feat(inputs.kafka_consumer): Add message headers as metric tags.

plugins/inputs/kafka_consumer/README.md

@@ -43,6 +43,16 @@ to use them.
   ## Kafka brokers.
   brokers = ["localhost:9092"]
 
+  ## Set the minimal supported Kafka version. Should be a string contains 
+  ## 4 digits in case if it is 0 version and 3 digits for versions starting
+  ## from 1.0.0 separated by dot. This setting enables the use of new
+  ## Kafka features and APIs.  Must be 0.10.2.0(used as default) or greater.
+  ## Please, check the list of supported versions at 
+  ## https://pkg.go.dev/github.com/Shopify/sarama#SupportedVersions
+  ##   ex: kafka_version = "2.6.0"
+  ##   ex: kafka_version = "0.10.2.0"
+  # kafka_version = "0.10.2.0"
+
   ## Topics to consume.
   topics = ["telegraf"]
 
@@ -53,14 +63,14 @@ to use them.
   ## When set this tag will be added to all metrics with the topic as the value.
   # topic_tag = ""
 
+  ## The list of Kafka message headers that should be pass as metric tags
+  ## works only for Kafka version 0.11+, on lower versions the message headers 
+  ## are not available
+  # msg_headers_to_tags = []
+
   ## Optional Client id
   # client_id = "Telegraf"
 
-  ## Set the minimal supported Kafka version.  Setting this enables the use of new
-  ## Kafka features and APIs.  Must be 0.10.2.0 or greater.
-  ##   ex: version = "1.1.0"
-  # version = ""
-
   ## Optional TLS Config
   # enable_tls = false
   # tls_ca = "/etc/telegraf/ca.pem"

plugins/inputs/kafka_consumer/kafka_consumer.go

@@ -35,6 +35,7 @@ type semaphore chan empty
 
 type KafkaConsumer struct {
 	Brokers                []string        `toml:"brokers"`
+	Version                string          `toml:"kafka_version"`
 	ConsumerGroup          string          `toml:"consumer_group"`
 	MaxMessageLen          int             `toml:"max_message_len"`
 	MaxUndeliveredMessages int             `toml:"max_undelivered_messages"`
@@ -44,6 +45,7 @@ type KafkaConsumer struct {
 	Topics                 []string        `toml:"topics"`
 	TopicRegexps           []string        `toml:"topic_regexps"`
 	TopicTag               string          `toml:"topic_tag"`
+	MsgHeadersAsTags       []string        `toml:"msg_headers_as_tags"`
 	ConsumerFetchDefault   config.Size     `toml:"consumer_fetch_default"`
 	ConnectionStrategy     string          `toml:"connection_strategy"`
 
@@ -109,7 +111,15 @@ func (k *KafkaConsumer) Init() error {
 	cfg := sarama.NewConfig()
 
 	// Kafka version 0.10.2.0 is required for consumer groups.
+	// Try to parse version from config. If can not, set default
 	cfg.Version = sarama.V0_10_2_0
+	if k.Version != "" {
+		version, err := sarama.ParseKafkaVersion(k.Version)
+		if err != nil {
+			return fmt.Errorf("invalid version: %w", err)
+		}
+		cfg.Version = version
+	}
 
 	if err := k.SetConfig(cfg, k.Log); err != nil {
 		return fmt.Errorf("SetConfig: %w", err)
@@ -311,6 +321,15 @@ func (k *KafkaConsumer) Start(acc telegraf.Accumulator) error {
 			handler := NewConsumerGroupHandler(acc, k.MaxUndeliveredMessages, k.parserFunc, k.Log)
 			handler.MaxMessageLen = k.MaxMessageLen
 			handler.TopicTag = k.TopicTag
+			//if message headers list specified, put it as map to handler
+			msgHeadersMap := make(map[string]bool, len(k.MsgHeadersAsTags))
+			if len(k.MsgHeadersAsTags) > 0 {
+				for _, header := range k.MsgHeadersAsTags {
+					msgHeadersMap[header] = true
+				}
+			}
+			handler.MsgHeadersToTags = msgHeadersMap
+
 			// We need to copy allWantedTopics; the Consume() is
 			// long-running and we can easily deadlock if our
 			// topic-update-checker fires.
@@ -371,8 +390,9 @@ func NewConsumerGroupHandler(acc telegraf.Accumulator, maxUndelivered int, fn te
 
 // ConsumerGroupHandler is a sarama.ConsumerGroupHandler implementation.
 type ConsumerGroupHandler struct {
-	MaxMessageLen int
-	TopicTag      string
+	MaxMessageLen    int
+	TopicTag         string
+	MsgHeadersToTags map[string]bool
 
 	acc        telegraf.TrackingAccumulator
 	sem        semaphore
@@ -467,6 +487,22 @@ func (h *ConsumerGroupHandler) Handle(session sarama.ConsumerGroupSession, msg *
 		return err
 	}
 
+	// Check if any message header should be pass as tag
+	header_key := ""
+	if len(h.MsgHeadersToTags) > 0 {
+		for _, header := range msg.Headers {
+			//convert to a string as the header and value are byte arrays.
+			header_key = string(header.Key)
+			if _, exists := h.MsgHeadersToTags[header_key]; exists {
+				// If message header should be pass as tag then add it to the metrics
+				for _, metric := range metrics {
+					metric.AddTag(header_key, string(header.Value))
+				}
+			}
+		}
+	}
+
+	// Add topic name as tag with TopicTag name specified in the config
 	if len(h.TopicTag) > 0 {
 		for _, metric := range metrics {
 			metric.AddTag(h.TopicTag, msg.Topic)

plugins/inputs/kafka_consumer/sample.conf

@@ -3,6 +3,16 @@
   ## Kafka brokers.
   brokers = ["localhost:9092"]
 
+  ## Set the minimal supported Kafka version. Should be a string contains 
+  ## 4 digits in case if it is 0 version and 3 digits for versions starting
+  ## from 1.0.0 separated by dot. This setting enables the use of new
+  ## Kafka features and APIs.  Must be 0.10.2.0(used as default) or greater.
+  ## Please, check the list of supported versions at 
+  ## https://pkg.go.dev/github.com/Shopify/sarama#SupportedVersions
+  ##   ex: kafka_version = "2.6.0"
+  ##   ex: kafka_version = "0.10.2.0"
+  # kafka_version = "0.10.2.0"
+
   ## Topics to consume.
   topics = ["telegraf"]
 
@@ -13,14 +23,14 @@
   ## When set this tag will be added to all metrics with the topic as the value.
   # topic_tag = ""
 
+  ## The list of Kafka message headers that should be pass as metric tags
+  ## works only for Kafka version 0.11+, on lower versions the message headers 
+  ## are not available
+  # msg_headers_to_tags = []
+
   ## Optional Client id
   # client_id = "Telegraf"
 
-  ## Set the minimal supported Kafka version.  Setting this enables the use of new
-  ## Kafka features and APIs.  Must be 0.10.2.0 or greater.
-  ##   ex: version = "1.1.0"
-  # version = ""
-
   ## Optional TLS Config
   # enable_tls = false
   # tls_ca = "/etc/telegraf/ca.pem"