From 669a3770ade9e16000ee7658167eccfd791f87b1 Mon Sep 17 00:00:00 2001
From: Hexilee <hexileee@gmail.com>
Date: Fri, 23 Mar 2018 05:05:58 +0800
Subject: [PATCH] Automatically lowercase the index name when custom fields is
 used to build it

---
 libbeat/outputs/elasticsearch/client.go     |  2 +-
 libbeat/outputs/elasticsearch/utils.go      | 18 ++++++++++++++++++
 libbeat/outputs/elasticsearch/utils_test.go | 18 ++++++++++++++++++
 3 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 libbeat/outputs/elasticsearch/utils.go
 create mode 100644 libbeat/outputs/elasticsearch/utils_test.go

diff --git a/libbeat/outputs/elasticsearch/client.go b/libbeat/outputs/elasticsearch/client.go
index 93c3522e74d1..0cec817c3281 100644
--- a/libbeat/outputs/elasticsearch/client.go
+++ b/libbeat/outputs/elasticsearch/client.go
@@ -390,7 +390,7 @@ func createEventBulkMeta(
 	}
 
 	meta := bulkEventMeta{
-		Index:    index,
+		Index:    TryLowercaseIndex(index),
 		DocType:  eventType,
 		Pipeline: pipeline,
 		ID:       id,
diff --git a/libbeat/outputs/elasticsearch/utils.go b/libbeat/outputs/elasticsearch/utils.go
new file mode 100644
index 000000000000..4cc923771c4c
--- /dev/null
+++ b/libbeat/outputs/elasticsearch/utils.go
@@ -0,0 +1,18 @@
+package elasticsearch
+
+import (
+	"unicode"
+	"github.com/elastic/beats/libbeat/logp"
+	"strings"
+)
+
+func TryLowercaseIndex(index string) string {
+	for _, u := range []rune(index) {
+		if unicode.IsUpper(u) {
+			newIndex := strings.ToLower(index)
+			logp.Warn("Index name %s is invalid, replace it with %s", index, newIndex)
+			return newIndex
+		}
+	}
+	return index
+}
diff --git a/libbeat/outputs/elasticsearch/utils_test.go b/libbeat/outputs/elasticsearch/utils_test.go
new file mode 100644
index 000000000000..476d0e731e35
--- /dev/null
+++ b/libbeat/outputs/elasticsearch/utils_test.go
@@ -0,0 +1,18 @@
+package elasticsearch
+
+import (
+	"testing"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestTryLowercaseIndex(t *testing.T) {
+	testCases := map[string]string{
+		"ElasticSearch": "elasticsearch",
+		"ELASTIC":       "elastic",
+		"beats":         "beats",
+	}
+
+	for former, latter := range testCases {
+		assert.Equal(t, latter, TryLowercaseIndex(former))
+	}
+}