modules/nebula: add nebula overlay network

[siriobalmelli]

Added on a similar pattern as netbird; this is in production on our systems locally.

[Enzime]

Suggested change

	tun.device = mkOption {
	type = types.nullOr types.str;
	default = null;
	description = "Name of the tun device. Defaults to nebula.\${networkName}.";
	};
	tun.device = mkOption {
	type = types.str;
	default = "nebula.\${networkName}";
	description = "Name of the TUN device.";
	};

You'll probably also need to set defaultText

[siriobalmelli]

I'm not sure this is a good idea.

It appears that on Darwin the tunneling interface currently must be utun[0-9]+.

The parameter is not required, so I don't see an advantage to setting a default.

See https://nebula.defined.net/docs/config/tun/#tundev

[Enzime]

Suggested change

	script = ''
	exec ${cfg.package}/bin/nebula -config ${configFile}
	'';
	command = "${cfg.package}/bin/nebula -config ${configFile}";

[Enzime]

Suggested change

	enable = mkOption {
	enable = mkEnableOption {

Can you replace all the booleans that default to false and just enable logic with mkEnableOption?

[siriobalmelli]

Implementing this change yields errors like:

error: cannot coerce a set to a string: { type = «thunk»; description = "Whether this node is a lighthouse."; }

I've reverted this for now, as it seems to be a stylistic rather than operational point - and I am using this in prod.

If there are in fact compelling reasons for this change, which I'm not tracking with, please help point me in the right direction 🙏

[siriobalmelli]

Apologies for the delay, I was on leave.

Thanks for the review and suggestions, added @Enzime as co-author