MySQL Group Replication（简称MGR）是mysql官方于2016年12月推出的一个全新的高可用与高扩展的解决方案。MySQL组复制提供了高可用、高扩展、高可靠的MySQL集群服务。
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高一致性，基于原生复制及paxos协议的组复制技术，并以插件的方式提供，提供一致数据安全保证；
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高容错性，只要不是大多数节点坏掉就可以继续工作，有自动检测机制，当不同节点产生资源争用冲突时，不会出现错误，按照先到者优先原则进行处理，并且内置了自动化脑裂防护机制；
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高扩展性，节点的新增和移除都是自动的，新节点加入后，会自动从其他节点上同步状态，直到新节点和其他节点保持一致，如果某节点被移除了，其他节点自动更新组信息，自动维护新的组信息；
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高灵活性，有单主模式和多主模式，单主模式下，会自动选主，所有更新操作都在主上进行；多主模式下，所有server都可以同时处理更新操作。
Docker 是一个开源的引擎，可以轻松的为任何应用创建一个轻量级的、可移植的、自给自足的容器。开发者在笔记本上编译测试通过的容器可以批量地在生产环境中部署，包括VMs（虚拟机）、bare metal、OpenStack 集群和其他的基础应用平台。
1.安装Docker及配置MGR
从官方的docker store中拉取MySQL镜像，大约只需要几分钟时间，完毕以后，可以通过docker images命令来查看。
[root@iz2zec57gfl6i9vbtdksl1z ~]# yum install -y docker
[root@iz2zec57gfl6i9vbtdksl1z ~]# docker pull mysql:5.7.17
[root@iz2zec57gfl6i9vbtdksl1z ~]# docker images;
REPOSITORY TAG IMAGE ID CREATED SIZE
docker.io/mysql 5.7.17 9546ca122d3a 4 months ago 406.9 MB
现在我们已经有了docker镜像，然后我们设计如下的目录结构，将三个数据库的数据文件映射到宿主机。
# mkdir /Users/Kamus/mysql_data
#
mkdir /Users/Kamus/mysql_data/s1-docker
#
mkdir /Users/Kamus/mysql_data/s2-docker
#
mkdir /Users/Kamus/mysql_data/s3-docker
由于目标是能运行MGR集群，那么是有一部分数据库初始化参数要额外设置的，而docker容器中的my.cnf内容无法改动，所以我们再设计一个专门的目录用来存储所有数据库的my.cnf文件。
# mkdir /Users/Kamus/mysql_data/conf.d
# mkdir /Users/Kamus/mysql_data/conf.d/s1-docker
# mkdir /Users/Kamus/mysql_data/conf.d/s2-docker
# mkdir /Users/Kamus/mysql_data/conf.d/s3-docker
网络网段的设置，只能使用用户指定的IP网段
[root@iz2zec57gfl6i9vbtdksl1z mysql_data]# docker network ls
NETWORK ID NAME DRIVER SCOPE
02cf0f7c8806 bridge bridge local
74ea9186efd3 host host local
d25ca440e9f6 none null local
[root@iz2zec57gfl6i9vbtdksl1z mysql_data]# docker run --detach --memory=500m --memory-swap=1g --hostname=mysql-mgr-server1 --net=bridge --ip=172.18.0.2 --add-host mysql-mgr-server1:172.18.0.3 --add-host mysql-mgr-server3:172.18.0.4 --publish 3307:3306 --volume=/mnt/mysql_data/conf.d/s1-docker/:/etc/mysql/conf.d --volume=/mnt/mysql_data/s1-docker:/var/lib/mysql --name=s1-docker -d docker.io/mysql:5.7.17
33b5e2660b080a74f056ad50a061b56d53aeede8b3cbb3673712cc018046e705
/usr/bin/docker-current: Error response from daemon: User specified IP address is supported on user defined networks only.
[root@iz2zec57gfl6i9vbtdksl1z mysql_data]# docker network create --subnet=172.19.0.0/16 b1
[root@iz2zec57gfl6i9vbtdksl1z ~]# docker network ls
NETWORK ID NAME DRIVER SCOPE
3e9fad4158b4 b1 bridge local
02cf0f7c8806 bridge bridge local
74ea9186efd3 host host local
d25ca440e9f6 none null local
因为我们设计了容器启动时候会拥有不同的IP地址，因此在容器中运行的MySQL实例的初始化参数中关于MGR的部分也需要指定这些IP地址。以下是my.cnf文件的设置内容。
[mysqld]
datadir=/var/lib/mysql
pid-file=/var/run/mysqld/mysqld.pid
port=3306
socket=/var/run/mysqld/mysqld.sock
server_id=2
gtid_mode=ON
enforce_gtid_consistency=ON
master_info_repository=TABLE
relay_log_info_repository=TABLE
binlog-format=ROW
binlog_checksum=NONE
log-slave-updates=1
log_bin=binlog
relay-log=bogon-relay-bin
# Group Replication
transaction_write_set_extraction = XXHASH64
loose-group_replication_group_name="aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa"
loose-group_replication_start_on_boot = off
loose-group_replication_local_address = '172.19.0.2:33061'
loose-group_replication_group_seeds ='172.19.0.2:33061,172.19.0.3:33061,172.19.0.4:33061'
loose-group_replication_bootstrap_group = off
对于第一个容器s1-container会使用到的my.cnf文件，这个参数为：
loose-group_replication_local_address="172.19.0.1:33061"
对于第二个容器s2-container会使用到的my.cnf文件，这个参数为：
loose-group_replication_local_address="172.19.0.3:33061"
对于第三个容器s3-container会使用到的my.cnf文件，这个参数为：
loose-group_replication_local_address="172.19.0.4:33061"
2.启动docker镜像有关mysql容器：
运行三个docker容器的完整命令如下：
[root@iz2zec57gfl6i9vbtdksl1z ~]# docker run --detach --memory=500m --memory-swap=1g --hostname=mysql-mgr-server3 --net=b1 --ip=172.19.0.4 --add-host mysql-mgr-server1:172.19.0.2 --add-host mysql-mgr-server2:172.19.0.3 --publish 3309:3306 --volume=/mnt/mysql_data/conf.d/s3-docker/:/etc/mysql/conf.d --volume=/mnt/mysql_data/s3-docker:/var/lib/mysql --name=s3-docker -e MYSQL_ROOT_PASSWORD=123456 -d docker.io/mysql:5.7.17
[root@iz2zec57gfl6i9vbtdksl1z ~]# docker run --detach --memory=500m --memory-swap=1g --hostname=mysql-mgr-server2 --net=b1 --ip=172.19.0.3 --add-host mysql-mgr-server1:172.19.0.2 --add-host mysql-mgr-server3:172.19.0.4 --publish 3308:3306 --volume=/mnt/mysql_data/conf.d/s2-docker/:/etc/mysql/conf.d --volume=/mnt/mysql_data/s2-docker:/var/lib/mysql --name=s2-docker -e MYSQL_ROOT_PASSWORD=123456 -d docker.io/mysql:5.7.17
[root@iz2zec57gfl6i9vbtdksl1z ~]# docker run --detach --memory=500m --memory-swap=1g --hostname=mysql-mgr-server1 --net=b1 --ip=172.19.0.2 --add-host mysql-mgr-server1:172.19.0.3 --add-host mysql-mgr-server3:172.19.0.4 --publish 3307:3306 --volume=/mnt/mysql_data/conf.d/s1-docker/:/etc/mysql/conf.d --volume=/mnt/mysql_data/s1-docker:/var/lib/mysql --name=s1-docker -e MYSQL_ROOT_PASSWORD=123456 -d docker.io/mysql:5.7.17
查看是否启动mysql成功：
[root@iz2zec57gfl6i9vbtdksl1z ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
30396bcd7ffb docker.io/mysql:5.7.17 "docker-entrypoint.sh" 7 hours ago Up 7 hours 0.0.0.0:3309->3306/tcp s3-docker
6644ab2fa9ae docker.io/mysql:5.7.17 "docker-entrypoint.sh" 7 hours ago Up 7 hours 0.0.0.0:3308->3306/tcp s2-docker
7ca53c437c5a docker.io/mysql:5.7.17 "docker-entrypoint.sh" 8 hours ago Up 8 hours 0.0.0.0:3307->3306/tcp s1-docker
报错时在宿主机查看日志：
[root@iz2zec57gfl6i9vbtdksl1z conf.d]# docker logs <CONTAINER ID>
通过如下命令登录到Docker容器的操作系统中，再进入MySQL实例，启动MGR。我们目前设置的是Single Primary模式的MGR，先启动第一个Primary实例。
[root@iz2zec57gfl6i9vbtdksl1z ~]# docker exec -it s1-docker bash
root@mysql-mgr-server1:/# mysql -uroot -p123456
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 116
Server version: 5.7.17-log MySQL Community Server (GPL)
Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> SET SQL_LOG_BIN=0;
Query OK, 0 rows affected (0.00 sec)
mysql> CREATE USER rpl_user@'%';
Query OK, 0 rows affected (0.00 sec)
mysql> GRANT REPLICATION SLAVE ON *.* TO rpl_user@'%' IDENTIFIED BY 'rpl_pass';
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.00 sec)
mysql> SET SQL_LOG_BIN=1;
Query OK, 0 rows affected (0.00 sec)
mysql> CHANGE MASTER TO MASTER_USER='rpl_user', MASTER_PASSWORD='rpl_pass' FOR CHANNEL 'group_replication_recovery';
Query OK, 0 rows affected, 2 warnings (0.03 sec)
mysql> INSTALL PLUGIN group_replication SONAME 'group_replication.so';
Query OK, 0 rows affected (0.01 sec)
mysql> SET GLOBAL group_replication_bootstrap_group=ON;
Query OK, 0 rows affected (0.01 sec)
mysql> START GROUP_REPLICATION;
Query OK, 0 rows affected (0.01 sec)
mysql> SET GLOBAL group_replication_bootstrap_group=OFF;
Query OK, 0 rows affected (0.01 sec)
mysql> SELECT * FROM performance_schema.replication_group_members;
+---------------------------+--------------------------------------+-------------------+-------------+--------------+
| CHANNEL_NAME | MEMBER_ID | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------------+-------------+--------------+
| group_replication_applier | d79c04bf-87a3-11e7-865f-0242ac130002 | mysql-mgr-server1 | 3306 | ONLINE
+---------------------------+--------------------------------------+-------------------+-------------+--------------+
3 rows in set (0.00 sec)
mysql>
启动第二个只读实例：
[root@iz2zec57gfl6i9vbtdksl1z ~]# docker exec -it s2-docker bash
root@mysql-mgr-server2:/# mysql -uroot -p123456
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.7.17-log MySQL Community Server (GPL)
Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> SET SQL_LOG_BIN=0;
Query OK, 0 rows affected (0.00 sec)
mysql> CREATE USER rpl_user@'%';
Query OK, 0 rows affected (0.00 sec)
mysql> GRANT REPLICATION SLAVE ON *.* TO rpl_user@'%' IDENTIFIED BY 'rpl_pass';
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.00 sec)
mysql> SET SQL_LOG_BIN=1;
Query OK, 0 rows affected (0.00 sec)
mysql> CHANGE MASTER TO MASTER_USER='rpl_user', MASTER_PASSWORD='rpl_pass' FOR CHANNEL 'group_replication_recovery';
Query OK, 0 rows affected, 2 warnings (0.03 sec)
mysql> INSTALL PLUGIN group_replication SONAME 'group_replication.so';
Query OK, 0 rows affected (0.01 sec)
mysql> START GROUP_REPLICATION;
Query OK, 0 rows affected (5.52 sec)
mysql> SELECT * FROM performance_schema.replication_group_members;
+---------------------------+--------------------------------------+-------------------+-------------+--------------+
| CHANNEL_NAME | MEMBER_ID | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------------+-------------+--------------+
| group_replication_applier | d79c04bf-87a3-11e7-865f-0242ac130002 | mysql-mgr-server1 | 3306 | ONLINE |
| group_replication_applier | f7127f84-87a5-11e7-97af-0242ac130003 | mysql-mgr-server2 | 3306 | ONLINE |
+---------------------------+--------------------------------------+-------------------+-------------+--------------+
2 rows in set (0.00 sec)
启动第三个只读实例：
[root@iz2zec57gfl6i9vbtdksl1z ~]# docker exec -it s3-docker bash
root@mysql-mgr-server3:/# mysql -uroot -p123456
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.7.17-log MySQL Community Server (GPL)
Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> SET SQL_LOG_BIN=0;
Query OK, 0 rows affected (0.00 sec)
mysql> CREATE USER rpl_user@'%';
Query OK, 0 rows affected (0.00 sec)
mysql> GRANT REPLICATION SLAVE ON *.* TO rpl_user@'%' IDENTIFIED BY 'rpl_pass';
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.00 sec)
mysql> SET SQL_LOG_BIN=1;
Query OK, 0 rows affected (0.00 sec)
mysql> CHANGE MASTER TO MASTER_USER='rpl_user', MASTER_PASSWORD='rpl_pass' FOR CHANNEL 'group_replication_recovery';
Query OK, 0 rows affected, 2 warnings (0.03 sec)
mysql> INSTALL PLUGIN group_replication SONAME 'group_replication.so';
Query OK, 0 rows affected (0.01 sec)
mysql> START GROUP_REPLICATION;
Query OK, 0 rows affected (0.01 sec)
mysql> SELECT * FROM performance_schema.replication_group_members;
+---------------------------+--------------------------------------+-------------------+-------------+--------------+
| CHANNEL_NAME | MEMBER_ID | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------------+-------------+--------------+
| group_replication_applier | d79c04bf-87a3-11e7-865f-0242ac130002 | mysql-mgr-server1 | 3306 | ONLINE |
| group_replication_applier | f7127f84-87a5-11e7-97af-0242ac130003 | mysql-mgr-server2 | 3306 | ONLINE |
| group_replication_applier | feeee99d-87a5-11e7-97cb-0242ac130004 | mysql-mgr-server3 | 3306 | ONLINE |
+---------------------------+--------------------------------------+-------------------+-------------+--------------+
3 rows in set (0.00 sec)
start group_replication可能一些问题
mysql> START GROUP_REPLICATION;
ERROR 3092 (HY000): The server is not configured properly to be an active member of the group. Please see more details on error log.
解决办法：回到宿主机中查看错误日志：
[root@iz2zec57gfl6i9vbtdksl1z ~]# docker logs -f -t --tail=10 <CONTAINER ID >
问题1：
2017-08-23T02:24:51.177878000Z 2017-08-23T02:24:51.175681Z 0 [Warning] Plugin group_replication reported: '[GCS] Connection attempt from IP address 172.19.0.4 refused. Address is not in the IP whitelist.'
2017-08-23T02:24:51.178024000Z 2017-08-23T02:24:51.175721Z 0 [ERROR] Plugin group_replication reported: '[GCS] Error connecting to the local group communication engine instance.'
2017-08-23T02:24:51.178176000Z 2017-08-23T02:24:51.175728Z 0 [Note] Plugin group_replication reported: 'state 4257 action xa_exit'
2017-08-23T02:24:51.178312000Z 2017-08-23T02:24:51.175798Z 0 [Note] Plugin group_replication reported: 'Exiting xcom thread'
2017-08-23T02:24:52.209910000Z 2017-08-23T02:24:52.209376Z 0 [ERROR] Plugin group_replication reported: '[GCS] The member was unable to join the group. Local port: 33061'
2017-08-23T02:25:51.176542000Z 2017-08-23T02:25:51.175539Z 3 [ERROR] Plugin group_replication reported: 'Timeout on wait for view after joining group'
2017-08-23T02:25:51.176898000Z 2017-08-23T02:25:51.175647Z 3 [Note] Plugin group_replication reported: 'Requesting to leave the group despite of not being a member'
2017-08-23T02:25:51.177142000Z 2017-08-23T02:25:51.175676Z 3 [ERROR] Plugin group_replication reported: '[GCS] The member is leaving a group without being on one.'
2017-08-23T02:25:51.179057000Z 2017-08-23T02:25:51.175896Z 3 [Note] Plugin group_replication reported: 'auto_increment_increment is reset to 1'
2017-08-23T02:25:51.179354000Z 2017-08-23T02:25:51.175905Z 3 [Note] Plugin group_replication reported: 'auto_increment_offset is reset to 1'
2017-08-23T02:25:51.179567000Z 2017-08-23T02:25:51.177979Z 15 [Note] Error reading relay log event for channel 'group_replication_applier': slave SQL thread was killed
2017-08-23T02:25:51.185216000Z 2017-08-23T02:25:51.184778Z 12 [Note] Plugin group_replication reported: 'The group replication applier thread was killed'
解决：
mysql> set global group_replication_ip_whitelist='172.19.0.0/24' ;
Query OK, 0 rows affected (0.00 sec)
问题2：
2017-08-23T02:29:34.592161000Z 2017-08-23T02:29:34.590561Z 0 [Note] Plugin group_replication reported: 'state 4277 action xa_complete'
2017-08-23T02:29:34.592311000Z 2017-08-23T02:29:34.590696Z 0 [Note] Plugin group_replication reported: 'new state x_run'
2017-08-23T02:29:35.691341000Z 2017-08-23T02:29:35.689373Z 0 [ERROR] Plugin group_replication reported: 'This member has more executed transactions than those present in the group. Local transactions: feeee99d-87a5-11e7-97cb-0242ac130004:1-5 > Group transactions: aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa:1-8,
2017-08-23T02:29:35.691504000Z d79c04bf-87a3-11e7-865f-0242ac130002:1-5,
2017-08-23T02:29:35.691652000Z f7127f84-87a5-11e7-97af-0242ac130003:1-5'
2017-08-23T02:29:35.691806000Z 2017-08-23T02:29:35.689397Z 0 [ERROR] Plugin group_replication reported: 'The member contains transactions not present in the group. The member will now exit the group.'
2017-08-23T02:29:35.691957000Z 2017-08-23T02:29:35.689401Z 0 [Note] Plugin group_replication reported: 'To force this member into the group you can use the group_replication_allow_local_disjoint_gtids_join option'
解决：
mysql> show variables like 'group_replication_allow_local_disjoint_gtids_join';
+---------------------------------------------------+-------+
| Variable_name | Value |
+---------------------------------------------------+-------+
| group_replication_allow_local_disjoint_gtids_join | OFF |
+---------------------------------------------------+-------+
1 row in set (0.00 sec)
mysql> set global group_replication_allow_local_disjoint_gtids_join=1;
Query OK, 0 rows affected (0.00 sec)
mysql> START GROUP_REPLICATION;
Query OK, 0 rows affected (2.12 sec)
测试：
在s1-docker创建库test，表test1
mysql> create database test
1 row in set (0.00 sec)
mysql> use test;
Database changed
mysql> create table test1 (id int primary key,name varchar(12));
Query OK, 0 rows affected (0.05 sec)
mysql> insert into test1 values (123,'abc');
Query OK, 1 row affected (0.00 sec)
mysql> select * from test1;
+-----+------+
| id | name |
+-----+------+
| 111 | aaa |
+-----+------+
2 rows in set (0.00 sec)
mysql>
在s2-docker查看是否同步：
root@mysql-mgr-server2:/var/lib/mysql# mysql -uroot -p123456
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 117
Server version: 5.7.17-log MySQL Community Server (GPL)
Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> use test;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> select * from test1;
+-----+------+
| id | name |
+-----+------+
| 111 | aaa |
+-----+------+
2 rows in set (0.00 sec)
在s3-docker查看是否同步：
root@mysql-mgr-server3:/var/lib/mysql# mysql -uroot -p123456
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 119
Server version: 5.7.17-log MySQL Community Server (GPL)
Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> use test;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> select * from test1;
+-----+------+
| id | name |
+-----+------+
| 111 | aaa |
+-----+------+
2 rows in set (0.00 sec)
主要参考mysql官方文档：
部分参考文档来源：
