# Kafka Connect InsertHeader SMT Usage Reference for Confluent Cloud The following provides usage information for the Apache Kafka® SMT `org.apache.kafka.connect.transforms.InsertHeader`. ## Description Inserts a header for each record. ## 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. ```json "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 example above, Connect parses the literal value `best-app-ever` into [STRING type](https://docs.confluent.io/platform/current/connect/javadocs/javadoc/org/apache/kafka/connect/data/Schema.Type.html#STRING). The following lists sample values for the value property and the data types that Connect parses the value into: * `1234` is parsed into [INT16 type](https://docs.confluent.io/platform/current/connect/javadocs/javadoc/org/apache/kafka/connect/data/Schema.Type.html#INT16). * `true` is parsed into [BOOLEAN type](https://docs.confluent.io/platform/current/connect/javadocs/javadoc/org/apache/kafka/connect/data/Schema.Type.html#BOOLEAN). * `null` is parsed into null (with no type). * `[-3, 0, 5]` is parsed into an [ARRAY](https://docs.confluent.io/platform/current/connect/javadocs/javadoc/org/apache/kafka/connect/data/Schema.Type.html#ARRAY) of [INT8 elements](https://docs.confluent.io/platform/current/connect/javadocs/javadoc/org/apache/kafka/connect/data/Schema.Type.html#INT8). * `{3.4: 4761, -5.9: -9753186420}` is parsed into a [MAP](https://docs.confluent.io/platform/current/connect/javadocs/javadoc/org/apache/kafka/connect/data/Schema.Type.html#MAP) with [FLOAT32 keys](https://docs.confluent.io/platform/current/connect/javadocs/javadoc/org/apache/kafka/connect/data/Schema.Type.html#FLOAT32) and [INT64 values](https://docs.confluent.io/platform/current/connect/javadocs/javadoc/org/apache/kafka/connect/data/Schema.Type.html#INT64). ## Properties | Name | Description | Type | Default | Valid Values | Importance | |----------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|-----------|-----------------|--------------| | `header` | Header name to use with the transformation. | string | | non-null string | medium | | `value` | The header value to add to each record. If the value appears to be a primitive literal (such as a 32-bit 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 | medium | ## Predicates Transformations can be configured with *predicates* so that the transformation is applied only to records which satisfy a condition. You can use predicates in a transformation chain and, when combined with the [Kafka Connect Filter (Kafka) SMT Usage Reference for Confluent Cloud](filter-ak.md#ak-filter), predicates can conditionally filter out specific records. For details and examples, see [Predicates](filter-ak.md#predicates).