Configuration Reference for MQTT Sink Connector for Confluent Platform

To use this connector, specify the name of the connector class in the connector.class configuration property.

connector.class=io.confluent.connect.mqtt.MqttSinkConnector

Connector-specific configuration properties are described below.

Note

These are properties for the self-managed connector. If you are using Confluent Cloud, see MQTT Sink Connector for Confluent Cloud.

Connection

mqtt.server.uri

List of MQTT brokers to connect to.

  • Type: List
  • Importance: High
mqtt.password

Password to connect with.

  • Type: Password
  • Importance: High
  • Default Value: [hidden]
mqtt.username

Username to connect with, or blank to connect without a username.

  • Type: string
  • Default: “”
  • Importance: high
mqtt.password

Password to connect with, or blank to connect without a password.

  • Type: password
  • Default: [hidden]
  • Importance: high
mqtt.ssl.trust.store.path

The location of the Java TrustStore file containing the certificates required to validate the SSL connection to the server.

  • Type: string
  • Default: “”
  • Importance: high
mqtt.ssl.trust.store.password

Password used to open the Java TrustStore file.

  • Type: password
  • Default: [hidden]
  • Importance: high
mqtt.ssl.key.store.path

The location of the Java KeyStore file containing the private key to use for authenticating with the server.

  • Type: string
  • Default: “”
  • Importance: high
mqtt.ssl.key.store.password

Password used to open the Java KeyStore file.

  • Type: password
  • Default: [hidden]
  • Importance: high
mqtt.ssl.key.password

Password for the client certificate contained in the Java KeyStore.

  • Type: password
  • Default: [hidden]
  • Importance: high
mqtt.clean.session.enabled

Sets whether the client and server should remember state across restarts and reconnects.

  • Type: Boolean
  • Importance: Low
  • Default Value: true

Important

This version of the MQTT Sink Connector doesn’t support persistent connections, meaning the mqtt.clean.session.enabled property is unusable.

mqtt.connect.timeout.seconds

Sets the connection timeout value.

  • Type: Int
  • Importance: Low
  • Default Value: 30
  • Valid Values: [1,…]
mqtt.keepalive.interval.seconds

Sets the “keep alive” interval.

  • Type: Int
  • Importance: Low
  • Default Value: 60
  • Valid Values: [1,…]
max.retry.time.ms

The maximum time in milliseconds (ms) the connector will spend backing off and retrying failed operations (connecting to the MQTT broker and publishing records).

  • Type: long
  • Default: 30000
  • Valid Values: [10000,…,9223372036854775807]
  • Importance: medium

Write

mqtt.qos

The QOS level to write messages to the MQTT broker with.

  • Type: Int
  • Importance: Medium
  • Default Value: 0
  • Valid Values: [0,…,2]
mqtt.retained.enabled

Flag to determine if the messages should be retained.

  • Type: Boolean
  • Importance: Medium
  • Default Value: true

Confluent Platform license

confluent.topic.bootstrap.servers

A list of host/port pairs to use for establishing the initial connection to the Kafka cluster used for licensing. All servers in the cluster will be discovered from the initial connection. This list should be in the form <code>host1:port1,host2:port2,…</code>. Since these servers are just used for the initial connection to discover the full cluster membership (which may change dynamically), this list need not contain the full set of servers (you may want more than one, though, in case a server is down).

  • Type: list
  • Importance: high
confluent.topic

Name of the Kafka topic used for Confluent Platform configuration, including licensing information.

  • Type: string
  • Default: _confluent-command
  • Importance: low
confluent.topic.replication.factor

The replication factor for the Kafka topic used for Confluent Platform configuration, including licensing information. This is used only if the topic does not already exist, and the default of 3 is appropriate for production use. If you are using a development environment with less than 3 brokers, you must set this to the number of brokers (often 1).

  • Type: int
  • Default: 3
  • Importance: low

Confluent license properties

You can put license-related properties in the connector configuration, or starting with Confluent Platform version 6.0, you can put license-related properties in the Connect worker configuration instead of in each connector configuration.

This connector is proprietary and requires a license. The license information is stored in the _confluent-command topic. If the broker requires SSL for connections, you must include the security-related confluent.topic.* properties as described below.

confluent.license

Confluent issues enterprise license keys to each subscriber. The license key is text that you can copy and paste as the value for confluent.license. A trial license allows using the connector for a 30-day trial period. A developer license allows using the connector indefinitely for single-broker development environments.

If you are a subscriber, contact Confluent Support for more information.

  • Type: string
  • Default: “”
  • Valid Values: Confluent Platform license
  • Importance: high
confluent.topic.ssl.truststore.location

The location of the trust store file.

  • Type: string
  • Default: null
  • Importance: high
confluent.topic.ssl.truststore.password

The password for the trust store file. If a password is not set access to the truststore is still available, but integrity checking is disabled.

  • Type: password
  • Default: null
  • Importance: high
confluent.topic.ssl.keystore.location

The location of the key store file. This is optional for client and can be used for two-way authentication for client.

  • Type: string
  • Default: null
  • Importance: high
confluent.topic.ssl.keystore.password

The store password for the key store file. This is optional for client and only needed if ssl.keystore.location is configured.

  • Type: password
  • Default: null
  • Importance: high
confluent.topic.ssl.key.password

The password of the private key in the key store file. This is optional for client.

  • Type: password
  • Default: null
  • Importance: high
confluent.topic.security.protocol

Protocol used to communicate with brokers. Valid values are: PLAINTEXT, SSL, SASL_PLAINTEXT, SASL_SSL.

  • Type: string
  • Default: “PLAINTEXT”
  • Importance: medium

License topic configuration

A Confluent enterprise license is stored in the _confluent-command topic. This topic is created by default and contains the license that corresponds to the license key supplied through the confluent.license property. No public keys are stored in Kafka topics.

The following describes how the default _confluent-command topic is generated under different scenarios:

  • A 30-day trial license is automatically generated for the _confluent command topic if you do not add the confluent.license property or leave this property empty (for example, confluent.license=).
  • Adding a valid license key (for example, confluent.license=<valid-license-key>) adds a valid license in the _confluent-command topic.

Here is an example of the minimal properties for development and testing.

You can change the name of the _confluent-command topic using the confluent.topic property (for instance, if your environment has strict naming conventions). The example below shows this change and the configured Kafka bootstrap server.

confluent.topic=foo_confluent-command
confluent.topic.bootstrap.servers=localhost:9092

The example above shows the minimally required bootstrap server property that you can use for development and testing. For a production environment, you add the normal producer, consumer, and topic configuration properties to the connector properties, prefixed with confluent.topic..

License topic ACLs

The _confluent-command topic contains the license that corresponds to the license key supplied through the confluent.license property. It is created by default. Connectors that access this topic require the following ACLs configured:

  • CREATE and DESCRIBE on the resource cluster, if the connector needs to create the topic.

  • DESCRIBE, READ, and WRITE on the _confluent-command topic.

    Important

    You can also use DESCRIBE and READ without WRITE to restrict access to read-only for license topic ACLs. If a topic exists, the LicenseManager will not try to create the topic.

You can provide access either individually for each principal that will use the license or use a wildcard entry to allow all clients. The following examples show commands that you can use to configure ACLs for the resource cluster and _confluent-command topic.

  1. Set a CREATE and DESCRIBE ACL on the resource cluster:

    kafka-acls --bootstrap-server localhost:9092 --command-config adminclient-configs.conf \
--add --allow-principal User:<principal> \
--operation CREATE --operation DESCRIBE --cluster

  2. Set a DESCRIBE, READ, and WRITE ACL on the _confluent-command topic:

    kafka-acls --bootstrap-server localhost:9092 --command-config adminclient-configs.conf \
--add --allow-principal User:<principal> \
--operation DESCRIBE --operation READ --operation WRITE --topic _confluent-command

Override Default Configuration Properties

You can override the replication factor using confluent.topic.replication.factor. For example, when using a Kafka cluster as a destination with less than three brokers (for development and testing) you should set the confluent.topic.replication.factor property to 1.

You can override producer-specific properties by using the producer.override.* prefix (for source connectors) and consumer-specific properties by using the consumer.override.* prefix (for sink connectors).

You can use the defaults or customize the other properties as well. For example, the confluent.topic.client.id property defaults to the name of the connector with -licensing suffix. You can specify the configuration settings for brokers that require SSL or SASL for client connections using this prefix.

You cannot override the cleanup policy of a topic because the topic always has a single partition and is compacted. Also, do not specify serializers and deserializers using this prefix; they are ignored if added.