Kamelet Catalog

kafka source Kafka Source

Provided by: "Apache Software Foundation"

Support Level for this Kamelet is: "Stable"

Receive data from Kafka topics.

Configuration Options

The following table summarizes the configuration options available for the kafka-source Kamelet:

Property Name Description Type Default Example

bootstrapServers

Bootstrap Servers

Required Comma separated list of Kafka Broker URLs.

string

topic

Topic Names

Required Comma separated list of Kafka topic names.

string

allowManualCommit

Allow Manual Commit

Whether to allow doing manual commits.

boolean

false

autoCommitEnable

Auto Commit Enable

If true, periodically commit to ZooKeeper the offset of messages already fetched by the consumer.

boolean

true

autoOffsetReset

Auto Offset Reset

What to do when there is no initial offset. There are 3 enums and the value can be one of latest, earliest, none.

string

latest

consumerGroup

Consumer Group

A string that uniquely identifies the group of consumers to which this source belongs.

string

my-group-id

deserializeHeaders

Automatically Deserialize Headers

When enabled the Kamelet source will deserialize all message headers to String representation.

boolean

true

oauthClientId

OAuth Client ID

OAuth client ID. Required when saslAuthType is OAUTH.

string

oauthClientSecret

OAuth Client Secret

OAuth client secret. Required when saslAuthType is OAUTH.

string

oauthScope

OAuth Scope

OAuth scope. Optional when saslAuthType is OAUTH.

string

oauthTokenEndpointUri

OAuth Token Endpoint

OAuth token endpoint URI. Required when saslAuthType is OAUTH.

string

pollOnError

Poll On Error Behavior

What to do if kafka threw an exception while polling for new messages. There are 5 enums and the value can be one of DISCARD, ERROR_HANDLER, RECONNECT, RETRY, STOP.

string

ERROR_HANDLER

saslAuthType

Authentication Type

Authentication type to use. Use NONE for no authentication, PLAIN or SCRAM_SHA_256/SCRAM_SHA_512 for username/password, SSL for certificate-based, OAUTH for OAuth 2.0, AWS_MSK_IAM for MSK, or KERBEROS for Kerberos.

Enum values:

* NONE * PLAIN * SCRAM_SHA_256 * SCRAM_SHA_512 * SSL * OAUTH * AWS_MSK_IAM * KERBEROS

string

NONE

saslPassword

Password

Password for SASL authentication. Required when saslAuthType is PLAIN, SCRAM_SHA_256, or SCRAM_SHA_512.

string

saslUsername

Username

Username for SASL authentication. Required when saslAuthType is PLAIN, SCRAM_SHA_256, or SCRAM_SHA_512.

string

sslKeyPassword

SSL Key Password

The password of the private key in the key store file.

string

sslKeystoreLocation

SSL Keystore Location

The location of the key store file. Used for mTLS authentication.

string

sslKeystorePassword

SSL Keystore Password

The password for the key store file.

string

sslTruststoreLocation

SSL Truststore Location

The location of the trust store file.

string

sslTruststorePassword

SSL Truststore Password

The password for the trust store file.

string

topicIsPattern

Topic Is Pattern

Whether the topic is a pattern (regular expression). This can be used to subscribe to dynamic number of topics matching the pattern.

boolean

false

Dependencies

At runtime, the kafka-source Kamelet relies upon the presence of the following dependencies:

  • camel:core

  • camel:kafka

  • camel:kamelet

Camel JBang usage

Prerequisites

  • You’ve installed JBang.

  • You have executed the following command:

jbang app install camel@apache/camel

Supposing you have a file named route.yaml with this content:

- route:
    from:
      uri: "kamelet:kafka-source"
      parameters:
        .
        .
        .
      steps:
        - to:
            uri: "kamelet:log-sink"

You can now run it directly through the following command

camel run route.yaml

Kafka Source Kamelet Description

Authentication

Authentication is selected with saslAuthType, which defaults to NONE, so out of the box the Kamelet connects to an unauthenticated broker. The accepted values are NONE, PLAIN, SCRAM_SHA_256, SCRAM_SHA_512, SSL, OAUTH, AWS_MSK_IAM and KERBEROS.

Which other properties are needed depends on that choice:

  • PLAIN, SCRAM_SHA_256 and SCRAM_SHA_512 take saslUsername and saslPassword.

  • OAUTH takes oauthClientId, oauthClientSecret, oauthTokenEndpointUri and oauthScope.

  • SSL takes the keystore and truststore properties below.

  • AWS_MSK_IAM and KERBEROS rely on the surrounding environment rather than on Kamelet properties.

Resolve credentials through a Camel vault rather than plaintext properties wherever the deployment allows it.

Configuration

Only topic and bootstrapServers are required. The Kamelet supports:

  • topic: Comma-separated list of Kafka topic names to consume from (required)

  • bootstrapServers: Comma-separated list of Kafka bootstrap servers (required)

  • saslAuthType: Authentication mechanism, default NONE

  • saslUsername / saslPassword: Credentials for the username and password mechanisms

  • oauthClientId / oauthClientSecret / oauthTokenEndpointUri / oauthScope: OAuth 2.0 settings

  • sslTruststoreLocation / sslTruststorePassword / sslKeystoreLocation / sslKeystorePassword / sslKeyPassword: TLS material

  • consumerGroup: Kafka consumer group ID for managing offsets

  • autoOffsetReset: What to do when there is no initial offset - earliest, latest or none, default latest

  • autoCommitEnable: Commit offsets automatically, default true

  • allowManualCommit: Enable manual commit for control over when offsets advance, default false

  • pollOnError: What to do when polling fails, default ERROR_HANDLER

  • deserializeHeaders: Deserialize the Kafka record headers onto the exchange, default true

  • topicIsPattern: Treat topic as a regular expression rather than a literal list, default false

Output Format

The body is the Kafka record value. The record metadata is surfaced as headers under names that are not Camel internals, so a downstream consumer does not have to read the CamelKafka* headers directly. Each has a ce- prefixed CloudEvents counterpart as well.

  • kafka-topic from CamelKafkaTopic - the topic the record was consumed from, which is worth having when the Kamelet subscribes to several topics or to a pattern.

  • kafka-key from CamelKafkaKey - the record key, absent for records produced without one.

  • kafka-partition from CamelKafkaPartition - the partition the record came from.

  • kafka-offset from CamelKafkaOffset - the offset within that partition.

  • kafka-timestamp from CamelKafkaTimestamp - the record timestamp, in milliseconds since the epoch.

The CamelKafka* headers are left on the exchange as well, so consumers already reading them keep working. The Kafka record headers are passed through separately, controlled by the deserializeHeaders property.

Usage Example

- route:
    from:
      uri: "kamelet:kafka-source"
      parameters:
        topic: "orders,payments"
        bootstrapServers: "kafka.example.com:9092"
        saslAuthType: "PLAIN"
        saslUsername: "kafka-user"
        saslPassword: "kafka-password"
      steps:
        - to:
            uri: "kamelet:log-sink"

Example with Consumer Group

- route:
    from:
      uri: "kamelet:kafka-source"
      parameters:
        topic: "user-events"
        bootstrapServers: "kafka1.example.com:9092,kafka2.example.com:9092"
        saslAuthType: "PLAIN"
        saslUsername: "kafka-user"
        saslPassword: "kafka-password"
        consumerGroup: "my-consumer-group"
        autoOffsetReset: "earliest"
      steps:
        - to:
            uri: "kamelet:log-sink"

Security

Nothing is enabled by default: saslAuthType is NONE and no TLS material is configured, so an unconfigured binding talks to the broker in the clear. Set saslAuthType and the matching properties for the mechanism the broker expects, and supply the truststore and keystore properties for a TLS listener.

Error Handling

The consumer automatically handles connection failures and will attempt to reconnect to the Kafka cluster. Failed message processing can be handled through Camel’s error handling mechanisms.

Kamelet source file

https://github.com/apache/camel-kamelets/blob/main/kamelets/kafka-source.kamelet.yaml