feat(topology): add warning when connecting different networks

topology/options/interfaces.nix

@@ -11,6 +11,7 @@ f: {
     mkDefault
     mkIf
     mkOption
+    optional
     types
     ;
 in
@@ -124,5 +125,19 @@ in
               )
           )
       ));
+
+      warnings = flatten (flip map (attrValues config.nodes) (
+        node:
+          flip map (attrValues node.interfaces) (
+            interface:
+              flip map interface.physicalConnections (
+                physicalConnection: let
+                  otherNetwork = config.nodes.${physicalConnection.node}.interfaces.${physicalConnection.interface}.network or null;
+                in
+                  optional (interface.network != null && otherNetwork != null && interface.network != otherNetwork)
+                  "topology: The interface nodes.${node.id}.interfaces.${interface.id} is associated with the network (${interface.network}), but also has a physicalConnection to nodes.${physicalConnection.node}.interfaces.${physicalConnection.interface} which is associated to a different network (${otherNetwork})"
+              )
+          )
+      ));
     };
   }

topology/topology/default.nix

@@ -6,6 +6,7 @@
   inherit
     (lib)
     attrNames
+    concatLines
     concatLists
     concatStringsSep
     filter
@@ -19,6 +20,7 @@
     mkMerge
     mkOption
     types
+    warnIf
     ;
 
   availableRenderers = attrNames (filterAttrs (_: v: v == "directory") (builtins.readDir ./renderers));
@@ -94,6 +96,17 @@ in {
       });
     };
 
+    warnings = mkOption {
+      internal = true;
+      default = [];
+      example = ["This is deprecated for that reason"];
+      description = lib.mdDoc ''
+        This option allows modules to show warnings to users during
+        the evaluation of the topology configuration.
+      '';
+      type = types.listOf types.str;
+    };
+
     topology.isMainModule = mkOption {
       description = "Whether this is the toplevel topology module.";
       readOnly = true;
@@ -120,7 +133,10 @@ in {
     in
       if failedAssertions != []
       then throw "\nFailed assertions:\n${concatStringsSep "\n" (map (x: "- ${x}") failedAssertions)}"
-      else mkIf (config.renderer != null) (mkDefault config.renderers.${config.renderer}.output);
+      else
+        warnIf (config.warnings != [])
+        (concatLines (["The following warnings were raised during evaluation:"] ++ config.warnings))
+        (mkIf (config.renderer != null) (mkDefault config.renderers.${config.renderer}.output));
 
     nodes = aggregate ["nodes"];
     networks = aggregate ["networks"];

topology/topology/renderers/elk/default.nix

@@ -66,7 +66,7 @@
 
   mkLabel = text: scale: extraStyle: {
     height = scale * 12;
-    width = scale * 7.3 * (stringLength text);
+    width = scale * 7.2 * (stringLength text);
     inherit text;
     style =
       {