From fe7ab2f2cebd2e0a6d4f82f055717c0ec0841a3b Mon Sep 17 00:00:00 2001
From: jeffail <ash@jeffs.eu>
Date: Wed, 17 Jan 2018 16:10:15 +0000
Subject: [PATCH] Avoid brokers when unnecessary

---
 lib/input/fan_in.go       | 6 ++++++
 lib/output/fan_out.go     | 6 ++++++
 lib/output/round_robin.go | 6 ++++++
 3 files changed, 18 insertions(+)

diff --git a/lib/input/fan_in.go b/lib/input/fan_in.go
index 2a50b593e9..e8a79ae725 100644
--- a/lib/input/fan_in.go
+++ b/lib/input/fan_in.go
@@ -238,6 +238,12 @@ func NewFanIn(
 		return nil, err
 	}
 
+	if len(inputConfs) == 0 {
+		return nil, ErrFanInNoInputs
+	} else if len(inputConfs) == 1 {
+		return New(inputConfs[0], log, stats, pipelines...)
+	}
+
 	inputs := make([]types.Producer, len(inputConfs))
 
 	for i, iConf := range inputConfs {
diff --git a/lib/output/fan_out.go b/lib/output/fan_out.go
index 496e9dcd17..177fcf1127 100644
--- a/lib/output/fan_out.go
+++ b/lib/output/fan_out.go
@@ -85,6 +85,12 @@ func NewFanOut(conf Config, log log.Modular, stats metrics.Type) (Type, error) {
 		return nil, err
 	}
 
+	if len(outputConfs) == 0 {
+		return nil, ErrFanOutNoOutputs
+	} else if len(outputConfs) == 1 {
+		return New(outputConfs[0], log, stats)
+	}
+
 	outputs := make([]types.Consumer, len(outputConfs))
 
 	for i, oConf := range outputConfs {
diff --git a/lib/output/round_robin.go b/lib/output/round_robin.go
index ba57e14882..e1f560174e 100644
--- a/lib/output/round_robin.go
+++ b/lib/output/round_robin.go
@@ -80,6 +80,12 @@ func NewRoundRobin(conf Config, log log.Modular, stats metrics.Type) (Type, erro
 		return nil, err
 	}
 
+	if len(outputConfs) == 0 {
+		return nil, ErrFanOutNoOutputs
+	} else if len(outputConfs) == 1 {
+		return New(outputConfs[0], log, stats)
+	}
+
 	outputs := make([]types.Consumer, len(outputConfs))
 
 	for i, oConf := range outputConfs {