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Create a sink connector from Apache Kafka® to Google Pub/Sub

The Google Pub/Sub sink connector enables you to push data from an Aiven for Apache Kafka® topic to a Google Pub/Sub topic.


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


To setup an Google Pub/Sub sink connector, you need an Aiven for Apache Kafka service with Kafka Connect enabled or a dedicated Aiven for Apache Kafka Connect cluster.

Furthermore you need to collect the following information about the target Google Pub/Sub upfront:

  • GCP_PROJECT_NAME: The GCP project name where the target Google Pub/Sub is located

  • GCP_TOPIC: the name of the target Google Pub/Sub topic

  • GCP_SERVICE_KEY: A valid GCP service account key for the GCP_PROJECT_NAME. To create the project key review the dedicated document


    The GCP Pub/Sub sink connector accepts the GCP_SERVICE_KEY JSON service key as a string, therefore all " symbols within it must be escaped \".

    The GCP_SERVICE_KEY parameter should be in the format {\"type\": \"service_account\",\"project_id\": \"XXXXXX\", ...}

    Additionally, any \n symbols contained in the private_key field need to be escaped (by substituting with \\n)

  • KAFKA_TOPIC: The name of the target topic in Aiven for Apache Kafka

  • 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


The SCHEMA_REGISTRY related parameters are available in the Aiven for Apache Kafka® service page, Overview tab, and Schema Registry subtab

As of version 3.0, Aiven for Apache Kafka no longer supports Confluent Schema Registry. For more information, read the article describing the replacement, Karapace

Setup a Google Pub/Sub sink connector with Aiven Console

The following example demonstrates how to setup a Google Pub/Sub sink 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 pubsub_sink.json) with the following content:

"connector.class": "",
"topics": "KAFKA_TOPIC",
"cps.project": "GCP_PROJECT_NAME",
"cps.topic": "GCP_TOPIC",
"gcp.credentials.json": "GCP_SERVICE_KEY",
"key.converter": "io.confluent.connect.avro.AvroConverter",
"key.converter.schema.registry.url": "https://APACHE_KAFKA_HOST:SCHEMA_REGISTRY_PORT",
"key.converter.basic.auth.credentials.sink": "USER_INFO",
"value.converter": "io.confluent.connect.avro.AvroConverter",
"value.converter.schema.registry.url": "https://APACHE_KAFKA_HOST:SCHEMA_REGISTRY_PORT",
"value.converter.basic.auth.credentials.sink": "USER_INFO",

The configuration file contains the following entries:

  • name: the connector name

  • topics: the source Apache Kafka topic names, divided by comma

  • cps.project: the GCP project name where the target Google Pub/Sub is located

  • cps.topic: the name of the target Google Pub/Sub topic

  • gcp.credentials.json: contains the GCP service account key, correctly escaped as defined in the prerequisite phase

  • key.converter and value.converter: define the message data format in the Apache Kafka topic. The io.confluent.connect.avro.AvroConverter converter translates messages from the Avro format. To retrieve the message schema we use Aiven's Karapace schema registry, as specified by the schema.registry.url parameter and related credentials.


    The key.converter and value.converter sections are only needed when the sink data is in Avro format. If omitted the messages will be read as binary format.

    When using Avro as sink data format, you need to set following parameters

    • value.converter.schema.registry.url: pointing to the Aiven for Apache Kafka schema registry URL in the form of https://APACHE_KAFKA_HOST:SCHEMA_REGISTRY_PORT with the APACHE_KAFKA_HOST and SCHEMA_REGISTRY_PORT parameters retrieved in the previous step.
    • value.converter.basic.auth.credentials.sink: to the value USER_INFO, since you're going to login to the schema registry using username and password.
    • passing the required schema registry credentials in the form of SCHEMA_REGISTRY_USER:SCHEMA_REGISTRY_PASSWORD with the SCHEMA_REGISTRY_USER and SCHEMA_REGISTRY_PASSWORD parameters retrieved in the previous step.

The full list of parameters is available in the dedicated GitHub page.

Create a Kafka Connect connector with the Aiven Console

To create an Apache Kafka Connect connector, follow these steps:

  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, the button is enabled only for services with Kafka Connect enabled.

  4. Select Google Pub/Sub sink.

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

  6. Paste the connector configuration (stored in the pubsub_sink.json file) in the form.

  7. Select Apply.


    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.

  9. Verify the connector status under the Connectors screen.

  10. Verify the presence of the data in the target Pub/Sub dataset, the table name is equal to the Apache Kafka topic name.


    You can also create connectors using the Aiven CLI command.

Example: Create a Google Pub/Sub sink connector

You have an Apache Kafka topic iot_metrics that you want to push to a Google Pub/Sub topic iot_metrics_pubsub, you can create a sink connector with the following configuration, after replacing the placeholders for GCP_PROJECT_NAME and GCP_SERVICE_KEY:

"connector.class": "",
"topics": "iot_metrics",
"cps.project": "GCP_PROJECT_NAME",
"cps.topic": "iot_metrics_pubsub",
"gcp.credentials.json": "GCP_SERVICE_KEY"