$ mysql -u root -p
> create user 'zabbix_monitor'@'%' identified by 'zabbix123';
> grant usage,replication client,process,show databases,show view on *.* to 'zabbix_monitor';

$ cd /etc/zabbix/zabbix_agentd.d/
$ vim template_db_mysql.conf

#template_db_mysql.conf created by Zabbix for "Template DB MySQL" and Zabbix 4.2
#For OS Linux: You need create .my.cnf in zabbix-agent home directory (/var/lib/zabbix by default) 
#For OS Windows: You need add PATH to mysql and mysqladmin and create my.cnf in %WINDIR%\my.cnf,C:\my.cnf,BASEDIR\my.cnf https://dev.mysql.com/doc/refman/5.7/en/option-files.html
#The file must have three strings:
#[client]
#user='zbx_monitor'
#password='<password>'
#
UserParameter=mysql.ping[*], mysqladmin -h"$1" -P"$2" ping
UserParameter=mysql.get_status_variables[*], mysql -h"$1" -P"$2" -sNX -e "show global status"
UserParameter=mysql.version[*], mysqladmin -s -h"$1" -P"$2" version
UserParameter=mysql.db.discovery[*], mysql -h"$1" -P"$2" -sN -e "show databases"
UserParameter=mysql.dbsize[*], mysql -h"$1" -P"$2" -sN -e "SELECT COALESCE(SUM(DATA_LENGTH + INDEX_LENGTH),0) FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA='$3'"
UserParameter=mysql.replication.discovery[*], mysql -h"$1" -P"$2" -sNX -e "show slave status"
UserParameter=mysql.slave_status[*], mysql -h"$1" -P"$2" -sNX -e "show slave status"

$ mkdir /var/lib/zabbix
$ vim /var/lib/zabbix/.my.cnf

[client]
user=zabbix_monitor
password=zabbix123

13633:20200815:135343.160 item "Jblog:mysql.connection_errors_internal.rate" became not supported: Preprocessing failed for: ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock...
1. Failed: cannot extract XML value with xpath "/resultset/row[field/text()='Connection_errors_internal']/field[@name='Value']/text()": cannot parse xml value: Start tag expected, '<' not found
noname.xml:1: parser error : Start tag expected, '<' not found
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib

注重这点就可以了
Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock...

$ vim /var/lib/zabbix/.my.cnf

[client]
user=zabbix_monitor
password=zabbix123
socket=/tmp/mysql.sock