mysql两主一从的搭建示例代码：
[root@localhost etc]# cat my.cnf# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/8.0/en/server-configuration-defaults.html
[mysqld]
#
# Remove leading # and set to the amount of RAM for the most important data
# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
# innodb_buffer_pool_size = 128M
#
# Remove the leading "# " to disable binary logging
# Binary logging captures changes between backups and is enabled by
# default. It's default setting is log_bin=binlog
# disable_log_bin
#
# Remove leading # to set options mainly useful for reporting servers.
# The server defaults are faster for transactions and fast SELECTs.
# Adjust sizes as needed, experiment to find the optimal values.
# join_buffer_size = 128M
# sort_buffer_size = 2M
# read_rnd_buffer_size = 2M
#
# Remove leading # to revert to previous value for default_authentication_plugin,
# this will increase compatibility with older clients. For background, see:
# https://dev.mysql.com/doc/refman/8.0/en/server-system-variables.html#sysvar_default_authentication_plugin
# default-authentication-plugin=mysql_native_password
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
[mysqld_muliti]
mysqld=/usr/bin/mysqld_safe
mysqladmin=/usr/bin/mysqladmin
user=root
password=123456
[mysqld178]
port=3306
datadir=/var/lib/mysqla
pid-file=/var/lib/mysqla/mysqld.pid
socket=/var/lib/mysqla/mysql.sock
user=mysql
server-id=3
[mysqld179]
port=3307
datadir=/var/lib/mysqlb
pid-file=/var/lib/mysqlb/mysqld.pid
socket=/var/lib/mysqlb/mysql.sock
user=mysql
server-id=3