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Debezium-Kafka Hazelcast Connector

This bundle integrates Hazelcast with Debezium for ingesting initial data and CDC records from MySQL into a Hazelcast cluster via a Kafka sink connector included in the padogrid distribution. It supports inserts, updates and deletes.

Installing Bundle

This bundle supports Hazelcast 3.12.x, 4.x, 5.x.

install_bundle -download bundle-hazelcast-3n4n5-docker-debezium_kafka

❗️ If you are running this demo on WSL, make sure your workspace is on a shared folder. The Docker volume it creates will not be visible otherwise.

Use Case

This use case ingests data changes made in the MySQL database into a Hazelcast cluster via Kafka connectors: the Debezium MySQL source connector and the hazelcast-addon Debezium sink connector.

Required Software

• Docker
• Maven 3.x
• Hazelcast 3.12.x, 4.x, or 5.x

Optional Software

• jq

Debezium Tutorial

The demo follows the Debezium Tutorial steps shown in the link below.

https://debezium.io/documentation/reference/2.3/tutorial.html#registering-connector-monitor-inventory-database

All the commands provided in the tutorial are wrapped in the scripts found in the bin_sh directory. We'll use these scripts to simplify the demo.

Building Demo

✏️ This bundle builds the demo enviroment based on the Hazelcast and Management versions in your workspace. Make sure your workspace has been configured with the desired versions before building the demo environment.

First, change your cluster context to a Hazelcast cluster. This is required in order to configure the Hazelcast Docker containers.

Terminal Hazelcast

# Create a Hazelcast cluster if it does not already exist.
create_cluster -product hazelcast

# Switch context
switch_cluster myhz

Now, build the demo by running the build_app command as shown below. This command compiles and packages the VersionedPortable data (domain) classes found in the source directory src. It also copies the Hazelcast and hazelcast-addon-core jar files to the Docker container mounted volume in the padogrid directory so that the Hazelcast Debezium Kafka connector can include them in its class path.

Terminal Hazelcast

cd_docker debezium_kafka/bin_sh
./build_app

Upon successful build, the padogrid directory should have jar files similar to the following:

Terminal Hazelcast

cd_docker debezium_kafka
tree padogrid

padogrid
├── etc
│   └── hazelcast-client.xml
├── lib
│   ├── hazelcast-addon-common-1.0.0.jar
│   ├── hazelcast-addon-core-5-1.0.0.jar
│   ├── hazelcast-enterprise-5.3.6.jar
│   └── padogrid-common-1.0.0.jar
├── log
└── plugins
    ├── hazelcast-addon-core-5-1.0.0-tests.jar
    └── hazelcast-addon-debezium_kafka-1.0.0.jar

Creating my_network

Let's create the my_network network to which all containers will join.

Terminal Hazelcast

docker network create my_network

Creating Hazelcast Docker Containers

Let's create a Hazelcast cluster to run on Docker containers with the my_network network we created in the previous section.

Terminal Hazelcast

create_docker -product hazelcast -cluster hazelcast -network my_network
cd_docker hazelcast

Configuring Hazelcast Cluster

If you will be querying Hazelcast, then you must register the VersionedPortable factory class we have built in the previous section. For example, you can use the desktop app to query and browse the data in the Hazelcast cluster. You can skip this section if you won't be querying data.

Edit hazelcast.xml and register the portable factory class as shown below.

Terminal Hazelcast

cd_docker hazelcast
vi padogrid/etc/hazelcast.xml

<hazelcast ...>
   ...
   <serialization>
      ...
      <portable-factory factory-id="20001">
      org.hazelcast.addon.demo.debezium.data.PortableFactoryImpl
      </portable-factory>
      ...
   </serialization>
   ...
</hazelcast>

Copy the demo data jar file into the plugins directory as follows.

Terminal Hazelcast

cd_docker hazelcast
cp $PADOGRID_WORKSPACE/docker/debezium_kafka/padogrid/plugins/hazelcast-addon-debezium_kafka-1.0.0.jar padogrid/plugins/

Starting Docker Containers

There are numerous Docker containers to this demo. We'll first start the Hazelcast cluster containers and then proceed with the Debezium containers. By default, the scripts provided run the containers in the foreground so that you can view the log events. You will need to launch a total of eight (8) terminals. If you have a screen splitter such as Windows Terminal, it will make things easier.

You can also run some of the scripts in the background by including the -d option. These scripts are mentioned below.

Start Hazelcast Containers

Start the hazelcast Hazelcast cluster containers.

Terminal Hazelcast

cd_docker hazelcast
docker compose up

Start Debezium Containers

Terminal 1-6

Launch six (6) terminals and run each script from their own terminal as shown below. Each script must be run from their own terminal as they will block and display log messages.

cd_docker debezium_kafka/bin_sh

# 1. Start Zookeeper (include '-d' to run it in the background)
./start_zookeeper

# 2. Start Kafka (include '-d' to run it in the background)
./start_kafka

# 3. Start MySQL database (include '-d' to run it in the background)
./start_mysql

# 4. Start Kafka Connect (include '-d' to run it in the background)
./start_kafka_connect

# 5. Start topic watcher
./watch_topic_customers

# 6. Start MySQL CLI
./start_mysql_cli

View Management Center

URL: http://localhost:8080/hazelcast-mancenter

If the managenment center prompts for adding a cluster config then make sure to enter the following.

Cluster Name: dev
Cluster Config State: Enabled
Member Addresses: localhost (or your host os address)

Register Kafka Connect via REST API

There are two (2) Kafka connectors that we must register. The MySQL connector is provided by Debezium and the Hazelcast connector is part of the PadoGrid distribution.

Terminal Driver

cd_docker debezium_kafka/bin_sh
./register_mysql_connector
./register_debezium_hazelcast_connector

Check Kafka Connect

Terminal Driver

# Check status
curl -Ss -H "Accept:application/json" localhost:8083/ | jq

# List registered connectors 
curl -Ss -H "Accept:application/json" localhost:8083/connectors/ | jq

The last command should display the inventory connector that we registered previously.

[
  "debezium-hazelcast-sink",
  "inventory-connector"
]

MySQL CLI

Using the MySQL CLI, you can change table contents. The changes you make will be captured in the form of change events by the Debezium source connector. The Hazelcast sink connector in turn receives the change events, transforms them into data objects and updates (or deletes) the assigned map, i.e., inventory/customers.

Terminal 6

use inventory;
SELECT * FROM customers;
UPDATE customers SET first_name='Anne Marie' WHERE id=1004;
-- Delete - First, delete the row in addresses that references the foreign key
DELETE FROM addresses WHERE customer_id=1004;
DELETE FROM customers WHERE id=1004;

INSERT INTO customers VALUES (default, "Sarah", "Thompson", "kitt@acme.com");
INSERT INTO customers VALUES (default, "Kenneth", "Anderson", "kander@acme.com");

View Map Contents

To view the map contents, run the read_cache command as follows:

Terminal Driver

./read_cache inventory/customers

Output:

Map Values [inventory/customers]:
        [email=gbailey@foobar.com, firstName=George, id=1002, lastName=Bailey]
        [email=sally.thomas@acme.com, firstName=Sally, id=1001, lastName=Thomas]
        [email=ed@walker.com, firstName=Edward, id=1003, lastName=Walker]
        [email=annek@noanswer.org, firstName=Anne Marie, id=1004, lastName=Kretchmar]

Desktop

Optionally, you can also install the desktop app and query the map contents.

Terminal Driver

create_app -product hazelcast -app desktop

To use the destkop, we need to add the demo data jar file in its class path and set the PortableFactory class ID. By default, the workspace's plugins directory is in the desktop class path. Let's place the demo jar file there.

Terminal Driver

cp $PADOGRID_WORKSPACE/docker/debezium_kafka/padogrid/plugins/hazelcast-addon-debezium_kafka-1.0.0.jar $PADOGRID_WORKSPACE/plugins/

Edit the pado.properties file and enter the PortableFactoryImpl class as follows. The PortableFactory class ID is `20001.

Terminal Driver

cd_app desktop
vi etc/pado.properties

etc/pado.properties File:

hazelcast.client.config.serialization.portable.factories=1:org.hazelcast.demo.nw.data.PortableFactoryImpl,\
10000:org.hazelcast.addon.hql.impl.PortableFactoryImpl,\
20001:org.hazelcast.addon.demo.debezium.data.PortableFactoryImpl

Run the desktop.

Terminal Driver

cd_app desktop/bin_sh
./desktop

Teardown

Terminal Driver

# Shutdown Debezium containers
cd_docker debezium_kafka/bin_sh
./cleanup

# Shutdown Hazelcast containers
cd_docker hazelcast
docker compose down

# Remove my_network
docker network rm my_network

# Prune all stopped containers 
docker container prune

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