mysql router是mysql官方提供的一个轻量级中间件，是innodb cluster的一部分，可在应用程序和后端mysql服务器之间提供透明路由；它主要用以解决mysql主从库集群的高可用、负载均衡、易扩展等问题。mysql router为数据库集群提供一个虚拟ip作为应用程序单一连接点，通过这个单一的连接点实现负载均衡，读写分离，故障转移等数据库高可用方案。
本教程操作环境：windows7系统、mysql8版本、dell g3电脑。
一、介绍1.1mysql router简介mysql router是mysql官方提供的一个轻量级中间件，是innodb cluster的一部分，可在应用程序和后端mysql服务器之间提供透明路由。主要用以解决mysql主从库集群的高可用、负载均衡、易扩展等问题。router作为一个流量转发层，位于应用与mysql服务器之间，其功能类似于lvs。
1.2为什么要用mysql router？基于组复制(mgr)的机制，当主节点宕机离开集群，剩余的其他节点会基于paxos协议选举一个新的主节点。这里有一个问题，应用程序端如果连接到了主节点，这时主节点宕机离开集群，可用的数据库ip地址发生变化，客户端应用程序这个时候还是会向失败的节点尝试连接，虽然可以修改客户端应用程序的连接配置，但是这种情况基本是不现实的。
1.3mysql router关系图
结合mysql group replication和mysql shel如下：
上图充分说明了mysql router在innodb集群里面的角色，主要作用是为数据库集群提供一个虚拟ip作为应用程序单一连接点，通过这个单一的连接点实现负载均衡，读写分离，故障转移等数据库高可用方案。
mysql router推荐安装在应用程序所在的机器上，原因包括：
通过本地unix套接字连接，而不是tcp/ip，提升性能降低网络延迟mysql实例不需要额外的账号，只需要一个router@198.51.100.45, 而不是myapp@%提升应用程序服务器的可扩展性1.4mysql cluster简介cluster是这个高可用方案中的一个虚拟节点，它会在mgr的所有成员上创建一个名为mysql_innodb_cluster_metadata的数据库，存储集群的元数据信息，包括集群信息、集群成员、组复制信息、连接的mysql router等信息，以提供mysql router查询。它相当于对组复制上的成员做了一层逻辑上的封装，以一个集群的模式展现出来，各节点的状态与对应实例在组复制中成员的状态实时同步，但是集群的节点与组复制的成员只在创建集群时同步，后期组复制的成员变更并不自动同步到集群中，可以在集群中做手动的节点增减，这样使得面向应用端的具体实例实现了更可控更灵活的高可用。
二、环境准备主机名ip地址角色
oratest51 172.16.9.51 primary
oratest52 172.16.9.52 seconde
test61 172.16.9.61 seconde
node4 172.16.8.68 mysql router
操作系统：centos linux release 7.2.1511
mysql版本：mysql-5.7.26-linux-glibc2.12-x86_64
mysql router版本：mysql-router-8.0.17-linux-glibc2.12-x86_64
mysql shell版本：mysql-shell-8.0.17-linux-glibc2.12-x86-64bit
三、安装和配置mysql routermysql router有两种部署模式：
bootstrap模式：支持failover，必须结合innodb cluster使用，在--directory指定的路径下自动生成安装目录，配置文件里的端口为6446和6447。简单模式：不支持failover，无需结合innodb cluster使用，一般在主从复制或者主主复制等模式下使用，使用/usr/local/mysqlrouter/share/doc/mysqlrouter/sample_mysqlrouter.conf这个配置文件部署。3.1bootstrap模式安装mysql router注意： 使用bootstrap的方式安装mysql router的前提条件是mgr已装好，mysql shell已装好，innodb cluster已经配置好
3.1.1使用yum源的方式安装mysql router# wget -p /software/ https://repo.mysql.com//mysql80-community-release-el7-3.noarch.rpm# rpm -uvh /software/mysql80-community-release-el7-3.noarch.rpm# yum -y install mysql-router
3.1.2查看mysql router的默认配置[root@node4 yum.repos.d]# mysqlrouter --helpmysql router ver 8.0.16 for linux on x86_64 (mysql community - gpl)copyright (c) 2015, 2019, oracle and/or its affiliates. all rights reserved.oracle is a registered trademark of oracle corporation and/or itsaffiliates. other names may be trademarks of their respectiveowners.configuration read from the following files in the given order (enclosedin parentheses means not available for reading): /etc/mysqlrouter/mysqlrouter.conf (/root/.mysqlrouter.conf)plugins path: /usr/lib64/mysqlrouterdefault log directory: /var/log/mysqlrouterdefault persistent data directory: /var/lib/mysqlrouterdefault runtime state directory: /run/mysqlrouter
通过mysqlrouter --help可以看到默认的一些路径：
- 配置文件：/etc/mysqlrouter/mysqlrouter.conf
- 插件路径：/usr/lib64/mysqlrouter
- 日志路径：/var/log/mysqlrouter
- 持久化数据路径：/var/lib/mysqlrouter
- 运行时状态路径：/run/mysqlrouter
如果在mysqlrouter命令行使用--config或-c选项传入用户定义的配置文件，则不会加载默认配置文件。
3.1.3初始化mysql router，地址填primary的地址[root@node4 tmp]# mysqlrouter --bootstrap root@172.16.9.51:3306 --directory /data/mysqlrouter --conf-use-sockets --user=rootplease enter mysql password for root: warning: the mysql server does not have ssl configured and metadata used by the router may be transmitted unencrypted.# bootstrapping mysql router instance at '/data/mysqlrouter'...- checking for old router accounts - no prior router accounts found- creating mysql account mysql_router1_zhi3m2uhudci@'%' for cluster management- storing account in keyring- adjusting permissions of generated files- creating configuration /data/mysqlrouter/mysqlrouter.conf# mysql router configured for the innodb cluster 'st' #innodb集群名after this mysql router has been started with the generated configuration $ mysqlrouter -c /data/mysqlrouter/mysqlrouter.confthe cluster 'st' can be reached by connecting to:## mysql classic protocol- read/write connections: localhost:6446, /data/mysqlrouter/mysql.sock- read/only connections: localhost:6447, /data/mysqlrouter/mysqlro.sock## mysql x protocol- read/write connections: localhost:64460, /data/mysqlrouter/mysqlx.sock- read/only connections: localhost:64470, /data/mysqlrouter/mysqlxro.sock
--bootstrap：引导并配置router以便与mysql innodb集群一起运行。
3.1.4编辑配置文件，一般只需要配置bootstrap_server_addresses这一行即可# file automatically generated during mysql router bootstrap[default]user=rootlogging_folder=/data/mysqlrouter/logruntime_folder=/data/mysqlrouter/rundata_folder=/data/mysqlrouter/datakeyring_path=/data/mysqlrouter/data/keyringmaster_key_path=/data/mysqlrouter/mysqlrouter.keyconnect_timeout=15read_timeout=30#dynamic_state=/data/mysqlrouter/data/state.json[logger]level = info[metadata_cache:st]router_id=14bootstrap_server_addresses=mysql://oratest51:3306,mysql://oratest52:3306,mysql://test61:3306user=mysql_router14_ebhje7bsnckcmetadata_cluster=stttl=300use_gr_notifications=0[routing:st_default_rw]bind_address=0.0.0.0bind_port=6446socket=/data/mysqlrouter/mysql.sockdestinations=metadata-cache://st/default?role=primaryrouting_strategy=first-availableprotocol=classic[routing:st_default_ro]bind_address=0.0.0.0bind_port=6447socket=/data/mysqlrouter/mysqlro.sockdestinations=metadata-cache://st/default?role=secondaryrouting_strategy=round-robin-with-fallbackprotocol=classic[routing:st_default_x_rw]bind_address=0.0.0.0bind_port=64460socket=/data/mysqlrouter/mysqlx.sockdestinations=metadata-cache://st/default?role=primaryrouting_strategy=first-availableprotocol=x[routing:st_default_x_ro]bind_address=0.0.0.0bind_port=64470socket=/data/mysqlrouter/mysqlxro.sockdestinations=metadata-cache://st/default?role=secondaryrouting_strategy=round-robin-with-fallbackprotocol=x
3.1.5启动mysql router[root@node2 mysqlrouter]# cd /data/mysqlrouter/[root@node2 mysqlrouter]# sh start.sh
启动过程较慢，日志里可以看到启动信息
3.1.6测试连接mysql router默认情况下，使用6446作为rw端口，使用6447作为ro端口
# mysql -uroot -p123456 -h172.16.8.68 -p6446# mysql -uroot -p123456 -h172.16.8.68 -p6447# netstat -ntlp |grep mysqlrouter
3.2简单模式安装mysql router3.2.1下载软件包并上传到服务器[root@node4 etc]# mkdir /software;cd /software[root@node4 etc]# wget https://cdn.mysql.com//downloads/mysql-router/mysql-router-8.0.17-linux-glibc2.12-x86_64.tar.xz
3.2.2解压到指定目录[root@node4 etc]# tar -jxvf /software/mysql-router-8.0.17-linux-glibc2.12-x86_64.tar.xz -c /usr/local/[root@node4 etc]# cd /usr/local[root@node4 etc]# mv mysql-router-8.0.17-linux-glibc2.12-x86_64/ mysqlrouter
3.2.3设置环境变量[root@node4 etc]# echo 'export path=/usr/local/mysqlrouter/bin/:$path' >> /etc/profile[root@node4 etc]# source /etc/profile
3.2.4编辑配置文件# mkdir -p /usr/local/mysqlrouter/etc# cp /usr/local/mysqlrouter/share/doc/mysqlrouter/sample_mysqlrouter.conf /usr/local/mysqlrouter/etc# mv /usr/local/mysqlrouter/etc/sample_mysqlrouter.conf /usr/local/mysqlrouter/etc/mysqlrouter.conf# vim /usr/local/mysqlrouter/etc/mysqlrouter.conf##部分省略[default]logging_folder =/usr/local/mysqlrouter/log/plugin_folder = /usr/local/mysqlrouter/lib/mysqlrouter/config_folder = /usr/local/mysqlrouter/etc/runtime_folder = /usr/local/mysqlrouter/run/data_folder = /usr/local/mysqlrouter/data/keyring_path = /var/lib/keyring-datamaster_key_path = /var/lib/keyring-key[logger]level = info[routing:masters]bind_address = 172.16.8.68:7002destinations = 172.16.9.61:3306mode = read-writeconnect_timeout = 2[routing:slaves]bind_address = 172.16.8.68:7001destinations = 172.16.9.51:3306,172.16.9.52:3306mode = read-onlyconnect_timeout = 1##部分省略
/usr/local/mysqlrouter/share/doc/mysqlrouter/sample_mysqlrouter.conf这个是mysql router的参照配置文件，所以这里先把模板复制出来。
mysql router默认会寻找安装目录下的mysqlrouter.conf和家目录下的.mysqlrouter.conf。也可以在二进制程序mysqlrouter命令下使用-c或者--config手动指定配置文件。
mysql router的配置文件是片段式的，常用的就3个片段：[default]、[logger]、[routing:name]，片段名称区分大小写，且只支持单行#或;注释。
bind_address：添加mysql router所在机器的ipdestinations：后端的mysql服务器ip+端口mode：提供两种mode，read-only和read-write，read-write的调度方式为first-available，read-only的调度方式为round-robinconnect_timeout：连接超时时间routing_strategy：路由策略，有round-robin和first-available策略如果是多主模式，配置文件如下
[routing:mutili_rw]bind_address=172.16.8.68bind_port=7003destinations=172.16.9.51:3306,172.16.9.52:3306,172.16.9.61:3306mode=read-writeconnect_timeout=2protocol=classic
3.2.5创建上一步中配置文件里指定的目录[root@node4 etc]# mkdir -p /usr/local/mysqlrouter/run/[root@node4 etc]# mkdir -p /usr/local/lib/mysqlrouter[root@node4 etc]# mkdir -p /usr/local/mysqlrouter/etc/[root@node4 etc]# mkdir -p /usr/local/mysqlrouter/run/[root@node4 etc]# mkdir -p /usr/local/mysqlrouter/data/[root@node4 etc]# mkdir -p /usr/local/mysqlrouter/log/
3.2.6启动mysql router[root@node4 etc]# mysqlrouter --config /usr/local/mysqlrouter/etc/mysqlrouter.conf &
3.2.7查看mysql router的端口监听是否已开启[root@node4 etc]# netstat -ntlp |grep mysqlroutertcp 0 0 172.16.8.68:7001 0.0.0.0:* listen 9221/mysqlrouter tcp 0 0 172.16.8.68:7002 0.0.0.0:* listen 9221/mysqlrouter
mysql router的停止暂时没有停止脚本，如果要停止需要用kill -9的方式杀掉进程
四、功能测试以下测试都是在innodb cluster下，mysql router的安装模式是bootstrap
4.1路由验证4.1.1测试通过mysql router连接6446 rw端口，查看连接的是否为primary[root@node4 mysqlrouter]# for ((i=0;i<=5;i++));do mysql -h172.16.8.101 -uroot -p123456 -p6446 -e"select @@hostname;";done;mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| oratest51 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| oratest51 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| oratest51 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| oratest51 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| oratest51 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| oratest51 |+------------+
测试结果： 使用6446 rw端口会访问到后端innodb cluster的primary
4.1.2测试通过mysql router连接6447 ro端口，查看连接的是否为seconde节点，rr算法是否生效[root@node4 mysqlrouter]# for ((i=0;i<=5;i++));do mysql -h172.16.8.101 -uroot -p123456 -p6447 -e"select @@hostname;";done;mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| oratest52 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| test61 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| oratest52 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| test61 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| oratest52 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| test61 |+------------+
测试结果： 使用6447 ro端口会连接到后端innodb cluster集群中所有的seconde节点，并且以rr(round-robin)的策略调度
4.2高可用测试4.2.1模拟其中一台seconde节点宕机，查看mysql router是否会自动取消该节点的路由(1) 停掉一台seconde节点
[root@oratest52 ~]# systemctl status mysql[root@oratest52 ~]# systemctl stop mysql[root@oratest52 ~]# systemctl status mysql
(2) 在innodb cluster中查看集群状态，可以看到oratest52已经处于missing状态
mysql 172.16.9.51:3306 js > cluster.status(){ clustername: st, defaultreplicaset: { name: default, primary: oratest51:3306, ssl: disabled, status: ok_no_tolerance, statustext: cluster is not tolerant to any failures. 1 member is not active, topology: { oratest51:3306: { address: oratest61:3306, mode: r/o, readreplicas: {}, role: ha, status: online }, oratest52:3306: { address: oratest52:3306, mode: n/a, readreplicas: {}, role: ha, shellconnecterror: mysql error 2003 (hy000): can't connect to mysql server on 'oratest52' (111), status: (missing) }, test61:3306: { address: test51:3306, mode: r/w, readreplicas: {}, role: ha, status: online } }, topologymode: single-primary }, groupinformationsourcemember: test61:3306}
(3) 在mgr中查看gr状态，可以看到已经没有oratest52这台机器
mysql> select * from performance_schema.replication_group_members;+---------------------------+--------------------------------------+-------------+-------------+--------------+| channel_name | member_id | member_host | member_port | member_state |+---------------------------+--------------------------------------+-------------+-------------+--------------+| group_replication_applier | 48cdca42-a386-11e9-95f1-0050569d2587 | test61 | 3306 | online || group_replication_applier | e9ee5267-a386-11e9-ac35-0050569d9ef5 | oratest51 | 3306 | online |+---------------------------+--------------------------------------+-------------+-------------+--------------+
(4) 测试通过6447 ro端口连接，查看是否会自动剔除宕机的oratest52节点
[root@node4 ~]# for ((i=0;i<=5;i++));do mysql -h172.16.8.101 -uroot -p123456 -p6447 -e"select @@hostname;";done;mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| test61 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| test61 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| test61 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| test61 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| test61 |+------------+
测试结果： mysql router会自动剔除宕机的oratest52节点，read请求只会转发到后端正常的mysql实例，过程无需人工干预。
4.2.2启动上一步中停止的mysql实例，确认mgr和innodb cluster一切正常后，查看mysql router是否会自动加入这台已恢复的实例进行转发(1) 启动oratest52的mysql服务
[root@oratest52 ~]# systemctl start mysql
(2)启动mgr，并确认mgr状态正常
mysql> start group_replication;query ok, 0 rows affected (2.92 sec)mysql> select * from performance_schema.replication_group_members;+---------------------------+--------------------------------------+-------------+-------------+--------------+| channel_name | member_id | member_host | member_port | member_state |+---------------------------+--------------------------------------+-------------+-------------+--------------+| group_replication_applier | 48cdca42-a386-11e9-95f1-0050569d2587 | test61 | 3306 | online || group_replication_applier | 50bc1160-a386-11e9-92c9-0050569dc0da | oratest52 | 3306 | online || group_replication_applier | e9ee5267-a386-11e9-ac35-0050569d9ef5 | oratest51 | 3306 | online |+---------------------------+--------------------------------------+-------------+-------------+--------------+
(3) 检查innodb cluster是否正常
mysql 172.16.9.51:3306 js > cluster.status(){ clustername: st, defaultreplicaset: { name: default, primary: oratest51:3306, ssl: disabled, status: ok, statustext: cluster is online and can tolerate up to one failure., topology: { oratest51:3306: { address: oratest61:3306, mode: r/o, readreplicas: {}, role: ha, status: online }, oratest52:3306: { address: oratest52:3306, mode: r/o, readreplicas: {}, role: ha, status: online }, test61:3306: { address: test51:3306, mode: r/w, readreplicas: {}, role: ha, status: online } }, topologymode: single-primary }, groupinformationsourcemember: test61:3306}
(4) 查看恢复正常的实例，能不能自动加入mysql router进行转发，可以看到oratest52可以被正常调度
[root@node4 mysqlrouter]# for ((i=0;i<=5;i++));do mysql -h172.16.8.101 -uroot -p123456 -p6447 -e"select @@hostname;";done;mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| oratest52 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| test61 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| oratest52 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| test61 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| oratest52 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| test61 |+------------+
测试结果： 恢复正常的mysql实例可以自动加入mysql router并进行转发，无需人工干预。
4.2.3模拟停掉primary节点，测试mysql router如何处理发送rw端口的请求，mysql router怎样获取新的primary节点(1) 当前primary节点是oratest51，在primary节点上停止mysql，确认停止成功
[root@oratest51 data]# systemctl status mysql[root@oratest51 data]# systemctl stop mysql[root@oratest51 data]# systemctl status mysql[root@oratest51 data]# ps -ef |grep mysql
(2) 查看innodb cluster状态，可以看到oratest51已经处于missing状态，primary节点已经切换到了test61
mysql 172.16.9.61:3306 js > cluster.status();{ clustername: st, defaultreplicaset: { name: default, primary: test61:3306, ssl: disabled, status: ok_no_tolerance, statustext: cluster is not tolerant to any failures. 1 member is not active, topology: { oratest51:3306: { address: oratest51:3306, mode: n/a, readreplicas: {}, role: ha, shellconnecterror: mysql error 2003 (hy000): can't connect to mysql server on 'oratest51' (111), status: (missing) }, oratest52:3306: { address: oratest52:3306, mode: r/o, readreplicas: {}, role: ha, status: online }, test61:3306: { address: test61:3306, mode: r/w, readreplicas: {}, role: ha, status: online } }, topologymode: single-primary }, groupinformationsourcemember: test61:3306}
(3) 测试连接到rw 6446端口，查看是否可以正常连接到新的primary节点test61，并且写入数据否正常
[root@node2 mysqlrouter]# for ((i=0;i<=5;i++));do mysql -h172.16.8.101 -uroot -p123456 -p6446 -e"select @@hostname;";done;mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| test61 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| test61 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| test61 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| test61 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| test61 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| test61 |+------------+
测试结果： 当primary节点挂掉之后，mysql router会自动去连接新的primary节点
4.2.4启动上一步中停掉的oratest51，将状态恢复正常，测试mysql router能不能自动加入这台已恢复的节点并调度(1) 启动oratest51，将状态恢复正常
[root@oratest51 ~]# systemctl start mysql[root@oratest51 ~]# systemctl status mysql[root@oratest51 ~]# mysql -uroot -p123456mysql> start group_replication;mysql> select * from performance_schema.replication_group_members;+---------------------------+--------------------------------------+------------+-------------+--------------+| channel_name | member_id |member_host | member_port | member_state |+---------------------------+--------------------------------------+------------+-------------+--------------+| group_replication_applier | 48cdca42-a386-11e9-95f1-0050569d2587 |test61 | 3306 | online || group_replication_applier | 50bc1160-a386-11e9-92c9-0050569dc0da |oratest52 | 3306 | online || group_replication_applier | e9ee5267-a386-11e9-ac35-0050569d9ef5 |oratest51 | 3306 | online |+---------------------------+--------------------------------------+------------+-------------+--------------+3 rows in set (0.00 sec)mysql> quit[root@oratest51 local]# mysqlsh mysql js > shell.connect('root@172.16.9.51:3306') mysql 172.16.9.51:3306 js > var cluster = dba.getcluster() mysql 172.16.9.51:3306 js > cluster.status();{ clustername: st, defaultreplicaset: { name: default, primary: test61:3306, ssl: disabled, status: ok, statustext: cluster is online and can tolerate up to one failure., topology: { oratest51:3306: { address: oratest51:3306, mode: r/o, readreplicas: {}, role: ha, status: online }, oratest52:3306: { address: oratest52:3306, mode: r/o, readreplicas: {}, role: ha, status: online }, test61:3306: { address: test61:3306, mode: r/w, readreplicas: {}, role: ha, status: online } }, topologymode: single-primary }, groupinformationsourcemember: test61:3306}
(2) 测试ro端口的router调度
[root@node4 mysqlrouter]# for ((i=0;i<=5;i++));do mysql -h172.16.8.101 -uroot -p123456 -p6447 -e"select @@hostname;";done;mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| oratest52 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| oratest51 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| oratest52 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| oratest51 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| oratest52 |+------------+mysql: [warning] using a password on the command line interface can be insecure.+------------+| @@hostname |+------------+| test61 |+------------+
测试结果： 恢复正常的实例加入集群后，会自动加入到mysql router并进行调度
五、运维相关5.1数据库节点变更mysql router在初始化配置的时候是连接到集群节点读取集群的元数据的。如果在集群中新增或减少节点，需要同步更新mysql router的配置，否则无法生效
# mysqlrouter --bootstrap 172.16.9.51:3306 --directory /data/mysqlrouter --user=root --conf-use-sockets --force
更新了mysql router的配置的配置，需要重启mysql router：
#systemctl restart mysqlrouter#systemctl status mysqlrouter
六、问题汇总6.1初始化mysql router前，需要停止group_replication6.2使用--bootstrap初始化mysql router报错unable to connect to the metadata server报错如下
[root@oratest51 data]# mysqlrouter --bootstrap root@172.16.9.51:3310 --directory /data/mysqlrouter --conf-use-sockets --user=rootplease enter mysql password for root: error: unable to connect to the metadata server: error connecting to mysql server at 172.16.9.51:3310: can't connect to mysql server on '172.16.9.51' (111) (2003)
原因： 需要配置连接用户的权限
解决办法： 给连接用户配置所有权限，如下：
mysql> grant all privileges on *.* to root@'%' identified by 123456;mysql> flush privileges;
6.3使用--bootstrap初始化mysql router报错缺少mysql_innodb_cluster_metadata.schema_version表[root@oratest51 data]# mysqlrouter --bootstrap root@172.16.9.51:3306 --directory /data/mysqlrouter --conf-use-sockets --user=rootplease enter mysql password for root: error: expected mysql server '172.16.9.51:3306' to contain the metadata of mysql innodb cluster, but the schema does not exist.checking version of the metadata schema failed with: error executing mysql query: table 'mysql_innodb_cluster_metadata.schema_version' doesn't exist (1146)see https://dev.mysql.com/doc/refman/en/mysql-innodb-cluster-creating.html for instructions on setting up a mysql server to act as an innodb cluster metadata server
原因： 没有创建innodb cluster集群，创建innodb cluster集群后会自动生成这张表。mysql_innodb_cluster_metadata.schema_version表的用途是mysql router在进行调度分配的时候，需要读取这张表的内容来做调度策略。
解决办法： 创建innodb cluster集群
6.4启动mysql router hang住不动，查看日志报错error: bootstrap_server_addresses is not allowed when dynamic state file is used具体如下：
[root@node2 log]# tailf /root/mysqlrouter/log/mysqlrouter.log 2019-08-02 15:37:52 routing info [7f9721e2d700] [routing:st_default_ro] started: listening using /root/mysqlrouter/mysqlro.sock2019-08-02 15:37:52 routing info [7f972162c700] [routing:st_default_rw] started: listening using /root/mysqlrouter/mysql.sock2019-08-02 15:37:52 routing info [7f9720e2b700] [routing:st_default_x_ro] started: listening using /root/mysqlrouter/mysqlxro.sock2019-08-02 15:37:52 routing info [7f9713fff700] [routing:st_default_x_rw] started: listening on 0.0.0.0:64460, routing strategy = first-available2019-08-02 15:37:52 routing info [7f9713fff700] [routing:st_default_x_rw] started: listening using /root/mysqlrouter/mysqlx.sock2019-08-02 15:37:52 routing info [7f9713fff700] [routing:st_default_x_rw] stopped2019-08-02 15:37:52 routing info [7f9721e2d700] [routing:st_default_ro] stopped2019-08-02 15:37:52 routing info [7f972162c700] [routing:st_default_rw] stopped2019-08-02 15:37:52 routing info [7f9720e2b700] [routing:st_default_x_ro] stopped2019-08-02 15:37:52 main error [7f9726f1b880] error: bootstrap_server_addresses is not allowed when dynamic state file is used
原因： 开启了dynamic_state
解决办法： 在配置文件中注释掉dynamic_state所在行，例如下列第11行
1 # file automatically generated during mysql router bootstrap 2 [default] 3 user=root 4 logging_folder=/root/mysqlrouter/log 5 runtime_folder=/root/mysqlrouter/run 6 data_folder=/root/mysqlrouter/data 7 keyring_path=/root/mysqlrouter/data/keyring 8 master_key_path=/root/mysqlrouter/mysqlrouter.key 9 connect_timeout=1510 read_timeout=3011 #dynamic_state=/root/mysqlrouter/data/state.json
6.5启动mysql router hang住不动，查看日志报错unable to fetch live group_replication member data from any server in replicaset 'default'具体如下：
[root@node2 log]# tailf /root/mysqlrouter/log/mysqlrouter.log 2019-08-02 15:46:41 metadata_cache warning [7f3030405700] while updating metadata, could not establish a connection to replicaset 'default' through test61:33062019-08-02 15:46:51 metadata_cache warning [7f3030405700] while updating metadata, could not establish a connection to replicaset 'default' through oratest52:33062019-08-02 15:47:01 metadata_cache warning [7f3030405700] while updating metadata, could not establish a connection to replicaset 'default' through oratest51:33062019-08-02 15:47:01 metadata_cache error [7f3030405700] unable to fetch live group_replication member data from any server in replicaset 'default'
原因： mysql router所在节点没有配置本机dns解析
解决办法： 在/etc/hosts中添加mgr实例的解析
七、个人总结mysql router有两种部署模式：bootstrap模式：支持failover，必须结合innodb cluster使用，在--directory指定的路径下自动生成安装目录，配置文件里的端口为6446和6447。简单模式：不支持failover，无需结合innodb cluster使用，一般在主从复制或者主主复制等模式下使用，使用/usr/local/mysqlrouter/share/doc/mysqlrouter/sample_mysqlrouter.conf这个配置文件部署。mysql router使用的是一个ip地址(可以理解为vip)加一个rw端口和一个ro端口实现读写分离，router自身不能判断应用程序的请求是读还是写，因此做读写分离时，必须指定两个端口，如果应用程序不便指定两个端口，也可以全部指定rw端口，这样的话从节点就只作高可用，不做读写分离。mysql router自身存在单点故障隐患，官方推荐在每个应用程序所在机器上部署router，本机器连接本机器的router。也可以在router的上层在搭建一个高可用服务，如果是自建机房可以选择keepalived、pacemaker等方案；通过bootstrap生成的配置文件，只需要在bootstrap_server_addresses这一栏里配置就可以了，格式如下：bootstrap_server_addresses=mysql://oratest51:3306,mysql://oratest52:3306,mysql://test61:3306
mysql router的后端mysql实例挂掉之后，无需人工干预，mysql router会自动剔除挂了的mysql实例，当挂了的mysql实例恢复后会自动加入mysql router的后端服务器，也无需人工干预。mgr架构可以实现高可用，但是要实现failover，则需要安装innodb cluster了。mysql shell和mysql router是innodb cluster集群的一部分mysql router非常轻量级，性能损耗小于1%，官方建议每台应用上部署一个mysqlrouter节点，优点是节省网络带宽。缺点是mysqlrouter太轻量级了，只能提供简单的基于端口的读写路由(port based routing)和基于权重轮询的负载均衡(weighted balance)，不支持基于sql的读写分离(query based routing)和空闲优先的负载均衡(application layer balancer)【相关推荐：mysql视频教程】
以上就是mysql router是什么的详细内容。