YDB change data capture and delivery to Apache Kafka®

You can track data changes in a Managed Service for YDB source and send them to a Managed Service for Apache Kafka® target cluster using Change Data Capture (CDC). This data is automatically added to Managed Service for Apache Kafka® topics with Managed Service for YDB table names.

To run data delivery:

1. Prepare the source.
2. Prepare and activate the transfer.
3. Test the transfer.

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

Getting startedGetting started

1. Prepare the data transfer infrastructure:

   Manually

   Terraform

   1. Create a Managed Service for YDB database in any suitable configuration.

   2. If you selected Dedicated DB mode, create and configure a security group in the network hosting the DB.

   3. Create a Managed Service for Apache Kafka® target cluster in any suitable configuration with publicly available hosts.

   4. If you are using security groups, configure them so that you can connect to the cluster from the internet.

   5. Configure Apache Kafka® topics in the target cluster. The settings vary depending on the topic management method used. Data topic names are generated in this format: <topic_prefix>.<YDB_table_name>. In this tutorial, we will use the cdc prefix as an example.

      • If topics are managed using standard Yandex Cloud interfaces (management console, CLI, or API):

        1. Create a topic named cdc.sensors.

           To track changes in multiple tables, create a separate topic with the cdc prefix for each of them.

        2. Create a user with the ACCESS_ROLE_CONSUMER and ACCESS_ROLE_PRODUCER roles for the cdc.sensors topic. To include all created topics, specify cdc.* in the topic name.

      • If topics are managed using the Kafka Admin API:

        1. Create an admin user.

        2. In addition to ACCESS_ROLE_ADMIN, assign the admin user the ACCESS_ROLE_CONSUMER and ACCESS_ROLE_PRODUCER roles for cdc.* topics whose names begin with the cdc prefix.

           Required topics will be created automatically upon the first change to the source cluster tables you are tracking. This solution can be useful to track changes in multiple tables but requires extra free space in cluster storage. For more information, see Storage in Managed Service for Apache Kafka®.

   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 data-transfer-ydb-mkf.tf configuration file to the same working directory.

      This file describes:

      • Network.
      • Subnet.
      • Security group and the rule required to connect to a Managed Service for Apache Kafka® cluster.
      • Managed Service for YDB database.
      • Managed Service for Apache Kafka® target cluster.
      • Apache Kafka® topic.
      • Apache Kafka® user.
      • Transfer.

      The topic management method is specified in the kf_topics_management Terraform variable. It is set when running the terraform plan and terraform apply commands (see below):

      • If topics are managed using standard Yandex Cloud interfaces (management console, CLI, or API):

        1. To track changes in multiple tables, add the descriptions of the separate topics with the cdc prefix to the configuration file, one for each table.
        2. Set the kf_topics_management Terraform variable to false.

      • If the topics are managed using the Kafka Admin API, set the kf_topics_management Terraform variable to true.

   6. In the data-transfer-ydb-mkf.tf file, specify these variables:

      • source_db_name: Managed Service for YDB database name.
      • target_kf_version: Apache Kafka® version in the target cluster.
      • target_user_name: Username for connection to the Apache Kafka® topic.
      • target_user_password: User password.
      • transfer_enabled: Set to 0 to ensure no transfer is created until you create endpoints manually.

   7. Make sure the Terraform configuration files are correct using this command:

      terraform validate
      

      If there are any errors in the configuration files, Terraform will point them out.

   8. Create the required infrastructure:

      1. Run the command to view planned changes:

         terraform plan
         

         If the resource configuration descriptions are correct, the terminal will display a list of the resources to modify and their parameters. This is a test step. No resources are updated.

      2. If you are happy with the planned changes, apply them:

         1. Run the command:

            terraform apply
            

         2. Confirm the update of 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 kafkacat to read and write data to Apache Kafka® topics.

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

   Check that you can use it to connect to the Managed Service for Apache Kafka® target cluster over SSL.

Prepare the sourcePrepare the source

1. Connect to the Managed Service for YDB database.

2. Create a YDB table. As an example, we will use the sensors table with information collected, let’s say, from car sensors.

   Add the following columns to the table manually:

   Name	Type	Primary key
   device_id	String	Yes
   datetime	String
   latitude	Double
   longitude	Double
   altitude	Double
   speed	Double
   battery_voltage	Double
   cabin_temperature	Uint8
   fuel_level	Uint32

   Leave the default values for other settings.

   You can also create a table with the following YQL command:

   CREATE TABLE sensors (
       device_id String,
       datetime String,
       latitude Double,
       longitude Double,
       altitude Double,
       speed Double,
       battery_voltage Double,
       cabin_temperature Uint8,
       fuel_level Uint32,
       PRIMARY KEY (device_id)
   )
   

Prepare and activate the transferPrepare and activate the transfer

1. Create a source endpoint:

   • Database type: YDB.

   • Endpoint parameters:

     • Connection settings:

       • Database: Select the Managed Service for YDB database from the list.
       • Service account ID: Select or create a service account with the editor role.

     • Included paths list: Specify the names of tables and Managed Service for YDB database directories to transfer.

       Warning

       Only the listed tables and directories will be replicated. If you do not specify any names, no tables will be transferred.

2. Create a target endpoint:

   • Database type: Kafka.

   • Endpoint parameters:

     • Connection type: Managed Service for Apache Kafka cluster.

       • Managed Service for Apache Kafka cluster: Select the previously created Managed Service for Apache Kafka® source cluster.
       • Authentication: Specify the details of the created Apache Kafka® user.

     • Topic: Topic full name.

     • Topic full name: cdc.sensors.

     If you need to track changes in multiple tables, fill out the fields as follows:

     • Topic: Topic prefix.
     • Topic prefix: Enter the cdc prefix you used to generate topic names.

3. Create a transfer:

   Manually

   Terraform

   1. Create a transfer of the Replication type that will use the created endpoints.
   2. Activate your transfer.

   1. In the data-transfer-ydb-mkf.tf file, specify these variables:

      • source_endpoint_id: ID of the source endpoint.
      • target_endpoint_id: Target endpoint ID.
      • transfer_enabled: 1 to create a transfer.

   2. Make sure the Terraform configuration files are correct using this command:

      terraform validate
      

      If there are any errors in the configuration files, Terraform will point them out.

   3. Create the required infrastructure:

      1. Run the command to view planned changes:

         terraform plan
         

         If the resource configuration descriptions are correct, the terminal will display a list of the resources to modify and their parameters. This is a test step. No resources are updated.

      2. If you are happy with the planned changes, apply them:

         1. Run the command:

            terraform apply
            

         2. Confirm the update of resources.

         3. Wait for the operation to complete.

      Once created, your transfer will be activated automatically.

Test the transferTest the transfer

1. Wait for the transfer status to change to Replicating.

2. In a separate terminal, run the kafkacat utility in consumer mode:

   kafkacat \
       -C \
       -b <broker_host_1_FQDN>:9091,...,<broker_host_N_FQDN>:9091 \
       -t cdc.sensors \
       -X security.protocol=SASL_SSL \
       -X sasl.mechanisms=SCRAM-SHA-512 \
       -X sasl.username=kafka-user \
       -X sasl.password=<password> \
       -X ssl.ca.location=/usr/local/share/ca-certificates/Yandex/YandexInternalRootCA.crt \
       -Z \
       -K:
   

   You can obtain the FQDNs of broker hosts with a list of hosts in the Managed Service for Apache Kafka® cluster.

3. Connect to the Managed Service for YDB database and add test data to the sensors table:

   REPLACE INTO sensors (device_id, datetime, latitude, longitude, altitude, speed, battery_voltage, cabin_temperature, fuel_level) VALUES
       ('iv9a94th6rzt********', '2022-06-05 17:27:00', 55.70329032, 37.65472196, 427.5, 0, 23.5, 17, NULL),
       ('rhibbh3y08qm********', '2022-06-06 09:49:54', 55.71294467, 37.66542005, 429.13, 55.5, NULL, 18, 32),
       ('iv9a94th6rzt********', '2022-06-08 17:45:00', 53.70987913, 36.62549834, 378.0, NULL, 20.5, 15, 20);
   

4. Make sure the terminal running the kafkacat utility displays the data format schema of the sensors table and information about the added rows.

   Example of the message fragment

   {
     "payload": {
         "device_id": "aXY5YTk0dGg2cnp0b294********"
       },
       "schema": {
         "fields": [
           {
               "field": "device_id",
               "optional": false,
               "type": "bytes"
           }
         ],
         "name": "cdc..sensors.Key",
         "optional": false,
         "type": "struct"
       }
   }: {
     "payload": {
       "after": {
           "altitude": 378,
           "battery_voltage": 20.5,
           "cabin_temperature": 15,
           "datetime": "MjAyMi0wNi0wOCAxNzo0********",
           "device_id": "aXY5YTk0dGg2cnp0b294********",
           "fuel_level": 20,
           "latitude": 53.70987913,
           "longitude": 36.62549834,
           "speed": null
       },
       "before": null,
       "op": "c",
       "source": {
           "db": "",
           "name": "cdc",
           "snapshot": "false",
           "table": "sensors",
           "ts_ms": 1678642104797,
           "version": "1.1.2.Final"
       },
       "transaction": null,
       "ts_ms": 1678642104797
     },
     "schema": {
       "fields": [
           {
               "field": "before",
               "fields": [
                   {
                       "field": "device_id",
                       "optional": false,
                       "type": "bytes"
                   },
                   ...
               ],
               "name": "cdc..sensors.Value",
               "optional": true,
               "type": "struct"
           },
           {
               "field": "after",
               "fields": [
                   {
                       "field": "device_id",
                       "optional": false,
                       "type": "bytes"
                   },
                   ...
               ],
               "name": "cdc..sensors.Value",
               "optional": true,
               "type": "struct"
           },
           {
               "field": "source",
               "fields": [
                   {
                       "field": "version",
                       "optional": false,
                       "type": "string"
                   },
                   {
                       "field": "connector",
                       "optional": false,
                       "type": "string"
                   },
                   {
                       "field": "name",
                       "optional": false,
                       "type": "string"
                   },
                   {
                       "field": "ts_ms",
                       "optional": false,
                       "type": "int64"
                   },
                   {
                       "default": "false",
                       "field": "snapshot",
                       "name": "io.debezium.data.Enum",
                       "optional": true,
                       "parameters": {
                           "allowed": "true,last,false"
                       },
                       "type": "string",
                       "version": 1
                   },
                   {
                       "field": "db",
                       "optional": false,
                       "type": "string"
                   },
                   {
                       "field": "table",
                       "optional": false,
                       "type": "string"
                   }
               ],
               "optional": false,
               "type": "struct"
           },
           ...,
           {
               "field": "transaction",
               "fields": [
                   {
                       "field": "id",
                       "optional": false,
                       "type": "string"
                   },
                   {
                       "field": "total_order",
                       "optional": false,
                       "type": "int64"
                   },
                   {
                       "field": "data_collection_order",
                       "optional": false,
                       "type": "int64"
                   }
               ],
               "optional": true,
               "type": "struct"
           }
       ],
       "name": "cdc..sensors.Envelope",
       "optional": false,
       "type": "struct"
     }
   }
   

Delete the resources you createdDelete the resources you created

Some resources are not free of charge. To avoid paying for them, delete the resources you no longer need:

1. Delete the transfer.
2. Delete endpoints for both the source and target.
3. If you created a service account together with the source endpoint, delete it.

Delete the other resources depending on how they were created: