It would be nice to be able to add a device as Introducer, so it can add the other devices from the network automatically.

It would be nice to be able to add a device as Introducer, so it can add the other devices from the network automatically.

Sure, I will add the option in the device submodule.
I have not represented all options from the syncthing API, just the ones I'm using. If you want more: just request it here while this is open.

Nice! I have really wanted something like this, I thought it wasn't possible.
I'll try the PR when I have the chance.

This piece of configuration ends up in the following naming.

      folders = {
        podcasts = {
          path = "/home/palo/test-podcasts";
          id = "yvzmx-hcomd";
          devices = [ "workhorse" "schasch" "kruck" ];
        };
      };

I would be great if the attribute name would become the folder name (like it is for devices).

But apart from the folding naming the whole things works just fine.

There are a few things I would add, for example an enable flag for every device and folder entry,
this way I it's easier for me to define all my folder setups, and enable/disable them on specific computers. But I will create a pull-request once this PR is through (focus on the important parts first).

so it is a 👍

This seems to create problems.

      cert = toString <secrets/syncthing/cert.pem>;
      key = toString <secrets/syncthing/key.pem>;

error: cannot coerce a set to a string, at /var/src/nixpkgs/nixos/modules/system/boot/systemd-lib.nix:102:10
(use '--show-trace' to show detailed location information)

A recent syncthing change (I'm assuming this one) made it so that config changes made in the web interface (e.g. adding a device) don't persist across reboots. Is that intended behavior now that declarative config is possible, or should I open an issue?

Uhm, If you haven't enabled anything with a declarative option that is indeed a bug and I would be happy to fix it. there are 2 options (overrideFolder, overrideDevice) which should only be needed if any device/folder is declarative configured.
For now as a workaround you could try setting:

services.syncting.declarative = {
  overrideDevice = false;
  overrideFolder = false;
};

If you haven't enabled anything with a declarative option

I didn't change anything in the syncthing config. This happened after a nixos-rebuild switch --upgrade and then reboot.

Thanks for the workaround, I'll have to try it out. Or, perhaps even better, just move to this (awesome) new declarative config.

EDIT: Not sure if it's relevant, but here's the syncthing config I had been using:

  services.syncthing = {
    enable = true;
    user = "alex";
    openDefaultPorts = true;
    dataDir = "/home/alex/.config/syncthing";
  };

Alright, I made a PR for the fix:
#62157
sorry for the bug!