Kafka Connect InsertHeader SMT Usage Reference for Confluent Platform

The InsertHeader SMT (org.apache.kafka.connect.transforms.InsertHeader) adds a header with a literal value to each Apache Kafka® record.

Description

Use InsertHeader to add a header with a fixed literal value to every record. Connect parses the literal into the corresponding data type based on its format (for example, 1234 becomes an integer and true becomes a boolean).

Properties

Name	Description	Type	Default	Valid values	Importance
`header`	Header name to use with the transformation.	string		non-null string	high
`value.literal`	The header value to add to each record. If the value appears to be a primitive literal (such as an integer, boolean, or null) or a complex literal (such as an array or map denoted with JSON-like syntax), the value is parsed and added to the header as that type. Otherwise, the raw string for this property is used as-is.	string		non-null string	high

Example

This configuration snippet shows how to use InsertHeader to insert a header named app.id with the literal value best-app-ever on each record.

"transforms": "insertAppIdHeader",
"transforms.insertAppIdHeader.type": "org.apache.kafka.connect.transforms.InsertHeader",
"transforms.insertAppIdHeader.header": "app.id",
"transforms.insertAppIdHeader.value.literal": "best-app-ever"

Before: No header named app.id or value in records.

After: Each record contains header value best-app-ever.

In the preceding example, Connect parses the literal value best-app-ever into STRING type. The following lists sample values for the value.literal property and the data types that Connect parses the value into:

1234 is parsed into INT16 type.
true is parsed into BOOLEAN type.
null is parsed into null (with no type).
[-3, 0, 5] is parsed into an ARRAY of INT8 elements.
{3.4: 4761, -5.9: -9753186420} is parsed into a MAP with FLOAT32 keys and INT64 values.

Predicates

Configure transformations with predicates to ensure they process only records that satisfy a particular condition. You can also use predicates in a transformation chain with the Kafka Connect Filter (Kafka) SMT Usage Reference for Confluent Platform to conditionally filter specific records. For more information, see Predicates.