infra: steal from the best

(Mic92's cluster TUM's infra.)

modules/hosts.nix

@@ -0,0 +1,47 @@
+{ lib, config, ... }:
+let
+  hostOptions = with lib; {
+    ipv4 = mkOption {
+      default = null;
+      type = types.nullOr types.str;
+      description = ''
+        own ipv4 address
+      '';
+    };
+
+    ipv6 = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+      description = ''
+        own ipv6 address
+      '';
+    };
+  };
+in
+{
+  options = with lib; {
+    networking.newtype.hosts = mkOption {
+      type = with types; attrsOf (submodule [{ options = hostOptions; }]);
+      description = "A host in our cluster";
+    };
+    networking.newtype.currentHost = mkOption {
+      type = with types; submodule [{ options = hostOptions; }];
+      default = config.networking.newtype.hosts.${config.networking.hostName};
+      description = "The host that is described by this configuration";
+    };
+  };
+  config = {
+    warnings =
+      lib.optional (!(config.networking.newtype.hosts ? ${config.networking.hostName}) && 
+        config.networking.hostName != "nixos" # we dont care about nixos netboot/installer images
+      )
+        "Please add network configuration for ${config.networking.hostName}. None found in ${./hosts.nix}";
+
+    # usually, for each host there is a hostname.dse.in.tum.de and hostname.r domain
+    networking.newtype.hosts = {
+      epyc = {
+        ipv6 = "2001:470:ca5e:dee:587c:7a50:f36c:cae8";
+      };
+    };
+  };
+}