从已有的组复制搭建InnoDB Cluster环境

本文描述了如何基于已有的MySQL Group Replication，创建一个 Innodb cluster。

1. 已有的MySQL Group Replication 环境信息

ip地址	主机名	server_id
172.17.84.71	mysql001	1
172.17.84.72	mysql002	2
172.17.84.73	mysql003	3

查看组复制当前状态

mysql> SELECT * FROM performance_schema.replication_group_members;
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| CHANNEL_NAME              | MEMBER_ID                            | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE |
+---------------------------+--------------------------------------+-------------+-------------+--------------+
| group_replication_applier | 80af8598-1520-11e7-a8b9-08002730b4d8 | mysql001    |        3306 | ONLINE       |
| group_replication_applier | 8abf4eab-1521-11e7-9cc9-080027b95fc4 | mysql002    |        3306 | ONLINE       |
| group_replication_applier | dcd3068d-15bc-11e7-b264-080027dad0d6 | mysql003    |        3306 | ONLINE       |

2. Yum 安装MySQL Shell

wget https://dev.mysql.com/get/mysql57-community-release-el7-10.noarch.rpm
rpm -ivh mysql57-community-release-el7-10.noarch.rpm
yum install mysql-shell -y

3. 创建cluster

通过指定 adoptFromGR option，使用dba.createCluster()

mysqlsh --uri root@172.17.84.71:3306
mysql-js> var cluster = dba.createCluster('prodCluster', {adoptFromGR: true});
A new InnoDB cluster will be created on instance 'root@172.17.84.7:3306'.
Creating InnoDB cluster 'prodCluster' on 'root@172.17.84.72:3306'...
Adding Seed Instance...
Cluster successfully created. Use Cluster.addInstance() to add MySQL instances.
At least 3 instances are needed for the cluster to be able to withstand up to
one server failure.

查看cluster状态

mysql-js> var cluster=dba.getCluster()
mysql-js> cluster.status()
{
    "clusterName": "prodCluster",
    "defaultReplicaSet": {
        "name": "default",
        "primary": "172.17.84.71:3306",
        "status": "OK",
        "statusText": "Cluster is ONLINE and can tolerate up to ONE failure.",
        "topology": {
            "172.17.84.71:3306": {
                "address": "172.17.84.71:3306",
                "mode": "R/W",
                "readReplicas": {},
                "role": "HA",
                "status": "ONLINE"
            },
            "mysql002:3306": {
                "address": "mysql002:3306",
                "mode": "R/O",
                "readReplicas": {},
                "role": "HA",
                "status": "ONLINE"
            },
            "mysql003:3306": {
                "address": "mysql003:3306",
                "mode": "R/O",
                "readReplicas": {},
                "role": "HA",
                "status": "ONLINE"
            }
        }
    }
}

4. 持久化配置文件

对于已经在cluster中的实例，可以持久化cluster的配置

1	dba.configureLocalInstance(root@localhost:3306)

查看配置文件的变化my.cnf

5.简单测试Failover

关闭mysql001实例

1	systemctl stop mysqld

重启mysql001实例

1	systemctl start mysqld

查看cluster状态,发现Primary Master已经切换到mysql002

mysql-js> cluster.status()
{
    "clusterName": "prodCluster",
    "defaultReplicaSet": {
        "name": "default",
        "primary": "172.17.84.72:3306",
        "status": "OK",
        "statusText": "Cluster is ONLINE and can tolerate up to ONE failure.",
        "topology": {
            "172.17.84.72:3306": {
                "address": "172.17.84.72:3306",
                "mode": "R/W",
                "readReplicas": {},
                "role": "HA",
                "status": "ONLINE"
            },
            "mysql001:3306": {
                "address": "mysql001:3306",
                "mode": "R/O",
                "readReplicas": {},
                "role": "HA",
                "status": "ONLINE"
            },
            "mysql003:3306": {
                "address": "mysql003:3306",
                "mode": "R/O",
                "readReplicas": {},
                "role": "HA",
                "status": "ONLINE"
            }
        }
    }
}

6.createCluster语法

mysql-js> dba.help(createCluster());
ReferenceError: createCluster is not defined
mysql-js> dba.help('createCluster');
Creates a MySQL InnoDB cluster.
SYNTAX
  <Dba>.createCluster(name[, options])
WHERE
  name: The name of the cluster object to be created.
  options: Dictionary with options that modify the behavior of this function.
DESCRIPTION
Creates a MySQL InnoDB cluster taking as seed instance the active global
session.
The options dictionary can contain the next values:
 - clusterAdminType: defines the type of management to be done on the cluster
   instances.
 - multiMaster: boolean value used to define an InnoDB cluster with multiple
   writable instances.
 - force: boolean, confirms that the multiMaster option must be applied.
 - adoptFromGR: boolean value used to create the InnoDB cluster based on
   existing replication group.
 - memberSslMode: SSL mode used to configure the members of the cluster.
 - ipWhitelist: The list of hosts allowed to connect to the instance for group
   replication.
The values for clusterAdminType options include: local, manual, guided or ssh,
however, at the moment only local is supported and is used as default value if
this attribute is not specified.
A InnoDB cluster may be setup in two ways:
 - Single Master: One member of the cluster allows write operations while the
   rest are in read only mode.
 - Multi Master: All the members in the cluster support both read and write
   operations.
By default this function create a Single Master cluster, use the multiMaster
option set to true if a Multi Master cluster is required.
The memberSslMode option supports these values:
 - REQUIRED: if used, SSL (encryption) will be enabled for the instances to
   communicate with other members of the cluster
 - DISABLED: if used, SSL (encryption) will be disabled
 - AUTO: if used, SSL (encryption) will be enabled if supported by the
   instance, otherwise disabled
If memberSslMode is not specified AUTO will be used by default.
The ipWhitelist format is a comma separated list of IP addresses or subnet CIDR
notation, for example: 192.168.1.0/24,10.0.0.1. By default the value is set to
AUTOMATIC, allowing addresses from the instance private network to be
automatically set for the whitelist.