MQTT Sink Connector for Confluent Platform¶

The Kafka Connect MQTT connector is used to integrate with existing MQTT servers. The connector is compatible with Confluent Platform, version 4.1 and later. Prior versions do not work with this connector. The Kafka Connect MQTT Sink Connector connects to an MQTT broker and publishes data to an MQTT topic. SSL is supported. For information on how to create SSL keys and certificates see Creating SSL Keys and Certificates. For the relevant configuration properties, see the MQTT Sink Connector Configuration Properties.

At least once delivery¶

This connector guarantees that records are delivered at least once from the Kafka topic.

Dead Letter Queue¶

This connector supports the Dead Letter Queue (DLQ) functionality. For information about accessing and using the DLQ, see Confluent Platform Dead Letter Queue.

Multiple tasks¶

The MQTT Sink Connector supports running one or more tasks. You can specify the number of tasks in the tasks.max configuration parameter. This can lead to huge performance gains when multiple files need to be parsed.

Schemas¶

The connector supports Avro, JSON Schema, and Protobuf input data formats. Schema Registry must be enabled to use a Schema Registry-based format. Note that the connector only supports bytes and string schemas. It does not support structs. If you want to have struct type schemas, you can store the struct data as bytes and select bytes in the connector.

License¶

You can use this connector for a 30-day trial period without a license key.

After 30 days, you must purchase a connector subscription which includes Confluent enterprise license keys to subscribers, along with enterprise-level support for Confluent Platform and your connectors. If you are a subscriber, you can contact Confluent Support at support@confluent.io for more information.

For license properties, see Confluent Platform license and License topic configuration, and for information about the license topic, see License topic configuration .

Configuration properties¶

For a complete list of configuration properties for this connector, see MQTT Sink Connector Configuration Properties.

For an example of how to get Kafka Connect connected to Confluent Cloud, see Connect Self-Managed Kafka Connect to Confluent Cloud.

Connection validation and client IDs¶

The MQTT Sink connector validates connection using a randomly generated client ID. This validation method is fine in most cases, however, issues may arise if the MQTT broker rejects clients based on client IDs.

Once validated, if mqtt.clean.session.enabled is set to false, the connector generates a client ID in the format <connnector-name>-<task-id>. For example, if a connector with the name “mymqtt” has 3 tasks, the following client IDs are generated: “mymqtt-0”, “mymqtt-1”, and “mymqtt-2”. If you set mqtt.clean.session.enabled to true, the connector uses a randomly generated client ID.

Install the MQTT Sink connector¶

You can install this connector by using the confluent connect plugin install command, or by manually downloading the ZIP file.

Prerequisites¶

You must install the connector on every machine where Connect will run.
If you want to install the connector using Confluent Hub, you must install the Confluent Hub Client. This is installed by default with Confluent Enterprise.

Install the connector using the Confluent CLI¶

To install the latest connector version using Confluent Hub Client, navigate to your Confluent Platform installation directory and run the following command:

confluent connect plugin install confluentinc/kafka-connect-mqtt:latest

You can install a specific version by replacing latest with a version number as shown in the following example:

confluent connect plugin install confluentinc/kafka-connect-mqtt:1.7.0

Install the connector manually¶

Download and extract the ZIP file for your connector and then follow the manual connector installation instructions.

Usage notes¶

If you want to change the topic take a look at the RegexRouter transformation which can be used to change the topic name it is sent to the MQTT Server.

This connector publishes using the Apache Kafka® topic name. If you need to publish to a different topic name use a transformation to change the topic name.

Examples¶

Property-based example¶

This configuration is used typically along with standalone workers.

 name=MqttSinkConnector1
 connector.class=io.confluent.connect.mqtt.MqttSinkConnector
 tasks.max=1
 topics=< Required Configuration >
 mqtt.server.uri=< Required Configuration >

REST-based example¶

This configuration is used typically along with distributed workers. Write the following json to connector.json, configure all of the required values, and use the command below to post the configuration to one the distributed connect worker(s). Check here for more information about the Kafka Connect REST API

Connect Distributed REST example:

 {
   "config" : {
     "name" : "MqttSinkConnector1",
     "connector.class" : "io.confluent.connect.mqtt.MqttSinkConnector",
     "tasks.max" : "1",
     "topics" : "< Required Configuration >",
     "mqtt.server.uri" : "< Required Configuration >"
   }
 }

Use curl to post the configuration to one of the Kafka Connect Workers. Change http://localhost:8083/ the endpoint of one of your Kafka Connect worker(s).

Create a new connector:

curl -s -X POST -H 'Content-Type: application/json' --data @connector.json http://localhost:8083/connectors

Update an existing connector:

curl -s -X PUT -H 'Content-Type: application/json' --data @connector.json http://localhost:8083/connectors/MqttSinkConnector1/config