From 3f1b120eda41e631ba345c0e71c8ee3cbebfcc35 Mon Sep 17 00:00:00 2001
From: Nail Islamov <nislamov@atlassian.com>
Date: Wed, 28 Nov 2018 12:13:07 +1100
Subject: [PATCH 1/2] Add a flag `metrics-start-duration`

---
 cmd/adapter/adapter.go               | 7 ++++++-
 pkg/custom-provider/provider.go      | 6 ++++--
 pkg/custom-provider/provider_test.go | 3 ++-
 3 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/cmd/adapter/adapter.go b/cmd/adapter/adapter.go
index 19731222e..37c738d5d 100644
--- a/cmd/adapter/adapter.go
+++ b/cmd/adapter/adapter.go
@@ -53,6 +53,8 @@ type PrometheusAdapter struct {
 	AdapterConfigFile string
 	// MetricsRelistInterval is the interval at which to relist the set of available metrics
 	MetricsRelistInterval time.Duration
+	// MetricsMaxAge is the period to query available metrics for
+	MetricsMaxAge time.Duration
 
 	metricsConfig *adaptercfg.MetricsDiscoveryConfig
 }
@@ -83,6 +85,8 @@ func (cmd *PrometheusAdapter) addFlags() {
 			"and custom metrics API resources")
 	cmd.Flags().DurationVar(&cmd.MetricsRelistInterval, "metrics-relist-interval", cmd.MetricsRelistInterval, ""+
 		"interval at which to re-list the set of all available metrics from Prometheus")
+	cmd.Flags().DurationVar(&cmd.MetricsMaxAge, "metrics-max-age", cmd.MetricsMaxAge, ""+
+		"period for which to query the set of available metrics from Prometheus")
 }
 
 func (cmd *PrometheusAdapter) loadConfig() error {
@@ -122,7 +126,7 @@ func (cmd *PrometheusAdapter) makeProvider(promClient prom.Client, stopCh <-chan
 	}
 
 	// construct the provider and start it
-	cmProvider, runner := cmprov.NewPrometheusProvider(mapper, dynClient, promClient, namers, cmd.MetricsRelistInterval)
+	cmProvider, runner := cmprov.NewPrometheusProvider(mapper, dynClient, promClient, namers, cmd.MetricsRelistInterval, cmd.MetricsMaxAge)
 	runner.RunUntil(stopCh)
 
 	return cmProvider, nil
@@ -173,6 +177,7 @@ func main() {
 	cmd := &PrometheusAdapter{
 		PrometheusURL:         "https://localhost",
 		MetricsRelistInterval: 10 * time.Minute,
+		MetricsMaxAge:         20 * time.Minute,
 	}
 	cmd.Name = "prometheus-metrics-adapter"
 	cmd.addFlags()
diff --git a/pkg/custom-provider/provider.go b/pkg/custom-provider/provider.go
index 96f8831cc..afd59ac94 100644
--- a/pkg/custom-provider/provider.go
+++ b/pkg/custom-provider/provider.go
@@ -55,9 +55,10 @@ type prometheusProvider struct {
 	SeriesRegistry
 }
 
-func NewPrometheusProvider(mapper apimeta.RESTMapper, kubeClient dynamic.Interface, promClient prom.Client, namers []MetricNamer, updateInterval time.Duration) (provider.CustomMetricsProvider, Runnable) {
+func NewPrometheusProvider(mapper apimeta.RESTMapper, kubeClient dynamic.Interface, promClient prom.Client, namers []MetricNamer, updateInterval time.Duration, maxAge time.Duration) (provider.CustomMetricsProvider, Runnable) {
 	lister := &cachingMetricsLister{
 		updateInterval: updateInterval,
+		maxAge:         maxAge,
 		promClient:     promClient,
 		namers:         namers,
 
@@ -191,6 +192,7 @@ type cachingMetricsLister struct {
 
 	promClient     prom.Client
 	updateInterval time.Duration
+	maxAge         time.Duration
 	namers         []MetricNamer
 }
 
@@ -212,7 +214,7 @@ type selectorSeries struct {
 }
 
 func (l *cachingMetricsLister) updateMetrics() error {
-	startTime := pmodel.Now().Add(-1 * l.updateInterval)
+	startTime := pmodel.Now().Add(-1 * l.maxAge)
 
 	// don't do duplicate queries when it's just the matchers that change
 	seriesCacheByQuery := make(map[prom.Selector][]prom.Series)
diff --git a/pkg/custom-provider/provider_test.go b/pkg/custom-provider/provider_test.go
index dd08f978f..29abe0380 100644
--- a/pkg/custom-provider/provider_test.go
+++ b/pkg/custom-provider/provider_test.go
@@ -32,6 +32,7 @@ import (
 )
 
 const fakeProviderUpdateInterval = 2 * time.Second
+const fakeProviderStartDuration = 2 * time.Second
 
 func setupPrometheusProvider() (provider.CustomMetricsProvider, *fakeprom.FakePrometheusClient) {
 	fakeProm := &fakeprom.FakePrometheusClient{}
@@ -41,7 +42,7 @@ func setupPrometheusProvider() (provider.CustomMetricsProvider, *fakeprom.FakePr
 	namers, err := NamersFromConfig(cfg, restMapper())
 	Expect(err).NotTo(HaveOccurred())
 
-	prov, _ := NewPrometheusProvider(restMapper(), fakeKubeClient, fakeProm, namers, fakeProviderUpdateInterval)
+	prov, _ := NewPrometheusProvider(restMapper(), fakeKubeClient, fakeProm, namers, fakeProviderUpdateInterval, fakeProviderStartDuration)
 
 	containerSel := prom.MatchSeries("", prom.NameMatches("^container_.*"), prom.LabelNeq("container_name", "POD"), prom.LabelNeq("namespace", ""), prom.LabelNeq("pod_name", ""))
 	namespacedSel := prom.MatchSeries("", prom.LabelNeq("namespace", ""), prom.NameNotMatches("^container_.*"))

From 88c0ad0b6aafb85014b2a1fa35667879828610eb Mon Sep 17 00:00:00 2001
From: Nail Islamov <nislamov@atlassian.com>
Date: Wed, 28 Nov 2018 12:20:09 +1100
Subject: [PATCH 2/2] Add validation

---
 cmd/adapter/adapter.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/cmd/adapter/adapter.go b/cmd/adapter/adapter.go
index 37c738d5d..1a31253f9 100644
--- a/cmd/adapter/adapter.go
+++ b/cmd/adapter/adapter.go
@@ -109,6 +109,10 @@ func (cmd *PrometheusAdapter) makeProvider(promClient prom.Client, stopCh <-chan
 		return nil, nil
 	}
 
+	if cmd.MetricsMaxAge < cmd.MetricsRelistInterval {
+		return nil, fmt.Errorf("max age must not be less than relist interval")
+	}
+
 	// grab the mapper and dynamic client
 	mapper, err := cmd.RESTMapper()
 	if err != nil {