Systemd configuration options and list types

[Bert-Proesmans]

I ran the topology builder on my configurations and the code throws an error processing option systemd.networks.networks..matchConfig.MACAddress; value is list instead of expected string.

The error is thrown specifically on line 82;

nix-topology/nixos/extractors/systemd-network.nix

Lines 75 to 92 in 1826fe5

	# FIXME: TODO renameInterfacesByMac is not a standard option! It's not an issue here but should proabaly not be used anyway.
	extraMacToName = listToAttrs (mapAttrsToList (k: v: nameValuePair v k) (config.networking.renameInterfacesByMac or {}));
	macToName = recursiveUpdate linkMacToName extraMacToName;
	nameFromMac =
	optional (network ? matchConfig.MACAddress && macToName ? ${network.matchConfig.MACAddress})
	macToName.${network.matchConfig.MACAddress};
	nameFromNetdev =
	optional (
	(nameOrNull != null)
	&& flip any (attrValues config.systemd.network.netdevs) (x:
	(x ? netdevConfig.Name)
	&& (firstValue x.netdevConfig.Name) == nameOrNull)
	)
	nameOrNull;

The problem boils down to systemd allowing multiple values per statement, and also multiple statements for matchconfig attributes (within unit files). The code assumes a single string is set. This is undefined zone since there is no actual MatchConfig section verification done in the nixos options.
Just letting you know. I'll update my configs to use a single string value (no problem for my use cases)

EDIT; To complete the context; I assigned my MACAddress values as list of strings. The changes done to make the topology work in the current version is this;

Bert-Proesmans/nix@e683a9f#diff-f2581a441054e01442c6112782164ef45409e8fc0dc923090f6574ee057e9d63

[oddlama]

Oh good point, I guess I could disambiguate between single or multiple values here too. In theory we might want to be able to match interface configurations with multiple MacAddress statements