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Yandex Managed Service for Apache Kafka®

Delivering data from Yandex Managed Service for PostgreSQL using Debezium

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You can track data changes in Managed Service for PostgreSQL and send them to Managed Service for Apache Kafka® using Change Data Capture (CDC).

In this article, you will learn how to create a virtual machine in Yandex Cloud and set up Debezium, software used for CDC.

Before you begin

  1. Create a source cluster with the following settings:

    • With publicly available hosts.
    • With the db1 database.
    • With the user1 user.

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

  3. Create a virtual machine with Ubuntu 20.04 and a public IP address.

  4. Set up security groups so that you can connect to clusters from the internet and created VM, and connect to this VM over SSH from the internet:

  5. Connect to a virtual machine over SSH and perform preliminary setup:

    1. Install the dependencies:

      sudo apt update && \
    sudo apt install kafkacat openjdk-17-jre postgresql-client --yes

    2. Create a folder for Apache Kafka®:

      sudo mkdir -p /opt/kafka/

    3. Download and unpack the archive with Apache Kafka® executable files in this folder. For example, to download and unpack Apache Kafka® 3.0, run the command:

      wget https://archive.apache.org/dist/kafka/3.0.0/kafka_2.13-3.0.0.tgz && \
sudo tar xf kafka_2.13-3.0.0.tgz --strip 1 --directory /opt/kafka/

      You can check the current Apache Kafka® version on the page with project downloads.

    4. Install certificates on the VM and check the availability of clusters:

    5. Create a folder that will store the files required for the operation of the Debezium connector:

      sudo mkdir -p /etc/debezium/plugins/

    6. The Debezium connector can connect to Managed Service for Apache Kafka® broker hosts if an SSL certificate is added to Java secure storage (Java Key Store). For added storage security, add a password that is at least 6 characters long to the -storepass parameter:

      sudo keytool \
    -importcert \
    -alias YandexCA -file /usr/local/share/ca-certificates/Yandex/YandexCA.crt \
    -keystore /etc/debezium/keystore.jks \
    -storepass <JKS password> \
    --noprompt

Preparing the source cluster

  1. Assign to the user user1 the role mdb_replication.

    This is necessary to create a publication for Debezium to monitor changes in a Managed Service for PostgreSQL cluster.

  2. Connect to the db1 database on behalf of user1.

  3. Add test data to the database. In this example, a simple table with information from car sensors is used.

    Create a table:

    CREATE TABLE public.measurements (
    "device_id" text PRIMARY KEY NOT NULL,
    "datetime" timestamp NOT NULL,
    "latitude" real NOT NULL,
    "longitude" real NOT NULL,
    "altitude" real NOT NULL,
    "speed" real NOT NULL,
    "battery_voltage" real,
    "cabin_temperature" real NOT NULL,
    "fuel_level" real
);

    Populate the table with data:

    INSERT INTO public.measurements VALUES
    ('iv9a94th6rztooxh5ur2', '2020-06-05 17:27:00', 55.70329032, 37.65472196,  427.5,    0, 23.5, 17, NULL),
    ('rhibbh3y08qmz3sdbrbu', '2020-06-06 09:49:54', 55.71294467, 37.66542005, 429.13, 55.5, NULL, 18, 32),
    ('iv9a94th678tooxh5ur2', '2020-06-07 15:00:10', 55.70985913, 37.62141918,  417.0, 15.7, 10.3, 17, NULL);

  4. Create a publication for the table:

    CREATE PUBLICATION mpg_publication FOR TABLE public.measurements;

Configure Debezium

  1. Connect to the virtual machine over SSH.

  2. Download and unpack a proper Debezium connector to the folder /etc/debezium/plugins/.

    You can check the current connector version on the project page. The commands for version 1.9.4.Final are below.

    VERSION="1.9.4.Final"
wget https://repo1.maven.org/maven2/io/debezium/debezium-connector-postgres/${VERSION}/debezium-connector-postgres-${VERSION}-plugin.tar.gz && \
sudo tar -xzvf debezium-connector-postgres-${VERSION}-plugin.tar.gz -C /etc/debezium/plugins/

  3. Create the file /etc/debezium/mdb-connector.conf with Debezium connector settings for connecting to the source cluster:

    name=debezium-mpg
connector.class=io.debezium.connector.postgresql.PostgresConnector
plugin.name=pgoutput
database.hostname=c-<cluster ID>.rw.mdb.yandexcloud.net
database.port=6432
database.user=user1
database.password=<user1 password>
database.dbname=db1
database.server.name=mpg
table.include.list=public.measurements
publication.name=mpg_publication
slot.name=debezium_slot
heartbeat.interval.ms=15000
heartbeat.topics.prefix=__debezium-heartbeat

    Where:

    • name: Logical name of the Debezium connector. Used for the connector's internal needs.

    • database.hostname: A special FQDN to connect to the source cluster master host.

      You can get the cluster ID with a list of clusters in the folder.

    • database.user: The PostgreSQL username.

    • database.dbname: The PostgreSQL database name.

    • database.server.name: Name of the database server that Debezium will use when choosing a topic for sending messages.

    • table.include.list: Names of tables for which Debezium should track changes. Specify full names that include the schema name (default: public). Debezium will use values from this field when selecting a topic for sending messages.

    • publication.name: The name of the publication created on the source cluster.

    • slot.name: The name of the replication slot that will be created by Debezium when working with the publication.

    • heartbeat.interval.ms and heartbeat.topics.prefix: The heartbeat settings needed for Debezium.

Prepare the target cluster

  1. Create a topic to store data from the source cluster:

    • Name: mpg.public.measurements.

      The following conventions are used for topic names: <server name>.<schema name>.<table name>.

      According to the Debezium configuration file:

      • The name of the mpg server is specified in the database.server.name parameter.
      • The name of the public schema is specified together with the name of the measurements table in the table.include.list parameter.

    If you need to track data changes in multiple tables, create a separate topic for each of them.

  2. Create a service topic to track the connector status:

    • Name: __debezium-heartbeat.mpg.

      Names for service topics follow the convention <prefix for heartbeat>.<server name>.

      According to the Debezium configuration file:

      • The __debezium-heartbeat prefix is specified in the heartbeat.topics.prefix parameter.
      • The name of the mpg server is specified in the database.server.name parameter.

    • Cleanup policy: Compact.

    If you need data from multiple source clusters, create a separate service topic for each of them.

  3. Create a user named debezium.

  4. Grant to the debezium user the rights ACCESS_ROLE_CONSUMER and ACCESS_ROLE_PRODUCER to the created topics.

Start Debezium

  1. Create a file with Debezium worker settings:

    /etc/debezium/worker.conf

    # AdminAPI connect properties
bootstrap.servers=<FQDN of broker host 1>:9091,...,<FQDN of broker host N>:9091
sasl.mechanism=SCRAM-SHA-512
security.protocol=SASL_SSL
ssl.truststore.location=/etc/debezium/keystore.jks
ssl.truststore.password=<JKS password>
sasl.jaas.config=org.apache.kafka.common.security.scram.ScramLoginModule required username="debezium" password="<debezium user password>";

# Producer connect properties
producer.sasl.mechanism=SCRAM-SHA-512
producer.security.protocol=SASL_SSL
producer.ssl.truststore.location=/etc/debezium/keystore.jks
producer.ssl.truststore.password=<JKS password>
producer.sasl.jaas.config=org.apache.kafka.common.security.scram.ScramLoginModule required username="debezium" password="<debezium user password>";

# Worker properties
plugin.path=/etc/debezium/plugins/
key.converter=org.apache.kafka.connect.json.JsonConverter
value.converter=org.apache.kafka.connect.json.JsonConverter
key.converter.schemas.enable=true
value.converter.schemas.enable=true
offset.storage.file.filename=/etc/debezium/worker.offset

  2. In a separate terminal, start the connector:

    sudo /opt/kafka/bin/connect-standalone.sh \
    /etc/debezium/worker.conf \
    /etc/debezium/mdb-connector.conf

Check the health of Debezium

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

    kafkacat \
    -C \
    -b <FQDN of broker host 1>:9091,...,<FQDN of broker host N>:9091 \
    -t mpg.db1.measurements \
    -X security.protocol=SASL_SSL \
    -X sasl.mechanisms=SCRAM-SHA-512 \
    -X sasl.username=debezium \
    -X sasl.password=<password> \
    -X ssl.ca.location=/usr/local/share/ca-certificates/Yandex/YandexCA.crt \
    -Z \
    -K:

    The data format schema of the db1.public.measurements table and the information about the previously added rows will be printed.

    Example of the message fragment
    {
"schema": {
    ...
},
"payload": {
    "before": null,
    "after": {
        "device_id": "iv9a94th6rztooxh5ur2",
        "datetime": 1591378020000000,
        "latitude": 55.70329,
        "longitude": 37.65472,
        "altitude": 427.5,
        "speed": 0.0,
        "battery_voltage": 23.5,
        "cabin_temperature": 17.0,
        "fuel_level": null
    },
    "source": {
        "version": "1.8.1.Final",
        "connector": "postgresql",
        "name": "mpg",
        "ts_ms": 1628245046882,
        "snapshot": "true",
        "db": "db1",
        "sequence": "[null,\"4328525512\"]",
        "schema": "public",
        "table": "measurements",
        "txId": 8861,
        "lsn": 4328525328,
        "xmin": null
    },
    "op": "r",
    "ts_ms": 1628245046893,
    "transaction": null
  }
}

  2. Connect to the source cluster and add another row to the measurements table:

    INSERT INTO public.measurements VALUES ('iv7b74th678tooxh5ur2', '2020-06-08 17:45:00', 53.70987913, 36.62549834, 378.0, 20.5, 5.3, 20, NULL);

  3. Make sure the terminal running kafkacat displays details about the added row.

Delete the resources you created

If you no longer need these resources, delete them:

  1. Delete the virtual machine.

    If you reserved a public static IP address for the virtual machine, release and delete it.

  2. Delete the clusters:

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