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Create a source connector from Couchbase to Apache Kafka®

The Couchbase source connector pushes data from the NoSQL database, to Apache Kafka® where it can be transformed and read by multiple consumers.

tip

Sourcing data from a database into Apache Kafka decouples the database from the set of consumers. Once the data is in Apache Kafka, multiple applications can access it without adding any additional query overhead to the source database.

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See the full set of available parameters and configuration options in the connector's documentation.

Prerequisites​

To setup a Couchbase source connector, you need an Aiven for Apache Kafka service with Kafka Connect enabled or a dedicated Aiven for Apache Kafka Connect cluster.

Also collect the following information about the source Couchbase database upfront:

  • COUCHBASE_SEED_NODES: The database seed nodes
  • COUCHBASE_USER: The database user to connect
  • COUCHBASE_PASSWORD: The database password for the COUCHBASE_USER
  • COUCHBASE_BUCKET: The bucket from which extract the data
  • COUCHBASE_SCOPE: The scope from which extract the data (if none all the scopes within the bucket will be sourced)
  • COUCHBASE_COLLECTIONS: The list of collections from which extract the data (if none all the collections within the bucket and scope will be sourced)
  • APACHE_KAFKA_HOST: The hostname of the Apache Kafka service, only needed when using Avro as data format
  • SCHEMA_REGISTRY_PORT: The Apache Kafka's schema registry port, only needed when using Avro as data format
  • SCHEMA_REGISTRY_USER: The Apache Kafka's schema registry username, only needed when using Avro as data format
  • SCHEMA_REGISTRY_PASSWORD: The Apache Kafka's schema registry user password, only needed when using Avro as data format
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If you're using Aiven for Apache Kafka®, the Kafka related details are available in the Aiven console service Overview tab or via the dedicated avn service get command with the Aiven CLI.

Setup a Couchbase source connector with Aiven Console​

The following example demonstrates how to setup a Couchbase source connector for Apache Kafka using the Aiven Console.

Define a Kafka Connect configuration file​

Define the connector configurations in a file (we'll refer to it with the name couchbase-source.json) with the following content. Creating a file is not strictly necessary but allows to have all the information in one place before copy/pasting them in the Aiven Console:

{
    "name":"CONNECTOR_NAME",
    "connector.class": "com.couchbase.connect.kafka.CouchbaseSourceConnector",
    "couchbase.seed.nodes": "COUCHBASE_SEED_NODES",
    "couchbase.username": "COUCHBASE_USER",
    "couchbase.password": "COUCHBASE_PASSWORD",
    "couchbase.bucket": "COUCHBASE_BUCKET",
    "couchbase.scope": "COUCHBASE_SCOPE",
    "couchbase.collections": "COUCHBASE_COLLECTIONS",
    "couchbase.source.handler": "com.couchbase.connect.kafka.handler.source.RawJsonSourceHandler",
    "value.converter": "org.apache.kafka.connect.converters.ByteArrayConverter",
}

The configuration file contains the following entries:

  • name: the connector name, replace CONNECTOR_NAME with the name you want to use for the connector
  • COUCHBASE_SEED_NODES, COUCHBASE_BUCKET, COUCHBASE_SCOPE, COUCHBASE_COLLECTIONS, COUCHBASE_USER, COUCHBASE_PASSWORD: source database parameters collected in the prerequisite phase.
  • couchbase.source.handler and value.converter: defines the messages data format in the Apache Kafka topic. The combination of com.couchbase.connect.kafka.handler.source.RawJsonSourceHandler and org.apache.kafka.connect.converters.ByteArrayConverter pushes the Couchbase documents in the Kafka topic in JSON format.

Create a Kafka Connect connector with the Aiven Console​

To create a Kafka Connect connector:

  1. Log in to the Aiven Console and select the Aiven for Apache Kafka® or Aiven for Apache Kafka Connect® service where the connector needs to be defined.

  2. Select Connectors from the left sidebar.

  3. Select Create New Connector, it is enabled only for services with Kafka Connect enabled.

  4. Select Couchbase Source.

  5. In the Common tab, locate the Connector configuration text box and select on Edit.

  6. Paste the connector configuration (stored in the couchbase-source.json file) in the form.

  7. Select Apply.

    note

    The Aiven Console parses the configuration file and fills the relevant UI fields. You can review the UI fields across the various tabs and change them if necessary. The changes will be reflected in JSON format in the Connector configuration text box.

  8. After all the settings are correctly configured, select Create connector.

    tip

    If you're using Aiven for Apache Kafka, topics will not be created automatically. Either create them manually following the database.server.name.schema_name.table_name naming pattern or enable the kafka.auto_create_topics_enable advanced parameter.

  9. Verify the connector status under the Connectors tab

  10. Verify the presence of the data in the target Apache Kafka topic coming from the MongoDB dataset. The topic name is equal to the concatenation of the database and collection name. To change the target table name, you can do so using the Kafka Connect RegexRouter transformation.

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You can also create connectors using the Aiven CLI command.

Example: define a Couchbase source connector​

The example creates an Couchbase source connector with the following properties:

  • connector name: couchbase_source
  • Couchbase seeds: test.cloud.couchbase.com
  • Couchbase username: testuser
  • Couchbase password: Test123!
  • Couchbase bucket: travel-sample
  • Couchbase scope: inventory
  • Couchbase collections: airline

The connector configuration is the following:

{
    "name": "couchbase_source",
    "connector.class": "com.couchbase.connect.kafka.CouchbaseSourceConnector",
    "couchbase.seed.nodes": "test.cloud.couchbase.com",
    "couchbase.username": "testuser",
    "couchbase.password": "Test123!",
    "couchbase.bucket": "travel-sample",
    "couchbase.scope": "inventory",
    "couchbase.collections": "airline",
    "couchbase.source.handler": "com.couchbase.connect.kafka.handler.source.RawJsonSourceHandler",
    "value.converter": "org.apache.kafka.connect.converters.ByteArrayConverter"
}

With the above configuration stored in a couchbase-source.json file, you can create the connector in the demo-kafka instance and you should see the data landing in an Apache Kafka topic named ${bucket}.${scope}.${collection} by default, you can change the landing topic logic by modifying the couchbase.topic parameter definition.

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