The Rocky Road of Integrating a Legacy Library with Discontinued Development Support

Kakao Pay tried to automate an existing manual process to improve work efficiency with a partner company, but ran into several technical challenges between the partner's legacy library, whose development support had been discontinued, and a modern infrastructure environment.

The key resolution process was as follows:

• Building the communication environment: To resolve the situation where the partner could not use a standard Gateway(GW), a separate GW was built, and IPSec VPN and Nginx provisioning were used to secure both security and communication simultaneously.
• Defining the API protocol: With no clear specification available, httpServletRequest logs were analyzed to confirm that the communication method in question was not REST but the SOAP protocol, and the API was implemented accordingly.
• Optimizing the K8s environment: Because the legacy JAR reads files via physical paths, a problem arose where configuration files could not be read in the Kubernetes(K8s) environment. To resolve this, an approach was applied where resources are copied to a physical path when the server starts.