Chapter 2. Installing Debezium connectors on RHEL Install Debezium connectors through Streams for Apache Kafka by extending Kafka Connect with connector plugins. Following a deployment of Streams for Apache Kafka, you can deploy Debezium as a connector configuration through Kafka Connect. 2.1. Kafka topic creation recommendations Debezium stores data in multiple Apache Kafka topics. The topics must either be created in advance by an administrator, or you can configure Kafka Connect to configure topics automatically . The following list describes limitations and recommendations to consider when creating topics: Database schema history topics for the Debezium Db2, MySQL, Oracle, and SQL Server connectors For each of the preceding connectors a database schema history topic is required. Whether you manually create the database schema history topic, use the Kafka broker to create the topic automatically, or use Kafka Connect to create the topic , ensure that the topic is configured with the following settings: Infinite or very long retention. Replication factor of at least three in production environments. Single partition. Other topics When you enable Kafka log compaction so that only the last change event for a given record is saved, set the following topic properties in Apache Kafka: min.compaction.lag.ms delete.retention.ms To ensure that topic consumers have enough time to receive all events and delete markers, specify values for the preceding properties that are larger than the maximum downtime that you expect for your sink connectors. For example, consider the downtime that might occur when you apply updates to sink connectors. Replicated in production. Single partition. You can relax the single partition rule, but your application must handle out-of-order events for different rows in the database. Events for a single row are still totally ordered. If you use multiple partitions, the default behavior is that Kafka determines the partition by hashing the key. Other partition strategies require the use of single message transformations (SMTs) to set the partition number for each record. 2.2. Planning the Debezium connector configuration Before you deploy a Debezium connector, determine how you want to configure the connector. The configuration provides information that specifies the behavior of the connector and enables Debezium to connect to the source database. You specify the connector configuration as JSON, and when you are ready to register the connector, you use curl to submit the configuration to the Kafka Connect API endpoint. Prerequisites A source database is deployed and the Debezium connector can access the database. You know the following information, which the connector requires to access the source database: Name or IP address of the database host. Port number for connecting to the database. Name of the account that the connector can use to sign in to the database. Password of the database user account. Name of the database. The names of the tables from which you want the connector to capture information. The name of the Kafka broker to which you want the connector to emit change events. The name of the Kafka topic to which you want the connector to send database history information. Procedure Specify the configuration that you want to apply to the Debezium connector in JSON format. The following example shows a simple configuration for a Debezium MySQL connector: { "name": "inventory-connector", 1 "config": { "connector.class": "io.debezium.connector.mysql.MySqlConnector", 2 "tasks.max": "1", 3 "database.hostname": "mysql", 4 "database.port": "3306", 5 "database.user": "debezium", 6 "database.password": "dbz", 7 "database.server.id": "184054", 8 "topic.prefix": "dbserver1", 9 "table.include.list": "public.inventory", 10 "schema.history.internal.kafka.bootstrap.servers": "kafka:9092", 11 "schema.history.internal.kafka.topic": "dbhistory.inventory" 12 } } 1 The name of the connector to register with the Kafka Connect cluster. 2 The name of the connector class. 3 The number of tasks that can operate concurrently. Only one task should operate at a time. 4 The host name or IP address of the host database instance. 5 The port number of the database instance. 6 The name of the user account through which Debezium connects to the database. 7 The password for the database user account. 8 A unique numeric ID for the connector. This property is used for the MySQL connector only. 9 A string that serves as the logical identifier for the database server or cluster of servers from which the connector captures changes. The specified string designates a namespace. Debezium prefixes this name to each Kafka topic that the connector writes to, as well as to the names of Kafka Connect schemas, and the namespaces of the corresponding Avro schema, when the Avro converter is used. 10 The list of tables from which the connector captures change events. 11 The name of the Kafka broker where the connector sends the database schema history. The specified broker also receives the change events that the connector emits. 12 The name of the Kafka topic that stores the schema history. After a connector restart, the connector resumes reading the database log from the point at which it stopped, emitting events for any transactions that occurred while it was offline. Before the connector writes change events for an unread transaction to Kafka, it checks the schema history and then applies the schema that was in effect when the original transaction occurred. Additional information For information about the configuration properties that you can set for each type of connector, see the deployment documentation for the connector in the Debezium User Guide . steps Section 2.3, "Deploying Debezium with Streams for Apache Kafka on Red Hat Enterprise Linux" . 2.3. Deploying Debezium with Streams for Apache Kafka on Red Hat Enterprise Linux This procedure describes how to set up connectors for Debezium on Red Hat Enterprise Linux. Connectors are deployed to an Streams for Apache Kafka cluster using Apache Kafka Connect, a framework for streaming data between Apache Kafka and external systems. Kafka Connect must be run in distributed mode rather than standalone mode. Prerequisites The host environment to which you want to deploy Debezium runs Red Hat Enterprise Linux, AMQ Streams, and Java in a supported configuration . For information about how to install Streams for Apache Kafka, see Using Streams for Apache Kafka on RHEL with ZooKeeper . For information about how to install a basic, non-production Streams for Apache Kafka cluster that contains a single ZooKeeper node, and a single Kafka node, see Running a single node Kafka cluster in Using Streams for Apache Kafka on RHEL with ZooKeeper. Note If you are running an earlier version of AMQ Streams, you must first upgrade to Streams for Apache Kafka 2.7. For information about the upgrade process, see Streams for Apache Kafka and Kafka upgrades . You have administrative privileges ( sudo access) on the host. Apache ZooKeeper and the Apache Kafka broker are running. Kafka Connect is running in distributed mode , and not in standalone mode. You know the credentials of the kafka user that was created when Streams for Apache Kafka was installed. A source database is deployed and the host where you deploy Debezium has access to the database. You know how you want to configure the connector . Procedure Download the Debezium connector or connectors that you want to use from the Software Downloads site. For example, to use Debezium with a MySQL database, download the Debezium 2.7.3 MySQL Connector . On the Red Hat Enterprise Linux host where you deployed Streams for Apache Kafka, open a terminal window and create a connector-plugins directory in /opt/kafka , if it does not already exist: USD sudo mkdir /opt/kafka/connector-plugins Enter the following command to extract the contents of the Debezium connector archive that you downloaded to the /opt/kafka/connector-plugins directory. USD sudo unzip debezium-connector-mysql-2.7.3.Final.zip -d /opt/kafka/connector-plugins Repeat Steps 1 -3 for each connector that you want to install. From a terminal window, sign in as the kafka user: USD su - kafka USD Password: Stop the Kafka Connect process if it is running. Check whether Kafka Connect is running in distributed mode by entering the following command: USD jcmd | grep ConnectDistributed If the process is running, the command returns the process ID, for example: Stop the process by entering the kill command with the process ID, for example, USD kill 18514 Edit the connect-distributed.properties file in /opt/kafka/config/ and set the value of plugin.path to the location of the parent directory for the Debezium connector plug-ins: plugin.path=/opt/kafka/connector-plugins Start Kafka Connect in distributed mode. USD /opt/kafka/bin/connect-distributed.sh /opt/kafka/config/connect-distributed.properties After Kafka Connect is running, use the Kafka Connect API to register the connector. Enter a curl command to submit a POST request that sends the connector configuration JSON that you specified in Section 2.2, "Planning the Debezium connector configuration" to the Kafka Connect REST API endpoint at localhost:8083/connectors . For example: curl -i -X POST -H "Accept:application/json" -H "Content-Type:application/json" http://localhost:8083/connectors/ -d '{"name": "inventory-connector", "config": {"connector.class": "io.debezium.connector.mysql.MySqlConnector", "tasks.max": "1", "database.hostname": "mysql", "database.port": "3306", "database.user": "debezium", "database.password": "dbz", "database.server.id": "184054", "topic.prefix": "dbserver1", "table.include.list": "public.inventory", "schema.history.internal.kafka.bootstrap.servers": "kafka:9092", "schema.history.internal.kafka.topic": "dbhistory.inventory" } }' To register multiple connectors, submit a separate request for each one. Restart Kafka Connect to implement your changes. As Kafka Connect starts, it loads the configured Debezium connectors from the connector-plugins directory. After you complete the configuration, the deployed connector connects to the source database and produces events for each inserted, updated, or deleted row or document. Repeat Steps 5-10 for each Kafka Connect worker node. steps Verify the deployment . Additional resources Adding connector plugins 2.4. Verifying the deployment After the connector starts, it performs a snapshot of the configured database, and creates topics for each table that you specify. Prerequisites You deployed a connector on Red Hat Enterprise Linux, based on the instructions in Section 2.3, "Deploying Debezium with Streams for Apache Kafka on Red Hat Enterprise Linux" . Procedure From a terminal window on the host, enter the following command to request the list of connectors from the Kafka Connect API: USD curl -H "Accept:application/json" localhost:8083/connectors/ The query returns the name of the deployed connector, for example: From a terminal window on the host, enter the following command to view the tasks that the connector is running: USD curl -i -X GET -H "Accept:application/json" localhost:8083/connectors/inventory-connector The command returns output that is similar to the following example: HTTP/1.1 200 OK Date: Thu, 06 Feb 2020 22:12:03 GMT Content-Type: application/json Content-Length: 531 Server: Jetty(9.4.20.v20190813) { "name": "inventory-connector", ... "tasks": [ { "connector": "inventory-connector", "task": 0 } ] } Display a list of topics in the Kafka cluster. From a terminal window, navigate to /opt/kafka/bin/ and run the following shell script: ./kafka-topics.sh --bootstrap-server=localhost:9092 --list The Kafka broker returns a list of topics that the connector creates. The available topics depends on the settings of the connector's snapshot.mode , snapshot.include.collection.list , and table.include.list configuration properties. By default, the connector creates a topic for each non-system table in the database. View the contents of a topic. From a terminal window, navigate to /opt/kafka/bin/ , and run the kafka-console-consumer.sh shell script to display the contents of one of the topics returned by the preceding command: For example: ./kafka-console-consumer.sh \ > --bootstrap-server localhost:9092 \ > --from-beginning \ > --property print.key=true \ > --topic=dbserver1.inventory.products_on_hand For each event in the topic, the command returns information that is similar to the following output: Example 2.1. Content of a Debezium change event In the preceding example, the payload value shows that the connector snapshot generated a read ( "op" ="r" ) event from the table inventory.products_on_hand . The "before" state of the product_id record is null , indicating that no value exists for the record. The "after" state shows a quantity of 3 for the item with product_id 101 . Steps For information about the configuration settings that are available for each connector, and to learn how to configure source databases to enable change data capture, see the Debezium User Guide . 2.5. Updating Debezium connector plug-ins in the Kafka Connect cluster To replace the version of a Debezium connector that is deployed on Red Hat Enterprise Linux, you update the connector plug-in. Procedure Download a copy of the Debezium connector plug-in that you want to replace from the Software Downloads . Extract the contents of the Debezium connector archive to the /opt/kafka/connector-plugins directory. USD sudo unzip debezium-connector-mysql-2.7.3.Final.zip -d /opt/kafka/connector-plugins Restart Kafka Connect.

Commands:
{ "name": "inventory-connector", 1 "config": { "connector.class": "io.debezium.connector.mysql.MySqlConnector", 2 "tasks.max": "1", 3 "database.hostname": "mysql", 4 "database.port": "3306", 5 "database.user": "debezium", 6 "database.password": "dbz", 7 "database.server.id": "184054", 8 "topic.prefix": "dbserver1", 9 "table.include.list": "public.inventory", 10 "schema.history.internal.kafka.bootstrap.servers": "kafka:9092", 11 "schema.history.internal.kafka.topic": "dbhistory.inventory" 12 } }
sudo mkdir /opt/kafka/connector-plugins
sudo unzip debezium-connector-mysql-2.7.3.Final.zip -d /opt/kafka/connector-plugins
su - kafka Password:
jcmd | grep ConnectDistributed
18514 org.apache.kafka.connect.cli.ConnectDistributed /opt/kafka/config/connect-distributed.properties
kill 18514
plugin.path=/opt/kafka/connector-plugins
/opt/kafka/bin/connect-distributed.sh /opt/kafka/config/connect-distributed.properties
curl -i -X POST -H "Accept:application/json" -H "Content-Type:application/json" http://localhost:8083/connectors/ -d '{"name": "inventory-connector", "config": {"connector.class": "io.debezium.connector.mysql.MySqlConnector", "tasks.max": "1", "database.hostname": "mysql", "database.port": "3306", "database.user": "debezium", "database.password": "dbz", "database.server.id": "184054", "topic.prefix": "dbserver1", "table.include.list": "public.inventory", "schema.history.internal.kafka.bootstrap.servers": "kafka:9092", "schema.history.internal.kafka.topic": "dbhistory.inventory" } }'
curl -H "Accept:application/json" localhost:8083/connectors/
inventory-connector
curl -i -X GET -H "Accept:application/json" localhost:8083/connectors/inventory-connector
HTTP/1.1 200 OK Date: Thu, 06 Feb 2020 22:12:03 GMT Content-Type: application/json Content-Length: 531 Server: Jetty(9.4.20.v20190813) { "name": "inventory-connector", "tasks": [ { "connector": "inventory-connector", "task": 0 } ] }
./kafka-topics.sh --bootstrap-server=localhost:9092 --list
./kafka-console-consumer.sh > --bootstrap-server localhost:9092 > --from-beginning > --property print.key=true > --topic=dbserver1.inventory.products_on_hand
{"schema":{"type":"struct","fields":[{"type":"int32","optional":false,"field":"product_id"}],"optional":false,"name":"dbserver1.inventory.products_on_hand.Key"},"payload":{"product_id":101}} {"schema":{"type":"struct","fields":[{"type":"struct","fields":[{"type":"int32","optional":false,"field":"product_id"},{"type":"int32","optional":false,"field":"quantity"}],"optional":true,"name":"dbserver1.inventory.products_on_hand.Value","field":"before"},{"type":"struct","fields":[{"type":"int32","optional":false,"field":"product_id"},{"type":"int32","optional":false,"field":"quantity"}],"optional":true,"name":"dbserver1.inventory.products_on_hand.Value","field":"after"},{"type":"struct","fields":[{"type":"string","optional":false,"field":"version"},{"type":"string","optional":false,"field":"connector"},{"type":"string","optional":false,"field":"name"},{"type":"int64","optional":false,"field":"ts_ms"},{"type":"string","optional":true,"name":"io.debezium.data.Enum","version":1,"parameters":{"allowed":"true,last,false"},"default":"false","field":"snapshot"},{"type":"string","optional":false,"field":"db"},{"type":"string","optional":true,"field":"sequence"},{"type":"string","optional":true,"field":"table"},{"type":"int64","optional":false,"field":"server_id"},{"type":"string","optional":true,"field":"gtid"},{"type":"string","optional":false,"field":"file"},{"type":"int64","optional":false,"field":"pos"},{"type":"int32","optional":false,"field":"row"},{"type":"int64","optional":true,"field":"thread"},{"type":"string","optional":true,"field":"query"}],"optional":false,"name":"io.debezium.connector.mysql.Source","field":"source"},{"type":"string","optional":false,"field":"op"},{"type":"int64","optional":true,"field":"ts_ms"},{"type":"struct","fields":[{"type":"string","optional":false,"field":"id"},{"type":"int64","optional":false,"field":"total_order"},{"type":"int64","optional":false,"field":"data_collection_order"}],"optional":true,"field":"transaction"}],"optional":false,"name": "dbserver1.inventory.products_on_hand.Envelope" }, "payload" :{ "before" : null , "after" :{ "product_id":101,"quantity":3 },"source":{"version":"2.7.3.Final-redhat-00001","connector":"mysql","name":"inventory_connector_mysql","ts_ms":1638985247805,"snapshot":"true","db":"inventory","sequence":null,"table":"products_on_hand","server_id":0,"gtid":null,"file":"mysql-bin.000003","pos":156,"row":0,"thread":null,"query":null}, "op" : "r" ,"ts_ms":1638985247805,"transaction":null}}
sudo unzip debezium-connector-mysql-2.7.3.Final.zip -d /opt/kafka/connector-plugins