Delivering data from an Apache Kafka® queue to PostgreSQL

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 the test data.
2. Set up and activate the transfer.
3. Test your transfer.

If you no longer need the resources you created, delete them.

Required paid resourcesRequired paid resources

• Managed Service for Apache Kafka® cluster: Computing resources allocated to hosts, storage and backup size (see Managed Service for Apache Kafka® pricing).
• Managed Service for PostgreSQL cluster: Computing resources allocated to hosts, storage and backup size (see Managed Service for PostgreSQL pricing).
• Public IP addresses if public access is enabled for cluster hosts (see Virtual Private Cloud pricing).

Getting startedGetting started

1. Set up the infrastructure:

   Manually

   Terraform

   1. Create a Managed Service for Apache Kafka® source cluster in any availability zone with any suitable configuration and public access.

   2. In the source cluster, create a topic named sensors.

   3. In the source cluster, create a user named mkf-user with the ACCESS_ROLE_PRODUCER and ACCESS_ROLE_CONSUMER access permissions for the topic.

   4. In the same availability zone, create a Managed Service for PostgreSQL target cluster in any appropriate configuration with pg-user as the admin user and publicly available hosts.

   5. Make sure the cluster security groups are properly configured and allow inbound cluster connections:

      • Managed Service for Apache Kafka®.
      • Managed Service for PostgreSQL.

   1. If you do not have Terraform yet, install it.

   2. Get the authentication credentials. You can add them to environment variables or specify them later in the provider configuration file.

   3. Configure and initialize a provider. There is no need to create a provider configuration file manually, you can download it.

   4. Place the configuration file in a separate working directory and specify the parameter values. If you did not add the authentication credentials to environment variables, specify them in the configuration file.

   5. Download the kafka-postgresql.tf configuration file to the same working directory.

      This file describes:

      • Networks and subnets where your clusters will be hosted.
      • Security groups for cluster access.
      • Managed Service for Apache Kafka® source cluster.
      • Managed Service for PostgreSQL target cluster.
      • Target endpoint.
      • Transfer.

   6. In the kafka-postgresql.tf file, specify the following:

      • Apache Kafka® and PostgreSQL versions
      • Apache Kafka® and PostgreSQL user passwords

   7. Validate your Terraform configuration files using this command:

      terraform validate
      

      Terraform will display any configuration errors detected in your files.

   8. Create the required infrastructure:

      1. Run this command to view the planned changes:

         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.

      2. If everything looks correct, apply the changes:

         1. Run this command:

            terraform apply
            

         2. Confirm updating the resources.

         3. 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.

2. Install the following tools:

   • kafkacat: For reading from and writing to Apache Kafka® topics.

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

     Make sure you can use it to connect to the Managed Service for Apache Kafka® source cluster over SSL.

   • jq: For stream processing of JSON files.

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

Prepare your test dataPrepare your test data

Let's assume the Apache Kafka® sensors topic in the source cluster receives data from car sensors in JSON format.

Create a local sample.json file with the following test data:

{
    "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
}

Set up and activate the transferSet up and activate the transfer

1. Create a source endpoint with the Apache Kafka® type and specify the following items for it:

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

   [
       {
           "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"
       }
   ]
   

2. Create a target endpoint and set up the transfer:

   Manually

   Terraform

   1. Create a target endpoint of the PostgreSQL type and specify the cluster connection settings in it:

      • 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>.

   2. Create a Replication-type transfer configured to use the new endpoints.

   3. Activate the transfer and wait for its status to change to Replicating.

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

      • kf_source_endpoint_id: Source endpoint ID.
      • transfer_enabled: 1 to create a target endpoint and a transfer.

   2. Validate your Terraform configuration files using this command:

      terraform validate
      

      Terraform will display any configuration errors detected in your files.

   3. Create the required infrastructure:

      1. Run this command to view the planned changes:

         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.

      2. If everything looks correct, apply the changes:

         1. Run this command:

            terraform apply
            

         2. Confirm updating the resources.

         3. Wait for the operation to complete.

   4. The transfer will activate automatically upon creation. Wait for its status to change to Replicating.

Test your transferTest your transfer

Make sure that the data from the topic in the source Managed Service for Apache Kafka® cluster 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:

   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="<source_cluster_user_password>" \
       -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 a Apache Kafka® cluster from applications.

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

   1. Connect to the Managed Service for PostgreSQL database.

   2. Check that the sensors table contains the data that was sent:

      SELECT * FROM sensors;
      

Delete the resources you createdDelete the resources you created

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

1. Delete the transfer.

2. Delete the source endpoint.

3. Delete other resources using the same method used for their creation:

   Manually

   Terraform

   1. Delete the target endpoint.
   2. Delete the Managed Service for Apache Kafka® cluster.
   3. Delete the Managed Service for PostgreSQL cluster.

   1. In the terminal window, go to the directory containing the infrastructure plan.

      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.

   2. Delete resources:

      1. Run this command:

         terraform destroy
         

      2. Confirm deleting the resources and wait for the operation to complete.

      All the resources described in the Terraform manifests will be deleted.