zones: make zonefiles available as packages

krebs/3modules/zones.nix

@@ -1,22 +1,36 @@
 with import <stockholm/lib>;
-{ config, ... }: {
+{ config, pkgs, ... }: {
 
   config = {
-    # Implements environment.etc."zones/<zone-name>"
+    environment.etc =
-    environment.etc = let
+      mapAttrs'
+        (name: pkg: {
+          name = "zones/${name}";
+          value.source = pkg;
+        })
+        pkgs.krebs.zones;
+
+    nixpkgs.overlays = [
+      # Explicit zones generated from config.krebs.hosts.*.extraZones
+      (self: super: let
         stripEmptyLines = s: (concatStringsSep "\n"
           (remove "\n" (remove "" (splitString "\n" s)))) + "\n";
         all-zones = foldAttrs (sum: current: sum + "\n" + current) ""
           ([config.krebs.zone-head-config] ++ combined-hosts);
         combined-hosts =
           mapAttrsToList (name: getAttr "extraZones") config.krebs.hosts;
-    in
+      in {
+        krebs = super.krebs or {} // {
+          zones = super.krebs.zones or {} //
             mapAttrs'
               (name: value: {
-          name = "zones/${name}";
+                name = name;
-          value.text = stripEmptyLines value;
+                value = self.writeText "${name}.zone" (stripEmptyLines value);
               })
               all-zones;
         };
+      })
+    ];
+  };
 
 }