nixos/routnerr-2: enable wireguard_exporter

nixos/routnerr-2/configuration.nix

@@ -33,9 +33,18 @@ in {
     ./wgipamd.nix
 
     # Out-of-tree modules.
+    ./lib/modules/wireguard_exporter.nix
     ./lib/modules/wgipamd.nix
   ];
 
+  # Overlays for out-of-tree packages.
+  nixpkgs.overlays = [
+    (self: super: {
+      wireguard_exporter =
+        super.callPackage ./lib/pkgs/wireguard_exporter.nix { };
+    })
+  ];
+
   # Use the GRUB 2 boot loader with MBR.
   boot = {
     kernel = {
@@ -71,8 +80,9 @@ in {
     cbfstool
     flashrom
 
-    # Unstable packages.
+    # Unstable and out-of-tree packages.
     unstable.corerad
+    wireguard_exporter
   ];
 
   # Use server as a remote builder.

nixos/routnerr-2/networking.nix

@@ -106,4 +106,19 @@ in {
     nat.enable = false;
     firewall.enable = false;
   };
+
+  # Enable Prometheus exporter and set up peer key/name mappings.
+  # TODO: nixify the configuration.
+  services.wireguard_exporter = {
+    enable = true;
+    config = ''
+      [[peer]]
+      public_key = "VWRsPtbdGtcNyaQ+cFAZfZnYL05uj+XINQS6yQY5gQ8="
+      name = "mdlayher-fastly"
+
+      [[peer]]
+      public_key = "UvwWyMQ1ckLEG82Qdooyr0UzJhqOlzzcx90DXuwMTDA="
+      name = "nerr-3"
+    '';
+  };
 }