The Go implementation of the Couchbase to Elasticsearch with DCP.

  • By Trendyol
  • Last update: Aug 12, 2023
  • Comments: 2

Go Dcp Elasticsearch

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Go implementation of the Elasticsearch Connect Couchbase.

Go Dcp Elasticsearch streams documents from Couchbase Database Change Protocol (DCP) and writes to Elasticsearch index in near real-time.


  • Less resource usage and higher throughput(see Benchmarks).
  • Custom routing support(see Example).
  • Update multiple documents for a DCP event(see Example).
  • Handling different DCP events such as expiration, deletion and mutation(see Example).
  • Elasticsearch compression request body support.
  • 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.


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 Elasticsearch Connect Couchbase used for both connectors.

Package Time to Process Events Elasticsearch Indexing Rate(/s) Average CPU Usage(Core) Average Memory Usage
Go Dcp Elasticsearch(Go 1.20) 50s go 0.486 408MB
Java Elasticsearch Connect Couchbase(JDK15) 80s go 0.31 1091MB


Struct Config

func mapper(event couchbase.Event) []document.ESActionDocument {
	if event.IsMutated {
		e := document.NewIndexAction(event.Key, event.Value, nil)
		return []document.ESActionDocument{e}
	e := document.NewDeleteAction(event.Key, nil)
	return []document.ESActionDocument{e}

func main() {
	connector, err := dcpelasticsearch.NewConnectorBuilder(config.Config{
		Elasticsearch: config.Elasticsearch{
			CollectionIndexMapping: map[string]string{
				"_default": "indexname",
			Urls: []string{"http://localhost:9200"},
		Dcp: dcpConfig.Dcp{
			Username:   "user",
			Password:   "password",
			BucketName: "dcp-test",
			Hosts:      []string{"localhost:8091"},
			Dcp: dcpConfig.ExternalDcp{
				Group: dcpConfig.DCPGroup{
					Name: "groupName",
					Membership: dcpConfig.DCPGroupMembership{
						Type: "static",
			Metadata: dcpConfig.Metadata{
				Config: map[string]string{
					"bucket":     "checkpoint-bucket-name",
					"scope":      "_default",
					"collection": "_default",
				Type: "couchbase",
	if err != nil {

	defer connector.Close()

File Config


Dcp Configuration

Check out on go-dcp

Elasticsearch Specific Configuration

Variable Type Required Default Description
elasticsearch.collectionIndexMapping map[string]string yes Defines which Couchbase collection events will be written to which index
elasticsearch.urls []string yes Elasticsearch connection urls
elasticsearch.typeName string no _doc Defines Elasticsearch index type name
elasticsearch.batchSizeLimit int no 1000 Maximum message count for batch, if exceed flush will be triggered.
elasticsearch.batchTickerDuration time.Duration no 10s Batch is being flushed automatically at specific time intervals for long waiting messages in batch.
elasticsearch.batchByteSizeLimit int no 10485760 Maximum size(byte) for batch, if exceed flush will be triggered.
elasticsearch.maxConnsPerHost int no 512 Maximum number of connections per each host which may be established
elasticsearch.maxIdleConnDuration time.Duration no 10s Idle keep-alive connections are closed after this duration.
elasticsearch.compressionEnabled boolean no false Compression can be used if message size is large, CPU usage may be affected.
elasticsearch.concurrentRequest int no 1 Concurrent bulk request count

Exposed metrics

Metric Name Description Labels Value Type
elasticsearch_connector_latency_ms Time to adding to the batch. N/A Gauge
elasticsearch_connector_bulk_request_process_latency_ms Time to process bulk request. N/A Gauge

For DCP related metrics see also.


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


Released under the MIT License.



  • 1

    discussion: Lets discuss about if actions are nil, we can ack or not?

    actions := c.mapper(e)
    for i := range actions {
        c.bulk.AddAction(ctx, e.EventTime, actions[i], e.CollectionName)

    In this code, we are using ctx.Ack() only actions are not nil. When actions are nil or length zero, we cannot Ack(). Because of this, we are re-processing bad malformed, or invalid documents again, we can change this implementation. Let's discuss

  • 2

    Do not use any config library get Config struct as a parameter

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