The Pain and Peculiarity of NixOS Networking with systemd-networkd

Setting up networking on NixOS with systemd-networkd should, in theory, be a straightforward and declarative process. Just define your network configurations in Nix, let systemd-networkd handle the interfaces, and enjoy a seamless, reproducible setup. But reality hits differently. My journey with systemd-networkd on NixOS has been a mix of frustration, debugging marathons, and the occasional victory that feels more like luck than mastery. In this article, I’ll go over some of the quirks I’ve encountered, the pitfalls that made me question my sanity, and the workarounds that (sometimes) saved the day.