I don't think so? The unit generated by NixOS modules is way different than the upstream one (e.g. upstream assumes /usr/sbin/tailscaled as the path).

Do you have an example of a module that reuses an upstream service config that I can pull from?

Do you have an example of a module that reuses an upstream service config that I can pull from?

Certainly. I recently switched dnsdist over to use the upstream service.

A couple points to note:

• there is a bug in NixOS currently so you'll have to include wantedBy = [ "multi-user.target" ]; in your module
• tailscale upstream should better package their software to not include hard coded paths, but instead utilize the install prefix from the build system
• until upstream has corrected the hard coded path it is easy enough to override ExecStart - just be sure to include an empty element in the list to erase all previous entries (see systemd docs on ExecStart if you're not familiar) like so: ExecStart = [ ”” "${pkgs.tailscale}/bin/tailscale --state=/var/lib/tailscale/tailscaled.state --socket=/run/tailscale/tailscaled.sock --port $PORT $FLAGS ] (and make sure you set systemd.services.tailscale.environment.PORT = toString cfg.port;)
• if you want to improve the systemd unit the best place to do that is upstream (though doing it in the module can be acceptable as well)

It looks relatively straight forward to use the upstream unit, but if you run into any issues I would be more than happy to help.

I'm also the maintainer of the upstream unit, so using it as close to as-is as possible SGTM. We don't have a build system upstream that handles install prefixes though, the systemd unit is just what we use to generate .deb and .rpm packages. That said, I can adjust things in the tailscale derivation rather than the nixos module, so that the module doesn't need any further tweaks. I'll update this PR with fixes to the package and module, thanks for the guidance!

@aanderse Ready for another look. The package now includes the systemd unit (with correct paths and removed impure /etc reference), and the module is the minimum deviation from that to make the module parameter work. Tested successfully on my own NixOS systems.

Thanks @danderson 🎉