Kafka Sink Connector Guide

Kafka Sink Connector Configuration Properties¶

Sink Connector Configuration Properties¶

This section lists the available configuration settings used to compose a properties file for the MongoDB Kafka Sink Connector. The connector uses these settings to determine which topics to consume data from and what data to sink to MongoDB. For an example configuration file, see MongoSinkConnector.properties.

Name

Type

Description

topics

list

A list of Kafka topics that the sink connector watches.

Required
Note: You can only define either topics or topics.regex.
Accepted Values: A comma-separated list of valid Kafka topics

topics.regex

string

A regular expression that matches the Kafka topics that the sink connector should watch.

The following regex matches topics such as "activity.landing.clicks" and "activity.support.clicks", but not "activity.landing.views" or "activity.clicks":

topics.regex=activity\\.\\w+\\.clicks$

Required
Note: You can only define either topics or topics.regex.
Accepted Values: A valid regular expression match pattern using java.util.regex.Pattern.

connection.uri

string

A MongoDB connection URI string.

mongodb://username:password@localhost/

For additional information, see the Connect your Kafka Connector to MongoDB section.

Important

Avoid Exposing Your Authentication Credentials

To avoid exposing your authentication credentials in your connection.uri setting, use a ConfigProvider and set the appropriate configuration parameters.

Default: mongodb://localhost:27017

Accepted Values: A valid MongoDB connection URI string

database

string

The name of the MongoDB database the sink writes to.

Required
Accepted Values: A valid MongoDB database name

collection

string

Single sink MongoDB collection name to write to. If the sink follows multiple topics, this is the default collection they are mapped to.

Required
Accepted Values: A MongoDB collection name

namespace.mapper

string

The class name of the class that specifies which database or collection in which to sink the data. The DefaultNamespaceMapper uses the database and collection settings.

Tip

See also:

FieldPathNamespaceMapper settings

Default: com.mongodb.kafka.connect.sink.namespace.mapping.DefaultNamespaceMapper

Accepted Values: A fully qualified Java class name of a class that implements the NamespaceMapper interface.

document.id.strategy

string

The class name of the class that generates a unique document _id field.

Default: com.mongodb.kafka.connect.sink.processor.id.strategy.BsonOidStrategy
Accepted Values: An empty string or a fully qualified Java class name

document.id.strategy.overwrite.existing

boolean

Whether the connector should overwrite existing values in the _id field when the strategy defined in document.id.strategy is applied.

Default: false
Accepted Values: true or false

document.id.strategy.uuid.format

string

Whether the connector should output the UUID in the _id field as a string or in the BsonBinary format.

Default: string
Accepted Values: string or binary

delete.on.null.values

boolean

Whether the connector should delete documents with matching key values when value is null. This setting applies when using an id generation strategy that operates on the key document such as FullKeyStrategy, PartialKeyStrategy, and ProvidedInKeyStrategy.

Default: false
Accepted Values: true or false

max.batch.size

int

The maximum number of sink records to batch together for processing.

Default: 0
Accepted Values: An integer

max.num.retries

int

How many retries should be attempted on write errors.

Default: 1
Accepted Values: An integer

retries.defer.timeout

int

How long (in milliseconds) a retry should get deferred.

Default: 5000
Accepted Values: An integer

change.data.capture.handler

string

The class name of the CDC handler to use for processing.

Default: ""
Accepted Values: An empty string or a fully qualified Java class name

field.renamer.mapping

string

An inline JSON array with objects describing field name mappings.

[ { "oldName":"key.fieldA", "newName":"field1" }, { "oldName":"value.xyz", "newName":"abc" } ]

Default: []

Accepted Values: A valid JSON array

field.renamer.regexp

string

An inline JSON array containing regular expression statement objects.

[ {"regexp":"^key\\\\..*my.*$", "pattern":"my", "replace":""}, {"regexp":"^value\\\\..*$", "pattern":"\\\\.", "replace":"_"} ]

Default: []

Accepted Values: A valid JSON array

key.projection.list

string

A list of field names to include in the key projection.

Default: ""
Accepted Values: A comma-separated list of field names

key.projection.type

string

The type of key projection to use.

Default: none
Accepted Values:  none, BlockList, or AllowList (Deprecated: blacklist, whitelist)

post.processor.chain

list

A list of post-processor classes that process the data before saving it to MongoDB.

Default: com.mongodb.kafka.connect.sink.processor.DocumentIdAdder
Accepted Values: A comma-separated list of fully qualified Java class names

rate.limiting.every.n

int

Number of processed batches that should trigger the rate limit. A value of 0 means no rate limiting.

Default: 0
Accepted Values: An integer

rate.limiting.timeout

int

How long (in milliseconds) to wait before continuing to process data once the rate limit is reached.

Default: 0
Accepted Values: An integer

value.projection.list

string

A list of field names to include in the value projection.

Default: ""
Accepted Values: A comma-separated list of field names

value.projection.type

string

The type of value projection to use.

Default: none
Accepted Values: none, BlockList, or AllowList (Deprecated: blacklist, whitelist)

writemodel.strategy

string

The class that specifies the WriteModel to use for Bulk Writes. See Custom Write Model Strategy for more information.

Default: com.mongodb.kafka.connect.sink.writemodel.strategy.ReplaceOneDefaultStrategy
Accepted Values: A fully qualified Java class name of a class that implements WriteModelStrategy

topic.override.<topicName>.<propertyName>

string

Per-topic configurations that override the corresponding global and default property settings. For example: topic.override.foo.collection=bar instructs the sink connector to store data from the foo topic in the bar collection. For additional examples, see Topic-Specific Configuration Settings.

Note

You can specify any configuration on a per-topic basis except for connection.uri and topics.

Default: ""

Accepted Values: Accepted values specific to the overridden property

tasks.max

int

The maximum number of tasks that should be created for this connector. The connector may create fewer tasks if it cannot handle the specified level of parallelism.

Important

Messages May Be Processed Out of Order for Values Greater Than 1

If you specify a value greater than 1, the connector enables parallel processing of the tasks. If your topic has multiple partition logs (allows consumers to read from the topic in parallel), messages may be processed out of order.

Default: 1

Accepted Values: a positive integer.

heartbeat.interval.ms

int

The length of time in milliseconds between sending heartbeat messages. Heartbeat messages contain the post batch resume token and are sent when no source records have been published in the specified interval. This improves the resumability of the connector for low volume namespaces. Use 0 to disable.

Default: 0
Accepted Values: An integer

heartbeat.topic.name

string

The name of the topic to publish heartbeat messages to. To enable the heartbeat feature, you must provide a positive value in the heartbeat.interval.ms setting. The user must consume messages on this topic to track the latest offset (post batch resume token).

Default: __mongodb_heartbeats
Accepted Values: A valid Kafka topic name

Topic-Specific Configuration Settings¶

The MongoDB Kafka Sink Connector can be configured to sink data from multiple topics. You can override global or default property settings with a topic-specific setting in the form of topic.override.<topicName>.<propertyName>.

Note

The topics and connection.uri properties are global and cannot be overridden.

The following example demonstrates specifying topic-specific settings.

Example: Override Connector Sink Settings on TopicA¶

topic.override.topicA.collection=collectionA
topic.override.topicA.max.batch.size=100
topic.override.topicA.document.id.strategy=com.mongodb.kafka.connect.sink.processor.id.strategy.UuidStrategy
topic.override.topicA.post.processor.chain=com.mongodb.kafka.connect.sink.processor.DocumentIdAdder,com.mongodb.kafka.connect.sink.processor.BlockListValueProjector
topic.override.topicA.value.projection.type=BlockList
topic.override.topicA.value.projection.list=k2,k4

The sink connector topic override settings instruct the connector to apply the following behavior for data consumed from topicA:

Write documents to the MongoDB collection collectionA in batches of up to 100.
Generate a UUID to be stored in the _id field for each new document.
Omit fields k2 and k4 from the value projection using the BlockList projection type.

FieldPathNamespaceMapper Settings¶

You can specify which namespace (database and/or collection) to sink a document based on its field values using the FieldPathNamespaceMapper. To enable this mapper, set the namespace.mapper configuration setting to the class name as shown below:

namespace.mapper=com.mongodb.kafka.connect.sink.topic.mapping.FieldPathNamespaceMapper

The FieldPathNamespaceMapper requires the following:

at least one of the mapping configurations to a database or collection is set
only one of the key or value mapping configurations is set for a mapping to a database
only one of the key or value mapping configurations is set for a mapping to a collection

You can use the following settings to customize the behavior of the FieldPathNamespaceMapper:

Name	Type	Description
namespace.mapper.key.database.field	string	The name of the key document field that specifies the name of the database to write to.
namespace.mapper.key.collection.field	string	The name of the key document field that specifies the name of the collection to write to.
namespace.mapper.value.database.field	string	The name of the value document field that specifies the name of the database to write to.
namespace.mapper.value.collection.field	string	The name of the value document field that specifies the name of the collection to write to.
namespace.mapper.error.if.invalid	boolean	Whether to throw an exception if the document is missing the mapped field or if it contains an invalid BSON type. When set to `true`, the connector does not process the record and may halt or skip processing depending on the related settings. When set to `false` and a document is missing the mapped field or if it contains an invalid BSON type, the connector defaults to writing to the specified `database` and `collection` settings. Default: `false` Accepted Values: `true` or `false`

Dead Letter Queue Configuration Settings¶

Kafka connectors send messages that cannot be processed to the dead letter queue. The connector sends invalid messages to this queue in order to allow manual inspection, updates, and re-submission for processing. It is disabled by default and requires restarting the connector for the changes to the configuration to take effect.

The following is an example configuration for enabling the dead letter queue topic example.deadletterqueue that specifies that both the invalid message as well as the log file should record invalid messages, and that context headers should be included in the dead letter queue messages.

errors.tolerance=all
errors.log.enable=true
errors.log.include.messages=true
errors.deadletterqueue.topic.name=example.deadletterqueue
errors.deadletterqueue.context.headers.enable=true

The table below describes the configuration settings relevant to the dead letter queue.

Name	Type	Description
errors.tolerance	string	Whether to continue processing messages if an error is encountered. When set to `none`, the connector reports an error and blocks further processing of the rest of the records when it encounters an error. When set to `all`, the connector silently ignores any bad messages. Default: "none" Accepted Values: "none" or "all"
errors.log.enable	boolean	Whether details of failed operations should be written to the log file. When set to true, both errors that are tolerated (determined by the errors.tolerance setting) and not tolerated are written. When set to false, errors that are tolerated are omitted. Default: false Accepted Values: `true` or `false`
errors.log.include.messages	boolean	Whether to include the invalid message, including record keys, values, and headers, in the error log file. Default: false Accepted Values: `true` or `false`
errors.deadletterqueue.topic.name	string	Name of topic to use as the dead letter queue. If blank, none of the invalid messages are written to the dead letter queue. Default: "" Accepted Values: A valid Kafka topic name
errors.deadletterqueue.context.headers.enable	boolean	Whether to provide the context headers in messages written to the dead letter queue. Default: false Accepted Values: `true` or `false`
errors.deadletterqueue.topic.replication.factor	integer	The number of nodes on which to replicate the dead letter queue topic. If running a single-node Kafka cluster, this must be set to 1. Default: 3 Accepted Values: A valid number

See the Confluent Sink Connector documentation for more information on these settings.

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