Spring Boot JPA - configuring auto reconnect

Question

I have a nice little Spring Boot JPA web application. It is deployed on Amazon Beanstalk and uses an Amazon RDS for persisting data. It is however not used that often and therefore fails after a while with this kind of exception:

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet successfully received from the server was 79,870,633 milliseconds ago.
The last packet sent successfully to the server was 79,870,634 milliseconds ago. is longer than the server configured value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property 'autoReconnect=true' to avoid this problem.

I am not sure how to configure this setting and can not find information on it on http://spring.io (a very good site though). What are some ideas or pointers to information?

Answer 1

I assume that boot is configuring the DataSource for you. In this case, and since you are using MySQL, you can add the following to your application.properties up to 1.3

spring.datasource.testOnBorrow=true
spring.datasource.validationQuery=SELECT 1

As djxak noted in the comment, 1.4+ defines specific namespaces for the four connections pools Spring Boot supports: tomcat, hikari, dbcp, dbcp2 (dbcp is deprecated as of 1.5). You need to check which connection pool you are using and check if that feature is supported. The example above was for tomcat so you'd have to write it as follows in 1.4+:

spring.datasource.tomcat.testOnBorrow=true 
spring.datasource.tomcat.validationQuery=SELECT 1

Note that the use of autoReconnect is not recommended:

The use of this feature is not recommended, because it has side effects related to session state and data consistency when applications don't handle SQLExceptions properly, and is only designed to be used when you are unable to configure your application to handle SQLExceptions resulting from dead and stale connections properly.