[Yandex Cloud documentation](../../index.md) > [Yandex Managed Service for PostgreSQL](../index.md) > [Tutorials](index.md) > Delivering data from Yandex Managed Service for Apache Kafka® using Yandex Data Transfer

# Delivering data from Yandex Managed Service for Apache Kafka® using Yandex Data Transfer

# Delivering data from an Apache Kafka® queue to PostgreSQL using Yandex Data Transfer


You can set up data transfer from a Managed Service for Apache Kafka® topic to Managed Service for PostgreSQL using Yandex Data Transfer. Proceed as follows:

1. [Prepare your test data](#prepare-data).
1. [Prepare and activate the 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® cluster, which includes computing resources allocated to hosts, as well as the storage and backup size (see [Managed Service for Apache Kafka® pricing](../../managed-kafka/pricing.md)).
* Managed Service for PostgreSQL cluster, which includes computing resources allocated to hosts, storage and backup size (see [Managed Service for PostgreSQL pricing](../pricing.md)).
* Public IP addresses if public access is enabled for cluster hosts (see [Virtual Private Cloud pricing](../../vpc/pricing.md)).


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

1. Set up your infrastructure:

    {% list tabs group=instructions %}

    - Manually {#manual}

        {% 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. [Create a Managed Service for Apache Kafka® source cluster](../../managed-kafka/operations/cluster-create.md#create-cluster) in any [availability zone](../../overview/concepts/geo-scope.md) with any suitable configuration and public access.

        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) named `mkf-user` with the `ACCESS_ROLE_PRODUCER` and `ACCESS_ROLE_CONSUMER` access permissions for the new topic.

        1. In the same availability zone, [create a Managed Service for PostgreSQL target cluster](../operations/cluster-create.md#create-cluster) of any suitable configuration with `pg-user` as admin and publicly accessible hosts.

        1. Make sure the cluster security groups are configured correctly and allow inbound cluster connections:
            * [Managed Service for Apache Kafka®](../../managed-kafka/operations/connect/index.md#configuring-security-groups).
            * [Managed Service for PostgreSQL](../operations/connect/index.md#configuring-security-groups).

    - Terraform {#tf}

        1. If you do not have Terraform yet, [install it](../../tutorials/infrastructure-management/terraform-quickstart.md#install-terraform).
        1. [Get the authentication credentials](../../tutorials/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](../../tutorials/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](../../tutorials/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 [kafka-postgresql.tf](https://github.com/yandex-cloud-examples/yc-data-transfer-from-kafka-to-postgresql/blob/main/kafka-postgresql.tf) configuration file to the same working directory.

            This file describes:

            * [Networks](../../vpc/concepts/network.md#network) and [subnets](../../vpc/concepts/network.md#subnet) that will host your clusters.
            * [Security groups](../../vpc/concepts/security-groups.md) for cluster access.
            * Managed Service for Apache Kafka® source cluster.
            * Managed Service for PostgreSQL target cluster.
            * Source endpoint.
            * Target endpoint.
            * Transfer.

        1. In `kafka-postgresql.tf`, specify the following:

            * Apache Kafka® and PostgreSQL versions.
            * Apache Kafka® and PostgreSQL user passwords.

        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 %}

1. Install the following 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 your test data {#prepare-data}

Suppose the Apache Kafka® `sensors` topic in the source cluster receives JSON-formatted data from car sensors.

On your local machine, create a `sample.json` file with the following test data:

{% cut "sample.json" %}

```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
}
```

{% endcut %}

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

{% list tabs group=instructions %}

- Manually {#manual}

    1. [Create a source endpoint](../../data-transfer/operations/endpoint/source/kafka.md) of the `Apache Kafka®` type and specify the following for it:

        * **Topic full name**: `sensors`.
        * `json` conversion rules. In the **Data scheme** field, select `JSON specification`, copy the following field specification, and paste it into the form that opens:

        {% cut "sensors-specification" %}

        ```json
        [
            {
                "name": "device_id",
                "type": "utf8",
                "key": true
            },
            {
                "name": "datetime",
                "type": "utf8"
            },
            {
                "name": "latitude",
                "type": "double"
            },
            {
                "name": "longitude",
                "type": "double"
            },
            {
                "name": "altitude",
                "type": "double"
            },
            {
                "name": "speed",
                "type": "double"
            },
            {
                "name": "battery_voltage",
                "type": "double"
            },
            {
                "name": "cabin_temperature",
                "type": "uint16"
            },
            {
                "name": "fuel_level",
                "type": "uint16"
            }
        ]
        ```

        {% endcut %}

    1. [Create a `PostgreSQL` target endpoint](../../data-transfer/operations/endpoint/target/postgresql.md) with these cluster connection settings:

        * **Installation type**: `Managed Service for PostgreSQL cluster`.
        * **Managed Service for PostgreSQL cluster**: `<target_PostgreSQL_cluster_name>` from the drop-down list.
        * **Database**: `db1`.
        * **User**: `pg-user`.
        * **Password**: `<user_password>`.

    1. [Create a transfer](../../data-transfer/operations/transfer.md#create) of the **_Replication_**-type that will use the endpoints you created.
    1. [Activate the transfer](../../data-transfer/operations/transfer.md#activate) and wait for its status to change to **Replicating**.

- Terraform {#tf}

    1. In the `kafka-postgresql.tf` file, set the `transfer_enabled` variable to `1` to create your endpoints and 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.

    1. The transfer will be activated automatically. Wait for its status to change to **Replicating**.

{% endlist %}

## Test the transfer {#verify-transfer}

Make sure data from the Managed Service for Apache Kafka® source cluster topic is being transferred to the Managed Service for PostgreSQL database:

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

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

    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. Make sure the data from the source Managed Service for Apache Kafka® cluster has been transferred to the Managed Service for PostgreSQL database:

    1. [Connect to the Managed Service for PostgreSQL database](../operations/connect/index.md).
    1. Check that the `sensors` table contains the data that was sent:

        ```sql
        SELECT * FROM sensors;
        ```

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

{% note info %}

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

{% endnote %}

To reduce the consumption of resources, delete those you do not need:

{% list tabs group=instructions %}

- Manually {#manual}

    1. [Delete the transfer](../../data-transfer/operations/transfer.md#delete).
    1. [Delete the endpoints](../../data-transfer/operations/endpoint/index.md#delete).
    1. [Delete the Managed Service for Apache Kafka® cluster](../../managed-kafka/operations/cluster-delete.md).
    1. [Delete the Managed Service for PostgreSQL cluster](../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 %}
```