Conduit Connector Kafka

The Kafka connector is one of Conduit builtin plugins. It provides both, a source and a destination connector for Apache Kafka.

How to build?

Run make build to build the connector.

Testing

Run make test to run all the unit and integration tests. Tests require Docker to be installed and running. The command will handle starting and stopping docker containers for you.

Tests will run twice, once against an Apache Kafka instance and a second time against a Redpanda instance.

Source

A Kafka source connector is represented by a single consumer in a Kafka consumer group. By virtue of that, a source's logical position is the respective consumer's offset in Kafka. Internally, though, we're not saving the offset as the position: instead, we're saving the consumer group ID, since that's all which is needed for Kafka to find the offsets for our consumer.

A source is getting associated with a consumer group ID the first time the Read() method is called.

Configuration

name	description	required	default value
servers	Servers is a list of Kafka bootstrap servers, which will be used to discover all the servers in a cluster.	true
topics	Topics is a comma separated list of Kafka topics from which records will be read, ex: "topic1,topic2".	true
topic	Topic is the Kafka topic to read from. Deprecated: use topics instead.	false
clientID	A Kafka client ID.	false	conduit-connector-kafka
readFromBeginning	Determines from whence the consumer group should begin consuming when it finds a partition without a committed offset. If this option is set to true it will start with the first message in that partition.	false	false
groupID	Defines the consumer group ID.	false
tls.enabled	Defines whether TLS is enabled.	false	false
clientCert	A certificate for the Kafka client, in PEM format. If provided, the private key needs to be provided too.	false
clientKey	A private key for the Kafka client, in PEM format. If provided, the certificate needs to be provided too.	false
caCert	The Kafka broker's certificate, in PEM format.	false
insecureSkipVerify	Controls whether a client verifies the server's certificate chain and host name. If true, accepts any certificate presented by the server and any host name in that certificate.	false	false
saslMechanism	SASL mechanism to be used. Possible values: PLAIN, SCRAM-SHA-256, SCRAM-SHA-512. If empty, authentication won't be performed.	false
saslUsername	SASL username. If provided, a password needs to be provided too.	false
saslPassword	SASL password. If provided, a username needs to be provided too.	false
retryGroupJoinErrors	determines whether the connector will continually retry on group join errors	false	true

Destination

The destination connector sends records to Kafka.

Configuration

There's no global, connector configuration. Each connector instance is configured separately.

name	description	required	default value
servers	Servers is a list of Kafka bootstrap servers, which will be used to discover all the servers in a cluster.	true
topic	Topic is the Kafka topic. It can contain a Go template that will be executed for each record to determine the topic. By default, the topic is the value of the opencdc.collection metadata field.	false	{{ index .Metadata "opencdc.collection" }}
clientID	A Kafka client ID.	false	conduit-connector-kafka
acks	Acks defines the number of acknowledges from partition replicas required before receiving a response to a produce request. none = fire and forget, one = wait for the leader to acknowledge the writes, all = wait for the full ISR to acknowledge the writes.	false	all
deliveryTimeout	Message delivery timeout.	false
batchBytes	Limits the maximum size of a request in bytes before being sent to a partition. This mirrors Kafka's max.message.bytes.	false	1000012
compression	Compression applied to messages. Possible values: none, gzip, snappy, lz4, zstd.	false	snappy
clientCert	A certificate for the Kafka client, in PEM format. If provided, the private key needs to be provided too.	false
clientKey	A private key for the Kafka client, in PEM format. If provided, the certificate needs to be provided too.	false
caCert	The Kafka broker's certificate, in PEM format.	false
insecureSkipVerify	Controls whether a client verifies the server's certificate chain and host name. If true, accepts any certificate presented by the server and any host name in that certificate.	false	false
saslMechanism	SASL mechanism to be used. Possible values: PLAIN, SCRAM-SHA-256, SCRAM-SHA-512. If empty, authentication won't be performed.	false
saslUsername	SASL username. If provided, a password needs to be provided too.	false
saslPassword	SASL password. If provided, a username needs to be provided too.	false

Output format

The output format can be adjusted using configuration options provided by the connector SDK:

• sdk.record.format: used to choose the format
• sdk.record.format.options: used to configure the specifics of the chosen format

See this article for more info on configuring the output format.

Batching

Batching can also be configured using connector SDK provided options:

• sdk.batch.size: maximum number of records in batch before it gets written to the destination (defaults to 0, no batching)
• sdk.batch.delay: maximum delay before an incomplete batch is written to the destination (defaults to 0, no limit)