MySQL master-slave connection prompt of docker: communications link failure

In use today Apache ShardingSphere Realize the database read-write separation function , The connection is based on Docker Of MySQL5.7 Master-slave IP.SpringBoot The program prompts the following error message ：

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException:Communications link failure

Reason for the error ：MySQL The service was disconnected after a long period of inactivity , The first request after disconnection will throw this exception

Cause analysis ：

1、 Since it was disconnected after a long time of disconnection , The time should be settable , Or now mysql Using the default value

2、 How to view the current time value , And how to modify based on docker Service started MySQL.

View the default values ：

1、 Use Native For MySQL Client tools , Execute the following instructions ：show variables like '%timeout%'

Parameter description ：

1)interactive_timeout:
  Parameter meaning ： The number of seconds the server waits for activity before shutting down the interactive connection . The interactive client is defined as mysql_real_connect() Use in CLIENT_INTERACTIVE Option client .
  Parameter default ：28800 second （8 Hours ）
 
2)wait_timeout:
  Parameter meaning ： The number of seconds the server waits for activity before shutting down non interactive connections . When the thread starts , According to the global wait_timeout Value or global interactive_timeout Value initializes the session wait_timeout value , Depends on the client type (mysql_real_connect() Connection options for CLIENT_INTERACTIVE Definition ).
Parameter default ：28800 second （8 Hours ）

reminder ： stay MySQL4 And below , Can pass autoReconnect=true Configure properties to solve the problem of automatic connection recovery , If it is MySQL5 And above , Must pass System parameters to control .

Conclusion ： To modify , You need to modify both variables at the same time

Connection time value range ： stay windows Environment ：1-2147483s,

                              stay Linux Environment ：1-31536000s

Docker Modify the MySQL：MySQL5.7 stay Docker The core configuration file under , It is realized by hanging the roll , So we just need to modify Docker The address of the mount directory where the host is located , Modify the corresponding file .

docker start-up MySQL5.7:

 docker run -p 3307:3306 --name mysql-master \
  -v /usr/local/mysql-master/log:/var/log/mysql \
  -v /usr/local/mysql-master/data:/var/lib/mysql \
  -v  /usr/local/mysql-master/conf:/etc/mysql \
  -e MYSQL_ROOT_PASSWORD=root \
  -d mysql:5.7

 MySQL5.7 The file directory address of the host where the configuration file is located ：/usr/local/mysql-master/conf

stay my.cnf file , Add timeout configuration .

[mysqld]
 ##  Set up server_id, You need to be unique in the same LAN 
 server_id=101
 ##  Specify the name of the database that does not need to be synchronized 
 binlog-ignore-db=mysql
 ##  Turn on binary log function 
 log-bin=mall-mysql-bin
 ##  Set the memory size of binary log （ Business ）
 binlog_cache_size=1M
 ##  Set the binary log format to use （mixed,statement,row）
 binlog_format=mixed
 ##  Binary log expiration cleanup time . The default value is 0, Does not automatically clean up .
 expire_logs_days=7
 ##  Skip all errors encountered in master-slave replication or errors of the specified type , avoid slave End copy interrupt .
 ##  Such as ：1062 An error is a duplicate of some primary keys ,1032 The error is because the master-slave database data is inconsistent 
 slave_skip_errors=1062
 ##  Set timeout 
 wait_timeout=1814400
 interactive_timeout=1814400

Restart Docker Service and its restart MySQL service , Then check the connection time configuration ：