[Cloud Z DB] Disconnection occurs when using Cloud Z DB in AWS environment

This issue may occur when connecting using a Private IP. 

he Private IP of Cloud Z DB in the AWS environment uses AWS Network Load Balancer (NLB).

The AWS NLB (Network Load Balancer) service performs a connection idle timeout check and closes connections that are not idle.

(https://docs.aws.amazon.com/elasticloadbalancing/latest/network/network-load-balancers.html#connection-idle-timeout)

When using a Private IP:

Since the idle timeout value of AWS NLB is 350 seconds, the application must perform a health check on the connection at intervals shorter than 350 seconds to prevent the connection from becoming idle.

For example, this can be prevented by configuring the idle-timeout setting in Hikari to a value shorter than 350 seconds.

Additionally, within a K8S Cluster, it is possible to connect using the Cluster IP instead of the Private IP.