OpenCluster init new gorm client cluster with mysql database.

Enum present a selectable of value which store in database in int mode, but in application is string mode, this will translate automatically.

IPV4 present a selectable of ipv4 address which store in database in int mode, but in application is ipv4 mode, this will translate automatically.

ConnectionOption is helper function to modify database pool options.

StringArray present a slice of array which store in database in string mode, but in application is string slice mode, this will translate automatically.