Mysql數據庫數據實時監控之canal

目前遇到一個需求，是基於mysql某表數據得變動，同步捕獲變動的數據，經分析，選擇阿里巴巴的canal作爲mysql實時監控的中間件。canal github地址

流程如下，抄襲的canal官網上的流程

canal我們可以選擇 server-client模式，這樣我們的client,就可以選擇自己喜歡的實現方式和業務邏輯去讀取server監聽到的mysql數據變化了。

首先，被監聽的mysql需要開啓binlog,也就是mysql數據的變化會寫道一個二進制的log文件中。

定位到mysql的my.cnf配置文件：

vim etc/my.cnf

添加開啓log_bin

server-id = 1
log_bin = /var/log/mysql-bin.log
binlog_format = ROW

server-id爲唯一即可；log_bin爲二進制log文件的保存地址；binlog_forrmat=ROW爲固定

重啓mysql，可以在
/var/log/下看到生成的日誌文件

其次，下載canal的server端，下載鏈接，下載canal.deployer-*.tar.gz，我選擇的是canal.deployer-1.1.2.tar.gz，下載並解壓到目錄下。

配置修改

vi conf/example/instance.properties

## mysql serverId
canal.instance.mysql.slaveId = 1234
#position info，需要改成自己的數據庫信息
canal.instance.master.address = 127.0.0.1:3306 
canal.instance.master.journal.name = 
canal.instance.master.position = 
canal.instance.master.timestamp = 
#canal.instance.standby.address = 
#canal.instance.standby.journal.name =
#canal.instance.standby.position = 
#canal.instance.standby.timestamp = 
#username/password，需要改成自己的數據庫信息
canal.instance.dbUsername = canal  
canal.instance.dbPassword = canal
canal.instance.defaultDatabaseName =
canal.instance.connectionCharset = UTF-8
#table regex
canal.instance.filter.regex = .\*\\\\..\*

這裏主要修改一下需要監聽的數據庫地址以及監聽數據庫中已創建的用戶名及密碼，這個用戶信息需要在被監聽數據庫中創建，如下，創建了一個canal用戶，並授權slave的權限

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

啓動 canal server

sh bin/startup.sh

如果在/canal/logs/example下看到有example.log,打開如下所示，即啓動成功

2020-05-12 14:21:46.488 [Thread-6] INFO  c.a.otter.canal.instance.core.AbstractCanalInstance - stop CannalInstance for null-example 
2020-05-12 14:21:47.038 [Thread-6] INFO  c.a.otter.canal.instance.core.AbstractCanalInstance - stop successful....
2020-05-12 14:21:54.472 [main] INFO  c.a.o.c.i.spring.support.PropertyPlaceholderConfigurer - Loading properties file from class path resource [canal.properties]
2020-05-12 14:21:54.478 [main] INFO  c.a.o.c.i.spring.support.PropertyPlaceholderConfigurer - Loading properties file from class path resource [example/instance.properties]
2020-05-12 14:21:54.763 [main] WARN  o.s.beans.GenericTypeAwarePropertyDescriptor - Invalid JavaBean property 'connectionCharset' being accessed! Ambiguous write methods found next to actually used [public void com.alibaba.otter.canal.parse.inbound.mysql.AbstractMysqlEventParser.setConnectionCharset(java.lang.String)]: [public void com.alibaba.otter.canal.parse.inbound.mysql.AbstractMysqlEventParser.setConnectionCharset(java.nio.charset.Charset)]
2020-05-12 14:21:54.814 [main] INFO  c.a.o.c.i.spring.support.PropertyPlaceholderConfigurer - Loading properties file from class path resource [canal.properties]
2020-05-12 14:21:54.815 [main] INFO  c.a.o.c.i.spring.support.PropertyPlaceholderConfigurer - Loading properties file from class path resource [example/instance.properties]
2020-05-12 14:21:55.068 [main] ERROR com.alibaba.druid.pool.DruidDataSource - testWhileIdle is true, validationQuery not set
2020-05-12 14:21:55.475 [main] INFO  c.a.otter.canal.instance.spring.CanalInstanceWithSpring - start CannalInstance for 1-example 
2020-05-12 14:21:55.516 [main] INFO  c.a.otter.canal.instance.core.AbstractCanalInstance - start successful....
2020-05-12 14:21:55.646 [destination = example , address = /127.0.0.1:3306 , EventParser] WARN  c.a.o.c.p.inbound.mysql.rds.RdsBinlogEventParserProxy - ---> begin to find start position, it will be long time for reset or first position
2020-05-12 14:21:55.647 [destination = example , address = /127.0.0.1:3306 , EventParser] WARN  c.a.o.c.p.inbound.mysql.rds.RdsBinlogEventParserProxy - prepare to find start position just show master status
2020-05-12 14:21:56.453 [destination = example , address = /127.0.0.1:3306 , EventParser] WARN  c.a.o.c.p.inbound.mysql.rds.RdsBinlogEventParserProxy - ---> find start position successfully, EntryPosition[included=false,journalName=mysql-bin.000001,position=62749,serverId=1,gtid=<null>,timestamp=1589262896000] cost : 793ms , the next step is binlog dump
2020-05-12 14:22:30.986 [New I/O server worker #1-1] INFO  c.a.otter.canal.instance.core.AbstractCanalInstance - subscribe filter change to .*\..*
2020-05-12 14:29:06.059 [New I/O server worker #1-2] INFO  c.a.otter.canal.instance.core.AbstractCanalInstance - subscribe filter change to .*\..*

注意該server啓動後默認端口爲11111

然後，配置client端來讀取server監聽到的數據變化。我這裏是創建了一個springboot

pom.xml中依賴：

<dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba.otter</groupId>
            <artifactId>canal.client</artifactId>
            <version>1.1.0</version>
        </dependency>
    </dependencies>

寫一個java類，main函數裏寫讀取變化數據的邏輯

package com.hjsc.canalclient.client;

import java.net.InetSocketAddress;
import java.util.List;


import com.alibaba.otter.canal.client.CanalConnectors;
import com.alibaba.otter.canal.client.CanalConnector;
import com.alibaba.otter.canal.common.utils.AddressUtils;
import com.alibaba.otter.canal.protocol.Message;
import com.alibaba.otter.canal.protocol.CanalEntry.Column;
import com.alibaba.otter.canal.protocol.CanalEntry.Entry;
import com.alibaba.otter.canal.protocol.CanalEntry.EntryType;
import com.alibaba.otter.canal.protocol.CanalEntry.EventType;
import com.alibaba.otter.canal.protocol.CanalEntry.RowChange;
import com.alibaba.otter.canal.protocol.CanalEntry.RowData;

public class CanalClientExample {

    public static void main(String args[]) {
        // 創建鏈接
        CanalConnector connector = CanalConnectors.newSingleConnector(new InetSocketAddress(AddressUtils.getHostIp(),
                11111), "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); // 獲取指定數量的數據
                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;
                    // System.out.printf("message[batchId=%s,size=%s] \n", batchId, size);
                    printEntry(message.getEntries());
                }

                connector.ack(batchId); // 提交確認
                // connector.rollback(batchId); // 處理失敗, 回滾數據
            }

            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("================&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("-------&gt; before");
                    printColumn(rowData.getBeforeColumnsList());
                    System.out.println("-------&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());
        }
    }


}

springboot 項目打成jar包後，我需要執行入口是這個類的main函數，所以在pom.xml中要添加main-class入口，如下：

 <properties>
        <start-class>com.hjsc.canalclient.client.CanalClientExample</start-class>
        <java.version>1.8</java.version>
    </properties>

最後，數據庫端的變化，就會在client端讀取到了，實時監聽搭建完畢。