--- title: Application Reset Tool description: weight: 13 tags: ['kafka', 'docs'] aliases: keywords: type: docs --- You can reset an application and force it to reprocess its data from scratch by using the application reset tool. This can be useful for development and testing, or when fixing bugs. The application reset tool handles the Kafka Streams [user topics](manage-topics.html#streams-developer-guide-topics-user) (input, and output) and [internal topics](manage-topics.html#streams-developer-guide-topics-internal) differently when resetting the application. Here's what the application reset tool does for each topic type: * Input topics: Reset offsets to specified position (by default to the beginning of the topic). * Internal topics: Delete the internal topic (this automatically deletes any committed offsets). The application reset tool does not: * Reset output topics of an application. If any output topics are consumed by downstream applications, it is your responsibility to adjust those downstream applications as appropriate when you reset the upstream application. * Reset the local environment of your application instances. It is your responsibility to delete the local state on any machine on which an application instance was run. See the instructions in section Step 2: Reset the local environments of your application instances on how to do this. Prerequisites * All instances of your application must be stopped. Otherwise, the application may enter an invalid state, crash, or produce incorrect results. You can verify whether the consumer group with ID `application.id` is still active by using `bin/kafka-consumer-groups`. When long session timeout has been configured, active members could take longer to get expired on the broker thus blocking the reset job to complete. Use the `--force` option could remove those left-over members immediately. Make sure to shut down all stream applications when this option is specified to avoid unexpected rebalances. * Use this tool with care and double-check its parameters: If you provide wrong parameter values (e.g., typos in `application.id`) or specify parameters inconsistently (e.g., specify the wrong input topics for the application), this tool might invalidate the application's state or even impact other applications, consumer groups, or your Kafka topics. # Step 1: Run the application reset tool If you are using **streams rebalance protocol** (available since AK 4.2), use the [Streams groups CLI](kafka-streams-group-sh#reset-offsets). If you are using **classic rebalance protocol** , run the classic application reset tool as described below. Invoke the application reset tool from the command line Warning! This tool makes irreversible changes to your application. It is strongly recommended that you run this once with `--dry-run` to preview your changes before making them. $ bin/kafka-streams-application-reset.sh The tool accepts the following parameters: Option (* = required) Description --------------------- ----------- * --application-id REQUIRED: The Kafka Streams application ID (application.id). --bootstrap-server The broker list string in the form HOST1:PORT1,HOST2:PORT2. (default: localhost:9092) --by-duration Reset offsets to offset by duration from current timestamp. Format: 'PnDTnHnMnS' --config-file (Deprecated) Property file containing configs to be passed to admin clients and embedded consumer. This option will be removed in a future version. Use --command-config instead. --command-config Config properties file to be passed to admin clients and embedded consumer. --dry-run Display the actions that would be performed without executing the reset commands. --from-file Reset offsets to values defined in CSV file. --input-topics Comma-separated list of user input topics. For these topics, the tool will reset the offset to the earliest available offset. --internal-topics Comma-separated list of internal topics to delete. Must be a subset of the internal topics marked for deletion by the default behaviour (do a dry-run without this option to view these topics). --shift-by Reset offsets shifting current offset by 'n', where 'n' can be positive or negative --to-datetime Reset offsets to offset from datetime. Format: 'YYYY-MM-DDThh:mm:ss.sss' --to-earliest Reset offsets to earliest offset. --to-latest Reset offsets to latest offset. --to-offset Reset offsets to a specific offset. --force Force removing members of the consumer group (intended to remove left-over members if long session timeout was configured). Consider the following as reset-offset scenarios for `input-topics`: * by-duration * from-file * shift-by * to-datetime * to-earliest * to-latest * to-offset Only one of these scenarios can be defined. If not, `to-earliest` will be executed by default All the other parameters can be combined as needed. For example, if you want to restart an application from an empty internal state, but not reprocess previous data, simply omit the parameter `--input-topics`. # Step 2: Reset the local environments of your application instances For a complete application reset, you must delete the application's local state directory on any machines where the application instance was run. You must do this before restarting an application instance on the same machine. You can use either of these methods: * The API method `KafkaStreams#cleanUp()` in your application code. * Manually delete the corresponding local state directory (default location: `/${java.io.tmpdir}/kafka-streams/`). For more information, see [Streams](/{version}/javadoc/org/apache/kafka/streams/StreamsConfig.html#STATE_DIR_CONFIG) javadocs. * [Documentation](/documentation) * [Kafka Streams](/documentation/streams) * [Developer Guide](/documentation/streams/developer-guide/)