README.md

Go Dcp Kafka

Go implementation of the Kafka Connect Couchbase.

Go Dcp Kafka streams documents from Couchbase Database Change Protocol (DCP) and publishes Kafka events in near real-time.

Features

• Less resource usage and higher throughput(see Benchmarks).
• Custom Kafka key and headers implementation(see Example).
• Sending multiple Kafka events for a DCP event(see Example).
• Handling different DCP events such as expiration, deletion and mutation(see Example).
• Kafka compression support(Gzip, Snappy, Lz4, Zstd).
• Kafka producer acknowledges support(fire-and-forget, wait for the leader, wait for the full ISR).
• Metadata can be saved to Couchbase or Kafka.
• Managing batch configurations such as maximum batch size, batch bytes, batch ticker durations.
• Scale up and down by custom membership algorithms(Couchbase, KubernetesHa, Kubernetes StatefulSet or Static, see examples).
• Easily manageable configurations.

Benchmarks

The benchmark was made with the 1,001,006 Couchbase document, because it is possible to more clearly observe the difference in the batch structure between the two packages. Default configurations for Java Kafka Connect Couchbase used for both connectors.

Package	Time to Process Events	Average CPU Usage(Core)	Average Memory Usage
Go Dcp Kafka(1.20)	12s	0.383	428MB
Java Kafka Connect Couchbase(JDK11)	19s	1.5	932MB

Example

Struct Config

func mapper(event couchbase.Event) []message.KafkaMessage {
	// return nil if you wish to discard the event
	return []message.KafkaMessage{
		{
			Headers: nil,
			Key:     event.Key,
			Value:   event.Value,
		},
	}
}

func main() {
	c, err := dcpkafka.NewConnector(&config.Connector{
		Dcp: dcpConfig.Dcp{
			Hosts:      []string{"localhost:8091"},
			Username:   "user",
			Password:   "password",
			BucketName: "dcp-test",
			Dcp: dcpConfig.ExternalDcp{
				Group: dcpConfig.DCPGroup{
					Name: "groupName",
					Membership: dcpConfig.DCPGroupMembership{
						RebalanceDelay: 3 * time.Second,
					},
				},
			},
			Metadata: dcpConfig.Metadata{
				Config: map[string]string{
					"bucket":     "checkpoint-bucket-name",
					"scope":      "_default",
					"collection": "_default",
				},
				Type: "couchbase",
			},
			Debug: true},
		Kafka: config.Kafka{
			CollectionTopicMapping: map[string]string{"_default": "topic"},
			Brokers:                []string{"localhost:9092"},
		},
	}, mapper)
	if err != nil {
		panic(err)
	}

	defer c.Close()
	c.Start()
}

File Config

File Config

Configuration

Dcp Configuration

Check out on go-dcp

Kafka Specific Configuration

Variable	Type	Required	Default	Description
kafka.collectionTopicMapping	map[string]string	yes		Defines which Couchbase collection events will be sent to which topic,:warning: If topic information is entered in the mapper, it will OVERWRITE this config.
kafka.brokers	[]string	yes		Broker ip and port information
kafka.producerBatchSize	integer	no	2000	Maximum message count for batch, if exceed flush will be triggered.
kafka.producerBatchBytes	64 bit integer	no	1mb	Maximum size(byte) for batch, if exceed flush will be triggered. 1mb is default.
kafka.producerMaxAttempts	int	no	math.MaxInt	Limit on how many attempts will be made to deliver a message.
kafka.producerBatchTickerDuration	time.Duration	no	10s	Batch is being flushed automatically at specific time intervals for long waiting messages in batch.
kafka.readTimeout	time.Duration	no	30s	segmentio/kafka-go - Timeout for read operations
kafka.writeTimeout	time.Duration	no	30s	segmentio/kafka-go - Timeout for write operations
kafka.compression	integer	no	0	Compression can be used if message size is large, CPU usage may be affected. 0=None, 1=Gzip, 2=Snappy, 3=Lz4, 4=Zstd
kafka.balancer	string	no	Hash	Define balancer strategy. Available fields: Hash, LeastBytes, RoundRobin, ReferenceHash, CRC32Balancer, Murmur2Balancer.
kafka.requiredAcks	integer	no	1	segmentio/kafka-go - Number of acknowledges from partition replicas required before receiving a response to a produce request. 0=fire-and-forget, do not wait for acknowledgements from the, 1=wait for the leader to acknowledge the writes, -1=wait for the full ISR to acknowledge the writes
kafka.secureConnection	bool	no	false	Enable secure Kafka.
kafka.rootCAPath	string	no	*not set	Define root CA path.
kafka.interCAPath	string	no	*not set	Define inter CA path.
kafka.scramUsername	string	no	*not set	Define scram username.
kafka.scramPassword	string	no	*not set	Define scram password.
kafka.metadataTTL	time.Duration	no	60s	TTL for the metadata cached by segmentio, increase it to reduce network requests. For more detail please check docs.
kafka.metadataTopics	[]string	no		Topic names for the metadata cached by segmentio, define topics here that the connector may produce. In large Kafka clusters, this will reduce memory usage. For more detail please check docs.
kafka.clientID	string	no		Unique identifier that the transport communicates to the brokers when it sends requests. For more detail please check docs.
kafka.allowAutoTopicCreation	bool	no	false	Create topic if missing. For more detail please check docs.

Kafka Metadata Configuration(Use it if you want to store the checkpoint data in Kafka)

Variable	Type	Description
metadata.type	string	Metadata storing types. kafka,file or couchbase.
metadata.readOnly	bool	Set this for debugging state purposes.
metadata.config	map[string]string	Set key-values of config. topic,partition,replicationFactor for kafka type

Exposed metrics

Metric Name	Description	Labels	Value Type
cbgo_kafka_connector_latency_ms_current	Time to adding to the batch.	N/A	Gauge
cbgo_kafka_connector_batch_produce_latency_ms_current	Time to produce messages in the batch.	N/A	Gauge

You can also use all DCP-related metrics explained here. All DCP-related metrics are automatically injected. It means you don't need to do anything.

Breaking Changes

Date taking effect	Date announced	Change	How to check
November 11, 2023	November 11, 2023	Creating connector via builder	Compile project

Grafana Metric Dashboard

Grafana & Prometheus Example

Contributing

Go Dcp Kafka is always open for direct contributions. For more information please check our Contribution Guideline document.

License

Released under the MIT License.