t *testing.T) {
 				Kind:       "Node",
 				APIVersion: "core/v1",
 			},
-			Timestamp: v1.Time{Time: metricsTTL()},
 		},
 	}
 
@@ -233,7 +232,6 @@ func TestMetricsExpiration(t *testing.T) {
 		External: external_metrics.ExternalMetricValue{
 			MetricName: "metric-per-unit",
 			Value:      *resource.NewQuantity(0, ""),
-			Timestamp:  v1.Time{Time: metricsTTL()},
 		},
 	}
 
@@ -248,12 +246,12 @@ func TestMetricsExpiration(t *testing.T) {
 	externalMetricInfos := metricStore.ListAllExternalMetrics()
 	require.Len(t, externalMetricInfos, 0)
 
-	// set metricTTL to original
-	metricsTTL = tmpTTL
 }
 
 func TestMetricsNonExpiration(t *testing.T) {
-	metricStore := NewMetricStore()
+	metricStore := NewMetricStore(func() time.Time {
+		return time.Now().UTC().Add(15 * time.Minute)
+	})
 
 	customMetric := collector.CollectedMetric{
 		Type: v2beta1.MetricSourceType("Object"),