io-cdc-canal.md

id	title	sidebar_label
io-cdc-canal	Canal source connector	Canal source connector

The Canal source connector pulls messages from MySQL to Pulsar topics.

This guide explains how to congifure and use Canal source connector.

Configuration

The configuration of Canal source connector has the following parameters.

Parameter

Name	Required	Default	Description
username	true	None	Canal server account (not MySQL).
password	true	None	Canal server password (not MySQL).
destination	true	None	Source destination that Canal source connector connects to.
singleHostname	false	None	Canal server address.
singlePort	false	None	Canal server port.
cluster	true	false	Whether to enable cluster mode based on Canal server configuration or not. true: cluster mode. If set to true, it talks to zkServers to figure out the actual database host. false: standalone mode. If set to false, it connects to the database specified by singleHostname and singlePort.
zkServers	true	None	Address and port of the Zookeeper that Canal source connector talks to figure out the actual database host.
batchSize	false	1000	Batch size to fetch from Canal.

Example

Before using the Canal connector, you can create a configuration file through one of the following methods.

• JSON

  {
      "zkServers": "127.0.0.1:2181",
      "batchSize": "5120",
      "destination": "example",
      "username": "",
      "password": "",
      "cluster": false,
      "singleHostname": "127.0.0.1",
      "singlePort": "11111",
  }

• YAML

  You can create a YAML file and copy the contents below to your YAML file.

  configs:
      zkServers: "127.0.0.1:2181"
      batchSize: "5120"
      destination: "example"
      username: ""
      password: ""
      cluster: false
      singleHostname: "127.0.0.1"
      singlePort: "11111"

Usage

Here is an example of storing MySQL data using the configuration file as above.

1. Start a MySQL server.

   $ docker pull mysql:5.7
   $ docker run -d -it --rm --name pulsar-mysql -p 3306:3306 -e MYSQL_ROOT_PASSWORD=canal -e MYSQL_USER=mysqluser -e MYSQL_PASSWORD=mysqlpw mysql:5.7

2. Create a configuration file mysqld.cnf.

   [mysqld]
   pid-file    = /var/run/mysqld/mysqld.pid
   socket      = /var/run/mysqld/mysqld.sock
   datadir     = /var/lib/mysql
   #log-error  = /var/log/mysql/error.log
   # By default we only accept connections from localhost
   #bind-address   = 127.0.0.1
   # Disabling symbolic-links is recommended to prevent assorted security risks
   symbolic-links=0
   log-bin=mysql-bin
   binlog-format=ROW
   server_id=1

3. Copy the configuration file mysqld.cnf to MySQL server.

   $ docker cp mysqld.cnf pulsar-mysql:/etc/mysql/mysql.conf.d/

4. Restart the MySQL server.

   $ docker restart pulsar-mysql

5. Create a test database in MySQL server.

   $ docker exec -it pulsar-mysql /bin/bash
   $ mysql -h 127.0.0.1 -uroot -pcanal -e 'create database test;'

6. Start a Canal server and connect to MySQL server.

   $ docker pull canal/canal-server:v1.1.2
   $ docker run -d -it --link pulsar-mysql -e canal.auto.scan=false -e canal.destinations=test -e canal.instance.master.address=pulsar-mysql:3306 -e canal.instance.dbUsername=root -e canal.instance.dbPassword=canal -e canal.instance.connectionCharset=UTF-8 -e canal.instance.tsdb.enable=true -e canal.instance.gtidon=false --name=pulsar-canal-server -p 8000:8000 -p 2222:2222 -p 11111:11111 -p 11112:11112 -m 4096m canal/canal-server:v1.1.2
   

7. Start Pulsar standalone.

   $ docker pull apachepulsar/pulsar:2.3.0
   $ docker run -d -it --link pulsar-canal-server -p 6650:6650 -p 8080:8080 -v $PWD/data:/pulsar/data --name pulsar-standalone apachepulsar/pulsar:2.3.0 bin/pulsar standalone

8. Modify the configuration file canal-mysql-source-config.yaml.

   configs:
       zkServers: ""
       batchSize: "5120"
       destination: "test"
       username: ""
       password: ""
       cluster: false
       singleHostname: "pulsar-canal-server"
       singlePort: "11111"

9. Create a consumer file pulsar-client.py.

   import pulsar
   
   client = pulsar.Client('pulsar://localhost:6650')
   consumer = client.subscribe('my-topic',
                               subscription_name='my-sub')
   
   while True:
       msg = consumer.receive()
       print("Received message: '%s'" % msg.data())
       consumer.acknowledge(msg)
   
   client.close()

10. Copy the configuration file canal-mysql-source-config.yaml and the consumer file pulsar-client.py to Pulsar server.

    $ docker cp canal-mysql-source-config.yaml pulsar-standalone:/pulsar/conf/
    $ docker cp pulsar-client.py pulsar-standalone:/pulsar/

11. Download a Canal connector and start it.

    $ docker exec -it pulsar-standalone /bin/bash
    $ wget https://archive.apache.org/dist/pulsar/pulsar-2.3.0/connectors/pulsar-io-canal-2.3.0.nar -P connectors
    $ ./bin/pulsar-admin source localrun \
    --archive ./connectors/pulsar-io-canal-2.3.0.nar \
    --classname org.apache.pulsar.io.canal.CanalStringSource \
    --tenant public \
    --namespace default \
    --name canal \
    --destination-topic-name my-topic \
    --source-config-file /pulsar/conf/canal-mysql-source-config.yaml \
    --parallelism 1

12. Consume data from MySQL.

    $ docker exec -it pulsar-standalone /bin/bash
    $ python pulsar-client.py

13. Open another window to log in MySQL server.

    $ docker exec -it pulsar-mysql /bin/bash
    $ mysql -h 127.0.0.1 -uroot -pcanal

14. Create a table, and insert, delete, and update data in MySQL server.

    mysql> use test;
    mysql> show tables;
    mysql> CREATE TABLE IF NOT EXISTS `test_table`(`test_id` INT UNSIGNED AUTO_INCREMENT,`test_title` VARCHAR(100) NOT NULL,
    `test_author` VARCHAR(40) NOT NULL,
    `test_date` DATE,PRIMARY KEY ( `test_id` ))ENGINE=InnoDB DEFAULT CHARSET=utf8;
    mysql> INSERT INTO test_table (test_title, test_author, test_date) VALUES("a", "b", NOW());
    mysql> UPDATE test_table SET test_title='c' WHERE test_title='a';
    mysql> DELETE FROM test_table WHERE test_title='c';