Cant communicate from Docker container to Oracle server through IP SCAN

Question

I am actually running a .Net Core app in a docker container that communicates with a Oracle Database.

All runs well when I use the direct database server IP address in the connection string.

Next step was to replace the IP address with the IP SCAN, locally it works, the problem comes when the container is deployed in the Oracle Linux Server, the docker log is showing the next error:

ORA-12545: Network Transport: Unable to resolve connect hostname

Next I added the DNS parameter to the docker run command, then open the container CLI and made a ping to the IP SCAN, the packages returned succesfully, but when the app was called, same error was showed in log.

Your help will be appreciated.

Thanks in advance.

Answer 1

SCAN listeners act as load balancers, they forward the requests to the VIP addresses. Even if you use the IP address of the SCAN for connecting, it will forward your request to the VIP hostnames (which is the default behavior) and not the VIP addresses , unless configured otherwise at the database level. Your clients should to be able to resolve the name used for SCAN and the names for the VIPs too.