From 84344fb1a273ed1c25423e46a654f9af273636f8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C4=90=E1=BB=97=20Tr=E1=BB=8Dng=20H=E1=BA=A3i?=
 <41283691+hainenber@users.noreply.github.com>
Date: Mon, 27 Nov 2023 21:22:08 +0700
Subject: [PATCH] fix(otelcol/fanoutconsumer): nil check during fanout consumer
 creation (#5854)

Signed-off-by: hainenber <dotronghai96@gmail.com>
---
 CHANGELOG.md                                      |  2 ++
 component/otelcol/internal/fanoutconsumer/logs.go | 14 ++++++++++----
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 048ba98797bb..1f2e8bcd2680 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -48,6 +48,8 @@ Main (unreleased)
 
 - Fix issue with windows_exporter defaults not being set correctly. (@mattdurham)
 
+- Fix agent crash when process null OTel's fan out consumers. (@hainenber)
+
 v0.38.0 (2023-11-21)
 --------------------
 
diff --git a/component/otelcol/internal/fanoutconsumer/logs.go b/component/otelcol/internal/fanoutconsumer/logs.go
index a01202686e01..a8ee4df45b7f 100644
--- a/component/otelcol/internal/fanoutconsumer/logs.go
+++ b/component/otelcol/internal/fanoutconsumer/logs.go
@@ -29,6 +29,10 @@ func Logs(in []otelcol.Consumer) otelconsumer.Logs {
 	for i := 0; i < len(in)-1; i++ {
 		consumer := in[i]
 
+		if consumer == nil {
+			continue
+		}
+
 		if consumer.Capabilities().MutatesData {
 			clone = append(clone, consumer)
 		} else {
@@ -40,10 +44,12 @@ func Logs(in []otelcol.Consumer) otelconsumer.Logs {
 
 	// The final consumer can be given to the passthrough list regardless of
 	// whether it mutates as long as there's no other read-only consumers.
-	if len(passthrough) == 0 || !last.Capabilities().MutatesData {
-		passthrough = append(passthrough, last)
-	} else {
-		clone = append(clone, last)
+	if last != nil {
+		if len(passthrough) == 0 || !last.Capabilities().MutatesData {
+			passthrough = append(passthrough, last)
+		} else {
+			clone = append(clone, last)
+		}
 	}
 
 	return &logsFanout{