PublishKafka

Description:

Sends the contents of a FlowFile as a message to Apache Kafka using the Kafka 0.9.x Producer. The messages to send may be individual FlowFiles or may be delimited, using a user-specified delimiter, such as a new-line. Please note there are cases where the publisher can get into an indefinite stuck state. We are closely monitoring how this evolves in the Kafka community and will take advantage of those fixes as soon as we can. In the mean time it is possible to enter states where the only resolution will be to restart the JVM NiFi runs on. The complementary NiFi processor for fetching messages is ConsumeKafka.

Additional Details...

Tags:

Apache, Kafka, Put, Send, Message, PubSub, 0.9.x

Properties:

In the list below, the names of required properties appear in bold. Any other properties (not in bold) are considered optional. The table also indicates any default values, and whether a property supports the NiFi Expression Language.

NameDefault ValueAllowable ValuesDescription
Kafka Brokerslocalhost:9092A comma-separated list of known Kafka Brokers in the format <host>:<port>
Supports Expression Language: true
Security ProtocolPLAINTEXT
  • PLAINTEXT PLAINTEXT
  • SSL SSL
  • SASL_PLAINTEXT SASL_PLAINTEXT
  • SASL_SSL SASL_SSL
Protocol used to communicate with brokers. Corresponds to Kafka's 'security.protocol' property.
Kerberos Service NameThe Kerberos principal name that Kafka runs as. This can be defined either in Kafka's JAAS config or in Kafka's config. Corresponds to Kafka's 'security.protocol' property.It is ignored unless one of the SASL options of the <Security Protocol> are selected.
SSL Context ServiceController Service API:
SSLContextService
Implementations: StandardSSLContextService
StandardRestrictedSSLContextService
Specifies the SSL Context Service to use for communicating with Kafka.
Topic NameThe name of the Kafka Topic to publish to.
Supports Expression Language: true
Delivery Guarantee0
  • Best Effort FlowFile will be routed to success after successfully writing the content to a Kafka node, without waiting for a response. This provides the best performance but may result in data loss.
  • Guarantee Single Node Delivery FlowFile will be routed to success if the message is received by a single Kafka node, whether or not it is replicated. This is faster than <Guarantee Replicated Delivery> but can result in data loss if a Kafka node crashes
  • Guarantee Replicated Delivery FlowFile will be routed to failure unless the message is replicated to the appropriate number of Kafka Nodes according to the Topic configuration
Specifies the requirement for guaranteeing that a message is sent to Kafka. Corresponds to Kafka's 'acks' property.
Kafka KeyThe Key to use for the Message. If not specified, the flow file attribute 'kafka.key' is used as the message key, if it is present.Beware that setting Kafka key and demarcating at the same time may potentially lead to many Kafka messages with the same key.Normally this is not a problem as Kafka does not enforce or assume message and key uniqueness. Still, setting the demarcator and Kafka key at the same time poses a risk of data loss on Kafka. During a topic compaction on Kafka, messages will be deduplicated based on this key.
Supports Expression Language: true
Key Attribute Encodingutf-8
  • UTF-8 Encoded The key is interpreted as a UTF-8 Encoded string.
  • Hex Encoded The key is interpreted as arbitrary binary data that is encoded using hexadecimal characters with uppercase letters.
FlowFiles that are emitted have an attribute named 'kafka.key'. This property dictates how the value of the attribute should be encoded.
Message DemarcatorSpecifies the string (interpreted as UTF-8) to use for demarcating multiple messages within a single FlowFile. If not specified, the entire content of the FlowFile will be used as a single message. If specified, the contents of the FlowFile will be split on this delimiter and each section sent as a separate Kafka message. To enter special character such as 'new line' use CTRL+Enter or Shift+Enter, depending on your OS.
Supports Expression Language: true
Max Request Size1 MBThe maximum size of a request in bytes. Corresponds to Kafka's 'max.request.size' property and defaults to 1 MB (1048576).
Acknowledgment Wait Time5 secsAfter sending a message to Kafka, this indicates the amount of time that we are willing to wait for a response from Kafka. If Kafka does not acknowledge the message within this time period, the FlowFile will be routed to 'failure'.
Max Metadata Wait Time5 secThe amount of time publisher will wait to obtain metadata or wait for the buffer to flush during the 'send' call before failing the entire 'send' call. Corresponds to Kafka's 'max.block.ms' property
Supports Expression Language: true
Partitioner classorg.apache.kafka.clients.producer.internals.DefaultPartitioner
  • RoundRobinPartitioner Messages will be assigned partitions in a round-robin fashion, sending the first message to Partition 1, the next Partition to Partition 2, and so on, wrapping as necessary.
  • DefaultPartitioner Messages will be assigned to random partitions.
Specifies which class to use to compute a partition id for a message. Corresponds to Kafka's 'partitioner.class' property.
Compression Typenone
  • none
  • gzip
  • snappy
  • lz4
This parameter allows you to specify the compression codec for all data generated by this producer.

Dynamic Properties:

Dynamic Properties allow the user to specify both the name and value of a property.

NameValueDescription
The name of a Kafka configuration property.The value of a given Kafka configuration property.These properties will be added on the Kafka configuration after loading any provided configuration properties. In the event a dynamic property represents a property that was already set, its value will be ignored and WARN message logged. For the list of available Kafka properties please refer to: http://kafka.apache.org/documentation.html#configuration.

Relationships:

NameDescription
successFlowFiles for which all content was sent to Kafka.
failureAny FlowFile that cannot be sent to Kafka will be routed to this Relationship

Reads Attributes:

None specified.

Writes Attributes:

NameDescription
msg.countThe number of messages that were sent to Kafka for this FlowFile. This attribute is added only to FlowFiles that are routed to success. If the <Message Demarcator> Property is not set, this will always be 1, but if the Property is set, it may be greater than 1.

State management:

This component does not store state.

Restricted:

This component is not restricted.

Input requirement:

This component requires an incoming relationship.

System Resource Considerations:

None specified.