MQTT Source 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 Source Connector connects to a MQTT broker and subscribes to the specified topics. 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 Source Connector configuration reference.

At least once delivery¶

For at-least-once semantics, some restrictions apply. To support this feature, you must run the connector with mqtt.clean.session.enabled set to false. Under this mode, the connector will assign each task a unique client ID, which will be used for a persistent connection.

The topics are distributed across tasks. Confluent recommends you do not change the topic assignments–that is, do not alter the task count, or change the topic listing once the connector is up and running. This can potentially lead to data loss as the connector will be restarted with a different topic to task assignments, and hence, a different client ID.

Multiple tasks¶

The MQTT Source 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.

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 source connector, see MQTT Source Connector Configuration Properties.

Note

For an example of how to get Kafka Connect connected to Confluent Cloud, see Distributed Cluster.

Install the MQTT Source Connector¶

You can install this connector by using the Confluent Hub client installation instructions 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 Confluent Hub¶

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

confluent-hub 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-hub 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 need to change the topic take a look at the RegexRouter transformation which can be used to change the topic name before it is written to Apache Kafka®.

The output of this connector is an envelope with all of the properties of the incoming message. The body of the message is written to the value as bytes. The key is the topic the message was written to.

Examples¶

Property-based example¶

This configuration is used typically along with standalone workers.

 name=MqttSourceConnector1
 connector.class=io.confluent.connect.mqtt.MqttSourceConnector
 tasks.max=1
 mqtt.server.uri=< Required Configuration >
 mqtt.topics=< 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" : "MqttSourceConnector1",
     "connector.class" : "io.confluent.connect.mqtt.MqttSourceConnector",
     "tasks.max" : "1",
     "mqtt.server.uri" : "< Required Configuration >",
     "mqtt.topics" : "< 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/MqttSourceConnector1/config