canal demo搭建全记录

一、环境介绍

canal是阿里开源的中间件,主要用于同步mysql数据库变更。具体参见:https://github.com/alibaba/canal/releases

搭建环境:

vmware centos7 部署mysql和canal

windows开发canal client,自动捕获mysql数据库变更

二、Centos安装Mysql

1、尝试用yum安装mysql

wget http://repo.mysql.com/mysql57-community-release-el7-10.noarch.rpm

返回:2018-07-13 16:04:42 (63.9 KB/s) - ‘mysql57-community-release-el7-10.noarch.rpm’ saved [25548/25548]

sudo rpm -Uvh mysql57-community-release-el7-10.noarch.rpm
sudo yum install -y mysql-community-server

如果执行顺利,安装mysql server 成功。
2.改用阿里源安装
可是官方的yum源在国内访问效果不佳,我下载mysql server的速度太慢了,决定改用阿里源

#下载wget
yum install wget -y

#备份当前的yum源
mv /etc/yum.repos.d /etc/yum.repos.d.backup4comex

#新建空的yum源设置目录
mkdir /etc/yum.repos.d

#下载阿里云的yum源配置
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo

#最后重建缓存
yum clean all
yum makecache

3.安装MariaDB
MariaDB数据库管理系统是MySQL的一个分支,主要由开源社区在维护,采用GPL授权许可。开发这个分支的原因之一是:甲骨文公司收购了MySQL后,有将MySQL闭源的潜在风险,因此社区采用分支的方式来避开这个风险。MariaDB的目的是完全兼容MySQL,包括API和命令行,使之能轻松成为MySQL的代替品。

安装mariadb,大小59 M。

[root@yl-web yl]# yum install mariadb-server mariadb

其它几条常用的mariadb命令:

systemctl start mariadb #启动MariaDB

systemctl stop mariadb #停止MariaDB

systemctl restart mariadb #重启MariaDB

systemctl enable mariadb #设置开机启动

运行systemctl start mariadb,然后就可以正常使用mysql了
4.设置数据库密码:

set password for 'root'@'localhost' =password('root');

5.遇到的几个问题
①从windows访问centos mysql失败

解决方案:设置mysql允许远程连接

mysql -u root;
//赋予任何主机访问数据的权限
mysql>GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' WITH GRANT OPTION;

//使修改生效
mysql>FLUSH PRIVILEGES;

②进行上述操作之后,发现仍然连接失败,返回错误

Can't connect to MySQL server on '10.168.12.43' (10060)

解决方案:从windows连接vmware里面的mysql失败,关闭windows防火墙后成功。

三、部署canal server

(参考:https://github.com/alibaba/canal/wiki/QuickStart
1.下载canal serverhttps://github.com/alibaba/canal/releases
Image

我下载的是canal.exaple-1.0.24.gar.gz,下载完成后解压缩:

mkdir /tmp/canal
tar zxvf canal.deployer-1.0.24.tar.gz  -C /tmp/canal

2.查看binlog相关数据库命令:

是否启用了日志
mysql>show variables like 'log_bin';

怎样知道当前的日志
mysql> show master status;

查看mysql binlog模式
show variables like 'binlog_format';

获取binlog文件列表
show binary logs;

查看当前正在写入的binlog文件
show master status\G

查看指定binlog文件的内容
show binlog events in 'mysql-bin.000002';

3.开启binlog
如果log_bin关闭,需要在etc下面找到my.cnf,开启binlog:

server-id=1
log-bin=/var/lib/mysql/mysql-bin

然后重启mysql服务。
4.添加canal mysql数据库账号

CREATE USER canal IDENTIFIED BY 'canal';
GRANT SELECT, REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'canal'@'%';

GRANT ALL PRIVILEGES ON *.* TO 'canal'@'%' ;

FLUSH PRIVILEGES;

5.配置canal实例,设置本地数据库信息
vi conf/example/instance.properties

## mysql serverId
canal.instance.mysql.slaveId = 1234
# position info
canal.instance.master.address = 10.168.12.43:3306
canal.instance.master.journal.name =mysql-bin.000003
canal.instance.master.position =
canal.instance.master.timestamp =

……

canal.instance.dbUsername = canal
canal.instance.dbPassword = canal
canal.instance.defaultDatabaseName =testcanal
canal.instance.connectionCharset = UTF-8

# table regex
canal.instance.filter.regex = .*\\..*

6.启动canal

sh bin/startup.sh

7.查看日志

vi logs/canal/canal.log
vi logs/example/example.log

四、canal lient demo

1.引入pom依赖

<dependency>
<groupId>com.alibaba.otter</groupId>
<artifactId>canal.client</artifactId>
<version>1.0.24</version>
</dependency>

2.客户端代码

public class ClientTest {
    public static void main(String args[]) {
        // 创建链接
        CanalConnector connector = CanalConnectors.newSingleConnector(new InetSocketAddress("10.168.12.43",
), "example", "", "");
        int batchSize = 1000;
        int emptyCount = 0;
        try {
            connector.connect();
            connector.subscribe(".*\\..*");
            connector.rollback();
            int totalEmptyCount = 120;
            while (emptyCount < totalEmptyCount) {
                Message message = connector.getWithoutAck(batchSize); // 获取指定数量的数据
                long batchId = message.getId();
                int size = message.getEntries().size();
                if (batchId == -1 || size == 0) {
                    emptyCount++;
                    System.out.println("empty count : " + emptyCount);
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                    }
                } else {
                    emptyCount = 0;
                    printEntry(message.getEntries());
                }

                connector.ack(batchId); // 提交确认
            }

            System.out.println("empty too many times, exit");
        } finally {
            connector.disconnect();
        }
    }

    private static void printEntry(List<Entry> entrys) {
        for (Entry entry : entrys) {
            if (entry.getEntryType() == EntryType.TRANSACTIONBEGIN || entry.getEntryType() == EntryType.TRANSACTIONEND) {
                continue;
            }

            RowChange rowChage = null;
            try {
                rowChage = RowChange.parseFrom(entry.getStoreValue());
            } catch (Exception e) {
                throw new RuntimeException("ERROR ## parser of eromanga-event has an error , data:" + entry.toString(),
                        e);
            }

            EventType eventType = rowChage.getEventType();
            System.out.println(String.format("================&amp;gt; binlog[%s:%s] , name[%s,%s] , eventType : %s",
                    entry.getHeader().getLogfileName(), entry.getHeader().getLogfileOffset(),
                    entry.getHeader().getSchemaName(), entry.getHeader().getTableName(),
                    eventType));

            for (RowData rowData : rowChage.getRowDatasList()) {
                if (eventType == EventType.DELETE) {
                    printColumn(rowData.getBeforeColumnsList());
                } else if (eventType == EventType.INSERT) {
                    printColumn(rowData.getAfterColumnsList());
                } else {
                    System.out.println("-------&amp;gt; before");
                    printColumn(rowData.getBeforeColumnsList());
                    System.out.println("-------&amp;gt; after");
                    printColumn(rowData.getAfterColumnsList());
                }
            }
        }
    }

    private static void printColumn(List<Column> columns) {
        for (Column column : columns) {
            System.out.println(column.getName() + " : " + column.getValue() + "    update=" + column.getUpdated());
        }
    }
}

3.建立数据库连接,进行insert,delete等数据库操作
Image(1)

Image(2)

五、遇到的问题

1.canal建立连接失败

解决方案:用telnet命令测试建立连接仍然失败,关闭linux防火墙。

systemctl stop firewalld.service

其他centos7防火墙相关命令:

firewall-cmd --list-ports#查看已经开放的端口:

firewall-cmd --reload #重启firewall

systemctl stop firewalld.service #停止firewall

systemctl disable firewalld.service #禁止firewall开机启动

firewall-cmd --state #查看默认防火墙状态(关闭后显示notrunning,开启后显示running)