From 91645514597b0dcff19b14d6344934b60c23764c Mon Sep 17 00:00:00 2001
From: Vishal Raj <vishal.raj@elastic.co>
Date: Wed, 8 May 2024 18:28:07 +0100
Subject: [PATCH] Add configuration option for remapping otel metrics

---
 input/otlp/consumer.go           | 18 +++++++++++++-----
 input/otlp/hostmetrics/memory.go |  8 +++++---
 input/otlp/metrics.go            | 14 ++++++++------
 3 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/input/otlp/consumer.go b/input/otlp/consumer.go
index 9716c6fb..b6fea898 100644
--- a/input/otlp/consumer.go
+++ b/input/otlp/consumer.go
@@ -46,6 +46,10 @@ type ConsumerConfig struct {
 	// Semaphore holds a semaphore on which Processor.HandleStream will acquire a
 	// token before proceeding, to limit concurrency.
 	Semaphore input.Semaphore
+
+	// RemapOTelMetrics remaps certain OpenTelemetry metrics to elastic metrics.
+	// Note that both, OTel and Elastic, metrics would be published.
+	RemapOTelMetrics bool
 }
 
 // Consumer transforms OpenTelemetry data to the Elastic APM data model,
@@ -64,12 +68,16 @@ func NewConsumer(config ConsumerConfig) *Consumer {
 	} else {
 		config.Logger = config.Logger.Named("otel")
 	}
-	return &Consumer{
-		config: config,
-		sem:    config.Semaphore,
-		remappers: []remapper{
+	var remappers []remapper
+	if config.RemapOTelMetrics {
+		remappers = []remapper{
 			hostmetrics.NewRemapper(config.Logger),
-		},
+		}
+	}
+	return &Consumer{
+		config:    config,
+		sem:       config.Semaphore,
+		remappers: remappers,
 	}
 }
 
diff --git a/input/otlp/hostmetrics/memory.go b/input/otlp/hostmetrics/memory.go
index a080823d..1f18a93c 100644
--- a/input/otlp/hostmetrics/memory.go
+++ b/input/otlp/hostmetrics/memory.go
@@ -10,10 +10,12 @@ func remapMemoryMetrics(src, out pmetric.MetricSlice, dataset string) error {
 	var total, free, cached, usedBytes, actualFree, actualUsedBytes int64
 	var usedPercent, actualUsedPercent float64
 
-	// iterate all metrics in the current scope and generate the additional Elastic system integration metrics
+	// iterate all metrics in the current scope and generate the additional Elastic system
+	// integration metrics
 	for i := 0; i < src.Len(); i++ {
 		metric := src.At(i)
-		// TODO (lahisvjar): If system.memory.utilization is not present then derive it from system.memory.usage
+		// TODO (lahisvjar): If system.memory.utilization is not present then derive it from
+		// system.memory.usage.
 		if metric.Name() == "system.memory.usage" {
 			dataPoints := metric.Sum().DataPoints()
 			for j := 0; j < dataPoints.Len(); j++ {
@@ -29,7 +31,7 @@ func remapMemoryMetrics(src, out pmetric.MetricSlice, dataset string) error {
 						total += value
 					case "free":
 						// TODO (lahsivjar): if system.linux.memory.available is present then use it for
-						// free mem calculation
+						// free mem calculation.
 						free = value
 						usedBytes -= value
 						total += value
diff --git a/input/otlp/metrics.go b/input/otlp/metrics.go
index e1fa3a9b..a7189c9d 100644
--- a/input/otlp/metrics.go
+++ b/input/otlp/metrics.go
@@ -146,12 +146,14 @@ func (c *Consumer) handleScopeMetrics(
 	// Handle remapping if any. Remapped metrics will be added to a new
 	// metric slice and then processed as any other metric in the scope.
 	// TODO (lahsivjar): Possible to approximate capacity of the slice?
-	remappedMetrics := pmetric.NewMetricSlice()
-	for _, r := range c.remappers {
-		r.Remap(in, remappedMetrics)
-	}
-	for i := 0; i < remappedMetrics.Len(); i++ {
-		c.addMetric(remappedMetrics.At(i), ms, remainingDataPoints, remainingMetrics)
+	if len(c.remappers) > 0 {
+		remappedMetrics := pmetric.NewMetricSlice()
+		for _, r := range c.remappers {
+			r.Remap(in, remappedMetrics)
+		}
+		for i := 0; i < remappedMetrics.Len(); i++ {
+			c.addMetric(remappedMetrics.At(i), ms, remainingDataPoints, remainingMetrics)
+		}
 	}
 	// Process all the metrics added to the metricset.
 	for key, ms := range ms {