start set up for multi-location nixos flake

nixos/hosts/olympus/dhcp/configuration.nix

@@ -0,0 +1,53 @@
+{ config, pkgs, hosts, ... }:
+let
+  hostToDhcp = { hostname, mac, ip, ... }: {
+    ethernetAddress = mac;
+    hostName = hostname;
+    ipAddress = ip;
+  };
+  hosts' = hosts.olympus;
+in {
+  imports = [ ];
+
+  networking = {
+    hostName = "dhcp";
+    defaultGateway = "10.42.42.1";
+    nameservers = [ "10.42.42.15" "10.42.42.16" ];
+    interfaces.eth0 = {
+      useDHCP = false; # It turns out the barber just doesn't shave
+      ipv4.addresses = [{
+        address = "10.42.42.3";
+        prefixLength = 23;
+      }];
+    };
+  };
+
+  # This value determines the NixOS release from which the default
+  # settings for stateful data, like file locations and database versions
+  # on your system were taken. It‘s perfectly fine and recommended to leave
+  # this value at the release version of the first install of this system.
+  # Before changing this value read the documentation for this option
+  # (e.g. man configuration.nix or on https://nixos.org/nixos/options.html).
+  system.stateVersion = "21.11"; # Did you read the comment?
+
+  # Additional packages
+  environment.systemPackages = with pkgs; [ ];
+
+  networking.firewall.allowedUDPPorts = [ 67 ];
+
+  services.dhcpd4 = {
+    enable = true;
+    extraConfig = ''
+      option subnet-mask 255.255.254.0;
+      option broadcast-address 10.42.43.255;
+      option routers 10.42.42.1;
+      option domain-name-servers 10.42.42.15, 10.42.42.16;
+      option domain-name "olympus";
+      option domain-search "olympus";
+      subnet 10.42.42.0 netmask 255.255.254.0 {
+        range 10.42.43.1 10.42.43.254;
+      }
+    '';
+    machines = map hostToDhcp hosts';
+  };
+}