<a id="tombstonehandler"></a>

# Kafka Connect TombstoneHandler SMT Usage Reference for Confluent Platform

The `TombstoneHandler` SMT (`io.confluent.connect.transforms.TombstoneHandler`)
manages tombstone records within a Connect data pipeline.

## Description

A tombstone record is any Apache Kafka® record whose entire `value` field is
`null`, regardless of whether a value schema is present.

Many downstream systems and sink connectors cannot natively process empty
payloads without throwing exceptions. This SMT provides a mechanism to
intercept them. Depending on your configuration, the
`TombstoneHandler` can be set to silently ignore, log a warning, or fail the
execution when a tombstone record is processed.

## Installation

This transformation is developed by Confluent and does not ship by default
with Kafka or Confluent Platform. You can install this transformation using the
[confluent connect plugin
install](https://docs.confluent.io/confluent-cli/current/command-reference/connect/plugin/confluent_connect_plugin_install.html)
command:

```properties
confluent connect plugin install confluentinc/connect-transforms:latest
```

<a id="tombstonehandler-properties"></a>

## Properties

| Name       | Description                                                                                                                                                                                                                                                                                                                       | Type   | Default   | Valid values         | Importance   |
|------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|-----------|----------------------|--------------|
| `behavior` | If set to `ignore`, the tombstone<br/>record is ignored silently, with a DEBUG message written to log.<br/>If set to `warn`, the tombstone record is ignored silently,<br/>with a WARN message written to log. If set to `fail`, the execution<br/>fails, a `DataException` is thrown, and a DEBUG message is<br/>written to log. | string | warn      | [ignore, warn, fail] | medium       |

## Examples

The following snippets show how to configure the `TombstoneHandler` SMT for
each supported `behavior` value:

| Behavior         | Description                                                          |
|------------------|----------------------------------------------------------------------|
| `warn` (default) | Drops the tombstone record and logs a WARN message.                  |
| `ignore`         | Drops the tombstone record and logs a DEBUG message.                 |
| `fail`           | Fails execution, throws a `DataException`, and logs a DEBUG message. |

### Handle tombstones with the default (warn) behavior

```json
"transforms": "tombstoneHandlerExample",
"transforms.tombstoneHandlerExample.type": "io.confluent.connect.transforms.TombstoneHandler"
```

### Ignore tombstone records

```json
"transforms.tombstoneHandlerExample.type": "io.confluent.connect.transforms.TombstoneHandler",
"transforms.tombstoneHandlerExample.behavior": "ignore"
```

### Fail on tombstone records

```json
"transforms.tombstoneHandlerExample.type": "io.confluent.connect.transforms.TombstoneHandler",
"transforms.tombstoneHandlerExample.behavior": "fail"
```

## 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](filter-ak.md#ak-filter) to conditionally filter specific
records. For more information, see [Predicates](filter-ak.md#predicates).