<a id="mqtt-sink-connector"></a>

# 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](/platform/current/security/security_tutorial.html#creating-ssl-keys-and-certificates).
For the relevant configuration properties, see the
[Configuration Reference for MQTT Sink Connector for Confluent Platform](mqtt_sink_connector_config.md#mqtt-sink-connector-config).

#### IMPORTANT
<!-- WARNING: THIS IS A SHARED FILE AND THE SOURCE IS LOCATED IN DOCS-COMMON. DO NOT ADD TO ANY OTHER REPO. -->

Effective July 6, 2025, only self-managed connector versions that meet or exceed the minimum version listed on the
[Supported Connector Versions](https://docs.confluent.io/platform/7.8/connect/supported-connector-version.html#supported-connector-versions-till-cp-7-8)
page receive support from Confluent. Older, unsupported connector versions have been removed from Confluent Marketplace and
are no longer available for download.

## Features

- [At least once delivery](#mqtt-sink-at-least-once-delivery)
- [Dead Letter Queue](#mqtt-sink-dead-letter-queue)
- [Multiple tasks](#mqtt-sink-multiple-tasks)
- [Schemas](#mqtt-sink-schemas)

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### At least once delivery

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

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### 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](/platform/current/connect/concepts.html#dead-letter-queue).

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### 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.

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### Schemas

The connector supports Avro, JSON Schema, and Protobuf input data formats.
[Schema Registry](/platform/current/schema-registry/connect.html) 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](/platform/current/installation/license.html#enterprise-subscription-license) keys to subscribers, along with [enterprise-level support](https://www.confluent.io/subscription/) for Confluent Platform and your connectors. If you are a subscriber, you can contact [Confluent Support](https://support.confluent.io/) for more information.

For license properties, see [Confluent Platform license](../mqtt-source-connector/mqtt_source_connector_config.md#mqtt-source-connector-license-config)  and
[License topic configuration](mqtt_sink_connector_config.md#mqtt-sink-license-topic-configuration), and for information about the
license topic, see [License topic configuration](../mqtt-source-connector/mqtt_source_connector_config.md#mqtt-source-license-topic-configuration) .

## Configuration properties

For a complete list of configuration properties for this connector, see
[Configuration Reference for MQTT Sink Connector for Confluent Platform](mqtt_sink_connector_config.md#mqtt-sink-connector-config).

For an example of how to get Kafka Connect connected to [Confluent Cloud](/cloud/current/index.html), see
[Connect Self-Managed Kafka Connect to Confluent Cloud](/cloud/current/cp-component/connect-cloud-config.html#distributed-cluster).

## 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](https://docs.confluent.io/confluent-cli/current/command-reference/connect/plugin/confluent_connect_plugin_install.html)
command, or by manually downloading the ZIP file.

### Prerequisites

- You must install the connector on every machine where Connect will run.
- Java 8+. Note that Java 8 is deprecated in versions 7.2 and later of Confluent Platform. For
  more details, view [Java compatibility with Confluent Platform](/platform/current/installation/versions-interoperability.html#java)
   by version.
- [Confluent CLI](https://docs.confluent.io/confluent-cli/current/installing.html)
- An installation of the latest (`latest`) connector version.

### Install the connector using the Confluent CLI

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

```bash
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:

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

### Install the connector manually

[Download and extract the ZIP file](https://www.confluent.io/hub/confluentinc/kafka-connect-mqtt) for your
connector and then follow the manual connector installation
[instructions](/kafka-connectors/self-managed/userguide.html#connect-installing-plugins).

## Usage notes

If you want to change the topic take a look at the
[RegexRouter](/platform/current/connect/transforms/regexrouter.html) 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.

## Quick start

The MQTT Sink connector is used to publish records in an Apache Kafka® topic to MQTT
brokers. This quick start demonstrates how to configure an MQTT Sink connector for
the Eclipse Mosquitto broker.

### Set up Mosquitto broker and clients

In this step, an Eclipse Mosquitto broker is set up by using Docker images.

1. Install the Mosquitto [utilities](https://mosquitto.org/download/) for your operating system.
2. Create a config file named `mosquitto.conf` for the broker with the following contents.
   ```properties
   persistence false
   log_dest stdout
   allow_anonymous true
   connection_messages true
   ```
3. Start the Docker container.
   ```bash
   docker run --name mosquitto -p 1881:1881 -v `pwd`/mosquitto.conf:/mosquitto/config/mosquitto.conf eclipse-mosquitto
   ```
4. Start the Docker container using this command.
   ```bash
   docker run --name mosquitto -p 1881:1881 -v `pwd`/mosquitto.conf:/mosquitto/config/mosquitto.conf -v `pwd`/password:/etc/mosquitto/passwd eclipse-mosquitto
   ```
5. Verify that the broker is running by publishing a message to it.
   ```bash
   mosquitto_pub -h localhost -p 1881 -t my-mqtt-topic -m "sample-msg-1"
   ```
6. To subscribe to all messages on a Mosquitto topic, use the `mosquitto_sub` command.
   ```bash
   mosquitto_sub -h localhost -p 1881 -t my-mqtt-topic
   ```

## Install the MQTT Connector Plugin

1. Navigate to your Confluent Platform installation directory and run this command to install the latest version of the MQTT connector.
   ```bash
   confluent connect plugin install confluentinc/kafka-connect-mqtt:latest
   ```
2. Restart Connect to pick up the new plugin.
   ```bash
   confluent local services connect stop && confluent local services connect start
   ```
3. Check if the MQTT plugin has been installed correctly and picked up by the plugin loader:
   ```bash
   curl -sS localhost:8083/connector-plugins | jq -c '.[] | select( .class | contains("Mqtt") )'
   ```

   This command should print the new MQTT connector plugins available to the worker.
   ```bash
   {"class": "io.confluent.connect.mqtt.MqttSinkConnector","type": "sink","version": "1.1.0-preview"}
   {"class": "io.confluent.connect.mqtt.MqttSourceConnector","type": "source","version": "1.1.0-preview"}
   ```

### Configure the connector

1. Create a configuration file named `mqtt-sink-config.json` with the following contents.
   ```bash
   {
       "name": "mqtt-sink",
       "config": {
           "connector.class": "io.confluent.connect.mqtt.MqttSinkConnector",
           "tasks.max": "1",
           "mqtt.server.uri": "tcp://127.0.0.1:1881",
           "topics":"kafka-topic-name",
           "mqtt.qos": "2",
           "mqtt.username": " Omit if MQTT broker supports anonymous mode ",
           "mqtt.password": " Omit if MQTT broker supports anonymous mode ",
           "key.converter": "org.apache.kafka.connect.storage.StringConverter",
           "value.converter": "org.apache.kafka.connect.storage.StringConverter",
           "confluent.topic.bootstrap.servers": "kafka:9092",
           "confluent.license": " Omit to enable trial mode ",
           "confluent.topic.replication.factor": "1"
       }
   }
   ```
2. Run this command to start the MQTT sink connector using the Confluent CLI [confluent local services connect connector load](https://docs.confluent.io/confluent-cli/current/command-reference/local/services/connect/connector/confluent_local_services_connect_connector_load.html) command.
   ```bash
   confluent local load mqtt-sink --config mqtt-sink-config.json
   ```

   Your output should resemble:
   ```bash
   {
       "name": "mqtt-sink",
       "config": {
           "connector.class": "io.confluent.connect.mqtt.MqttSinkConnector",
           "tasks.max": "1",
           "mqtt.server.uri": "tcp://127.0.0.1:1881",
           "topics":"kafka-topic-name",
           "mqtt.qos": "2",
           "mqtt.username": " ##### ",
           "mqtt.password": " [hidden] ",
           "key.converter": "org.apache.kafka.connect.storage.StringConverter",
           "value.converter": "org.apache.kafka.connect.storage.StringConverter",
           "confluent.topic.bootstrap.servers": "kafka:9092",
           "confluent.license": " [hidden] ",
           "confluent.topic.replication.factor": "1"
       }
       "tasks": [],
       "type": null
   }
   ```

## Examples

### Property-based example

This configuration is used typically along with [standalone
workers](/platform/current/connect/concepts.html#standalone-workers).

```bash
 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](/platform/current/connect/concepts.html#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](/platform/current/connect/references/restapi.html)

**Connect Distributed REST example:**

```json
 {
   "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**:
  ```bash
  curl -s -X POST -H 'Content-Type: application/json' --data @connector.json http://localhost:8083/connectors
  ```
- **Update an existing connector**:
  ```bash
  curl -s -X PUT -H 'Content-Type: application/json' --data @connector.json http://localhost:8083/connectors/MqttSinkConnector1/config
  ```