[Yandex Cloud documentation](../../index.md) > [Tutorials](../index.md) > [Building a data platform](index.md) > Moving data between Managed Service for Apache Kafka® clusters using Data Transfer

# Moving data between Managed Service for Apache Kafka® clusters using Data Transfer

# Migrating data between Apache Kafka® clusters using Yandex Data Transfer


You can transfer your data from Apache Kafka® topics between one Apache Kafka® cluster and another in real time. Among others, the following migration types are supported:

* Between different Apache Kafka® versions, e.g., you can migrate topics from version 2.8 to version 3.1.
* Between different availability zones: you can [migrate a cluster with a single host](../../managed-kafka/operations/host-migration.md#one-host) from one zone to another.

Apache Kafka® cluster mirroring allows you to:

* Set up topic replication in the management console interface or in Terraform.
* Track the migration process using the [transfer monitoring](../../data-transfer/operations/monitoring.md).
* Eliminate the need for an intermediate VM or public internet access to your target cluster.

{% note info %}

This tutorial describes a scenario for migrating data from one Managed Service for Apache Kafka® cluster to another.

{% endnote %}

To migrate data:

1. [Prepare and activate your transfer](#prepare-transfer).
1. [Test the transfer](#verify-transfer).

If you no longer need the resources you created, [delete them](#clear-out).


## Required paid resources {#paid-resources}

* Managed Service for Apache Kafka® clusters: computing resources allocated to hosts, storage and backup size (see [Managed Service for Apache Kafka® pricing](../../managed-kafka/pricing.md)).
* Public IP addresses if public access is enabled for cluster hosts (see [Virtual Private Cloud pricing](../../vpc/pricing.md)).
* Each transfer: use of computing resources and the number of transferred data rows (see [Data Transfer pricing](../../data-transfer/pricing.md)).


## Getting started {#before-you-begin}

1. Set up your data delivery infrastructure:

   {% list tabs group=instructions %}

   - Manually {#manual}

       1. [Create a source and target Managed Service for Apache Kafka® cluster](../../managed-kafka/operations/cluster-create.md) of any suitable configuration with public access from the internet.

                        
            {% note info %}
            
            Public access to cluster hosts is required if you plan to connect to the cluster via the internet. This connection option is simpler and is recommended for the purposes of this guide. You can connect to non-public hosts as well but only from Yandex Cloud virtual machines located in the same cloud network as the cluster.
            
            {% endnote %}


       1. [In the source cluster, create a topic](../../managed-kafka/operations/cluster-topics.md#create-topic) named `sensors`.
       1. [In the source cluster, create a user](../../managed-kafka/operations/cluster-accounts.md#create-account) with the `ACCESS_ROLE_PRODUCER` and `ACCESS_ROLE_CONSUMER` permissions for the new topic.
       1. [In the target cluster, create a user](../../managed-kafka/operations/cluster-accounts.md#create-account) with the `ACCESS_ROLE_PRODUCER` and `ACCESS_ROLE_CONSUMER` permissions for all topics.

   
   - Terraform {#tf}

       1. If you do not have Terraform yet, [install it](../infrastructure-management/terraform-quickstart.md#install-terraform).
       1. [Get the authentication credentials](../infrastructure-management/terraform-quickstart.md#get-credentials). You can add them to environment variables or specify them later in the provider configuration file.
       1. [Configure and initialize a provider](../infrastructure-management/terraform-quickstart.md#configure-provider). There is no need to create a provider configuration file manually, you can [download it](https://github.com/yandex-cloud-examples/yc-terraform-provider-settings/blob/main/provider.tf).
       1. Place the configuration file in a separate working directory and [specify the parameter values](../infrastructure-management/terraform-quickstart.md#configure-provider). If you did not add the authentication credentials to environment variables, specify them in the configuration file.

       1. Download the [data-transfer-mkf-mkf.tf](https://github.com/yandex-cloud-examples/yc-data-transfer-mirror-managed-kafka/blob/main/data-transfer-mkf-mkf.tf) configuration file to the same working directory.

           This file describes:

           * [Network](../../vpc/concepts/network.md#network).
           * [Subnet](../../vpc/concepts/network.md#subnet).
           * [Security group](../../vpc/concepts/security-groups.md) and the rule required for connecting to the Managed Service for Apache Kafka® cluster.
           * Managed Service for Apache Kafka® source cluster with public access from the internet.
           * Apache Kafka® topic for the source cluster.
           * Apache Kafka® user for the source cluster.
           * Managed Service for Apache Kafka® target cluster with public internet access.
           * Apache Kafka® topic for the target cluster.
           * Apache Kafka® user for the target cluster.
           * Source and target endpoints.
           * Transfer.

       1. In the `data-transfer-mkf-mkf.tf` file, specify the following settings:

           * `source_kf_version`: Apache Kafka® version in the source cluster.
           * `source_user_name`: Username for connection to the Apache Kafka® topic.
           * `source_user_password`: Password.
           * `target_kf_version`: Apache Kafka® version in the target cluster.
           * `target_user_name`: Username for connection to the Apache Kafka® topic.
           * `target_user_password`: Password.
           * `transfer_enabled = 0`: Disables the creation of endpoints and transfers. They will be created during the [preparation of the transfer](#prepare-transfer).

       1. Validate your Terraform configuration files using this command:

           ```bash
           terraform validate
           ```

           Terraform will display any configuration errors detected in your files.

       1. Create the required infrastructure:

           1. Run this command to view the planned changes:
           
              ```bash
              terraform plan
              ```
           
              If you described the configuration correctly, the terminal will display a list of the resources to update and their parameters. This is a verification step that does not apply changes to your resources.
           
           1. If everything looks correct, apply the changes:
              1. Run this command:
           
                 ```bash
                 terraform apply
                 ```
           
              1. Confirm updating the resources.
              1. Wait for the operation to complete.

           All the required resources will be created in the specified folder. You can check resource availability and their settings in the [management console](https://console.yandex.cloud).


   {% endlist %}

   The source cluster's new Apache Kafka® topic, `sensors`, will receive test data from car sensors in JSON format, for example:

   ```json
   {
       "device_id":"iv9a94th6rzt********",
       "datetime":"2020-06-05 17:27:00",
       "latitude":"55.70329032",
       "longitude":"37.65472196",
       "altitude":"427.5",
       "speed":"0",
       "battery_voltage":"23.5",
       "cabin_temperature":"17",
       "fuel_level":null
   }
   ```

1. Install these tools:

    - [kafkacat](https://github.com/edenhill/kcat): For reading from and writing to Apache Kafka® topics.

        ```bash
        sudo apt update && sudo apt install --yes kafkacat
        ```

        Check that you can use it to [connect to the Managed Service for Apache Kafka® source cluster over SSL](../../managed-kafka/operations/connect/clients.md#bash-zsh).

    - [jq](https://stedolan.github.io/jq/): For stream processing of JSON files.

        ```bash
        sudo apt update && sudo apt-get install --yes jq
        ```

## Prepare and activate a transfer {#prepare-transfer}

{% list tabs group=instructions %}

- Manually {#manual}

  1. [Create a target endpoint](../../data-transfer/operations/endpoint/index.md#create):

      * **Database type**: `Kafka`.
      * **Endpoint parameters**:

         * **Connection settings**: `Managed Service for Apache Kafka cluster`.

           Select your target cluster from the list and specify its connection settings.

         * **Topic**:
           * **Topic full name**: `measurements`.

  1. [Create a source endpoint](../../data-transfer/operations/endpoint/index.md#create):

      * **Database type**: `Kafka`.
      * **Endpoint parameters**:
        * **Connection type**: `Managed Service for Apache Kafka cluster`.

          Select your source cluster from the list and specify its connection settings.

        * **Topic full name**: `sensors`.

  1. [Create a transfer](../../data-transfer/operations/transfer.md#create) of the **Replication** type that will use the endpoints you created.
  1. [Activate](../../data-transfer/operations/transfer.md#activate) the transfer.


- Terraform {#tf}

  1. Specify `transfer_enabled = 1` in the `data-transfer-mkf-mkf.tf` file.

  1. Validate your Terraform configuration files using this command:

      ```bash
      terraform validate
      ```

      Terraform will display any configuration errors detected in your files.

  1. Create the required infrastructure:

      1. Run this command to view the planned changes:
      
         ```bash
         terraform plan
         ```
      
         If you described the configuration correctly, the terminal will display a list of the resources to update and their parameters. This is a verification step that does not apply changes to your resources.
      
      1. If everything looks correct, apply the changes:
         1. Run this command:
      
            ```bash
            terraform apply
            ```
      
         1. Confirm updating the resources.
         1. Wait for the operation to complete.

      Endpoints and a transfer will be created. The transfer will be activated automatically as soon as it is created.


{% endlist %}

## Test the transfer {#verify-transfer}

1. Wait for the transfer status to change to **Replicating**.
1. Make sure data from the Managed Service for Apache Kafka® source cluster topic can be transferred to the target cluster topic:

    1. Create a file named `sample.json` with test data:

        ```json
        {
            "device_id": "iv9a94th6rzt********",
            "datetime": "2020-06-05 17:27:00",
            "latitude": 55.70329032,
            "longitude": 37.65472196,
            "altitude": 427.5,
            "speed": 0,
            "battery_voltage": 23.5,
            "cabin_temperature": 17,
            "fuel_level": null
        }

        {
            "device_id": "rhibbh3y08qm********",
            "datetime": "2020-06-06 09:49:54",
            "latitude": 55.71294467,
            "longitude": 37.66542005,
            "altitude": 429.13,
            "speed": 55.5,
            "battery_voltage": null,
            "cabin_temperature": 18,
            "fuel_level": 32
        }

        {
            "device_id": "iv9a94th6rzt********",
            "datetime": "2020-06-07 15:00:10",
            "latitude": 55.70985913,
            "longitude": 37.62141918,
            "altitude": 417.0,
            "speed": 15.7,
            "battery_voltage": 10.3,
            "cabin_temperature": 17,
            "fuel_level": null
        }
        ```

    1. Send data from the `sample.json` file to the Managed Service for Apache Kafka® source cluster's `sensors` topic using `jq` and `kafkacat`:

        ```bash
        jq -rc . sample.json | kafkacat -P \
           -b <FQDN_of_broker_in_source_cluster>:9091 \
           -t sensors \
           -k key \
           -X security.protocol=SASL_SSL \
           -X sasl.mechanisms=SCRAM-SHA-512 \
           -X sasl.username="<username_in_source_cluster>" \
           -X sasl.password="<user_password_in_source_cluster>" \
           -X ssl.ca.location=/usr/local/share/ca-certificates/Yandex/YandexInternalRootCA.crt -Z
        ```

        The data is sent on behalf of the [created user](#prepare-source). To learn more about setting up an SSL certificate and using `kafkacat`, see [Connecting to an Apache Kafka® cluster from applications](../../managed-kafka/operations/connect/clients.md).

    1. Use `kafkacat` to make sure that the data has been moved from the source cluster to the target Managed Service for Apache Kafka® cluster:

        ```bash
        kafkacat -C \
                 -b <FQDN_of_broker_in_target_cluster>:9091 \
                 -t measurements \
                 -X security.protocol=SASL_SSL \
                 -X sasl.mechanisms=SCRAM-SHA-512 \
                 -X sasl.username="<username_in_target_cluster>" \
                 -X sasl.password="<user_password_in_target_cluster>" \
                 -X ssl.ca.location=/usr/local/share/ca-certificates/Yandex/YandexInternalRootCA.crt -Z -K:
        ```

## Delete the resources you created {#clear-out}

{% note info %}

Before deleting the resources, [deactivate the transfer](../../data-transfer/operations/transfer.md#deactivate).

{% endnote %}


Some resources are not free of charge. Delete the resources you no longer need to avoid paying for them:


{% list tabs group=instructions %}

- Manually {#manual}

  1. [Delete the transfer](../../data-transfer/operations/transfer.md#delete-transfer).
  1. [Delete](../../data-transfer/operations/endpoint/index.md#delete) the source and target endpoints.
  1. [Delete the Managed Service for Apache Kafka® clusters](../../managed-kafka/operations/cluster-delete.md).


- Terraform {#tf}

  1. In the terminal window, go to the directory containing the infrastructure plan.
  
      {% note warning %}
  
      Make sure the directory has no Terraform manifests with the resources you want to keep. Terraform deletes all resources that were created using the manifests in the current directory.
  
      {% endnote %}
  
  1. Delete resources:
  
      1. Run this command:
  
          ```bash
          terraform destroy
          ```
  
      1. Confirm deleting the resources and wait for the operation to complete.
  
      All the resources described in the Terraform manifests will be deleted.


{% endlist %}