Add support for setting kafka client id (#4418)

plugins/outputs/kafka/README.md

@@ -10,6 +10,9 @@ This plugin writes to a [Kafka Broker](http://kafka.apache.org/07/quickstart.htm
   ## Kafka topic for producer messages
   topic = "telegraf"
 
+  ## Optional client id
+  # client_id = "my_client"
+
   ## Optional topic suffix configuration.
   ## If the section is omitted, no suffix is used.
   ## Following topic suffix methods are supported:

plugins/outputs/kafka/kafka.go

@@ -25,6 +25,8 @@ type (
 		Brokers []string
 		// Kafka topic
 		Topic string
+		// Kafka client id
+		ClientID string `toml:"client_id"`
 		// Kafka topic suffix option
 		TopicSuffix TopicSuffix `toml:"topic_suffix"`
 		// Routing Key Tag
@@ -68,6 +70,9 @@ var sampleConfig = `
   brokers = ["localhost:9092"]
   ## Kafka topic for producer messages
   topic = "telegraf"
+  
+  ## Optional Client id
+  # client_id = "Telegraf"
 
   ## Optional topic suffix configuration.
   ## If the section is omitted, no suffix is used.
@@ -186,6 +191,12 @@ func (k *Kafka) Connect() error {
 	}
 	config := sarama.NewConfig()
 
+	if k.ClientID != "" {
+		config.ClientID = k.ClientID
+	} else {
+		config.ClientID = "Telegraf"
+	}
+
 	config.Producer.RequiredAcks = sarama.RequiredAcks(k.RequiredAcks)
 	config.Producer.Compression = sarama.CompressionCodec(k.CompressionCodec)
 	config.Producer.Retry.Max = k.MaxRetry