If you are asking for project setup, I think I got it working to do the least effort to get an API described and implemented.

https://github.com/jmaister/taronja-gateway

Take a look to the api/ folder where there is an OpenAPI spec, and to the Makefile ('gen' task). Most of the code is generated by OpenAPI generators one for the server implementation and one for the TypeScript SDK that runs in the client (browser)