dnsdist: backends discovery via SRV Records

[dmachard]

Hello,
I’ve noticed the new getAddressInfo() function, which is very useful for creating dynamic backends in Docker environments.

I’m wondering if a similar mechanism could be implemented based on SRV records -- allowing backend DNS servers to be defined automatically using IP address, port, priority/order, and weight from SRV responses.

If the idea makes sense and is technically feasible, I’d be happy to contribute to the implementation.

[rgacogne]

Hello!
The idea makes sense to me! The code would probably be much more complicated than the one for getAddressInfo() seems we cannot rely on getaddrinfo, but we already do something quite similar for SVCB records in dnsdist-discovery.cc, so it might be possible to reuse the existing code.