From 090532052939e454287cb2ab09ab3927650a0eca Mon Sep 17 00:00:00 2001
From: Pablo Baeyens <pablo.baeyens@datadoghq.com>
Date: Wed, 26 May 2021 18:26:04 +0200
Subject: [PATCH] Deduplicate hosts for which we send running metrics

---
 exporter/datadogexporter/metrics_translator.go     | 14 +++++++++-----
 .../datadogexporter/metrics_translator_test.go     |  2 +-
 exporter/datadogexporter/translate_traces.go       | 14 +++++++++-----
 exporter/datadogexporter/translate_traces_test.go  |  2 +-
 4 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/exporter/datadogexporter/metrics_translator.go b/exporter/datadogexporter/metrics_translator.go
index 3c6580b51391..f277890315e5 100644
--- a/exporter/datadogexporter/metrics_translator.go
+++ b/exporter/datadogexporter/metrics_translator.go
@@ -255,6 +255,7 @@ func mapHistogramMetrics(name string, slice pdata.HistogramDataPointSlice, bucke
 func mapMetrics(logger *zap.Logger, cfg config.MetricsConfig, prevPts *ttlmap.TTLMap, fallbackHost string, md pdata.Metrics, buildInfo component.BuildInfo) (series []datadog.Metric, droppedTimeSeries int) {
 	pushTime := uint64(time.Now().UTC().UnixNano())
 	rms := md.ResourceMetrics()
+	seenHosts := make(map[string]struct{})
 	for i := 0; i < rms.Len(); i++ {
 		rm := rms.At(i)
 
@@ -270,11 +271,7 @@ func mapMetrics(logger *zap.Logger, cfg config.MetricsConfig, prevPts *ttlmap.TT
 		if !ok {
 			host = fallbackHost
 		}
-
-		// Report the host as running
-		runningMetric := metrics.DefaultMetrics("metrics", host, pushTime, buildInfo)
-
-		series = append(series, runningMetric...)
+		seenHosts[host] = struct{}{}
 
 		ilms := rm.InstrumentationLibraryMetrics()
 		for j := 0; j < ilms.Len(); j++ {
@@ -317,5 +314,12 @@ func mapMetrics(logger *zap.Logger, cfg config.MetricsConfig, prevPts *ttlmap.TT
 			}
 		}
 	}
+
+	for host := range seenHosts {
+		// Report the host as running
+		runningMetric := metrics.DefaultMetrics("metrics", host, pushTime, buildInfo)
+		series = append(series, runningMetric...)
+	}
+
 	return
 }
diff --git a/exporter/datadogexporter/metrics_translator_test.go b/exporter/datadogexporter/metrics_translator_test.go
index e2b9952023cf..5946656f5f30 100644
--- a/exporter/datadogexporter/metrics_translator_test.go
+++ b/exporter/datadogexporter/metrics_translator_test.go
@@ -556,7 +556,7 @@ func TestRunningMetrics(t *testing.T) {
 
 	assert.ElementsMatch(t,
 		runningHostnames,
-		[]string{"fallbackHostname", "resource-hostname-1", "resource-hostname-1", "resource-hostname-2"},
+		[]string{"fallbackHostname", "resource-hostname-1", "resource-hostname-2"},
 	)
 
 }
diff --git a/exporter/datadogexporter/translate_traces.go b/exporter/datadogexporter/translate_traces.go
index 0030a87bd3ac..3e85e4bb1262 100644
--- a/exporter/datadogexporter/translate_traces.go
+++ b/exporter/datadogexporter/translate_traces.go
@@ -73,7 +73,8 @@ func convertToDatadogTd(td pdata.Traces, fallbackHost string, cfg *config.Config
 
 	var traces []*pb.TracePayload
 
-	var runningMetrics []datadog.Metric
+	seenHosts := make(map[string]struct{})
+	var series []datadog.Metric
 	pushTime := pdata.TimestampFromTime(time.Now())
 	for i := 0; i < resourceSpans.Len(); i++ {
 		rs := resourceSpans.At(i)
@@ -81,15 +82,18 @@ func convertToDatadogTd(td pdata.Traces, fallbackHost string, cfg *config.Config
 		if !ok {
 			host = fallbackHost
 		}
-
+		seenHosts[host] = struct{}{}
 		payload := resourceSpansToDatadogSpans(rs, host, cfg, blk)
 		traces = append(traces, &payload)
+	}
 
-		ms := metrics.DefaultMetrics("traces", host, uint64(pushTime), buildInfo)
-		runningMetrics = append(runningMetrics, ms...)
+	for host := range seenHosts {
+		// Report the host as running
+		runningMetric := metrics.DefaultMetrics("traces", host, uint64(pushTime), buildInfo)
+		series = append(series, runningMetric...)
 	}
 
-	return traces, runningMetrics
+	return traces, series
 }
 
 func aggregateTracePayloadsByEnv(tracePayloads []*pb.TracePayload) []*pb.TracePayload {
diff --git a/exporter/datadogexporter/translate_traces_test.go b/exporter/datadogexporter/translate_traces_test.go
index 28193b3ccd69..be2108ae479c 100644
--- a/exporter/datadogexporter/translate_traces_test.go
+++ b/exporter/datadogexporter/translate_traces_test.go
@@ -191,7 +191,7 @@ func TestRunningTraces(t *testing.T) {
 
 	assert.ElementsMatch(t,
 		runningHostnames,
-		[]string{"resource-hostname-1", "resource-hostname-1", "resource-hostname-2", "fallbackHost"},
+		[]string{"resource-hostname-1", "resource-hostname-2", "fallbackHost"},
 	)
 }