Add experimental nix-snapshotter stuff

nixos-modules/k3s/default.nix

@@ -1,4 +1,4 @@
-{ inputs, pkgs, lib, config, ... }:
+{ self, inputs, pkgs, lib, config, ... }:
 let
   cfg = config.lab.k3s;
 
@@ -167,9 +167,30 @@ in
           cp -f ${./k3s-ca/etcd/server-ca.crt} /var/lib/rancher/k3s/server/tls/etcd/server-ca.crt
         '';
 
-        nix-snapshotter-image = ''
-          ln -sf ${image} /root/image.tar
-        '';
+        docker-images =
+          let
+            pulledImages = (import "${self}/container-images/pulled-images.nix") pkgs lib;
+            basePath = "/var/docker_images";
+            linesForImage = projectName: imageName: pulledImage:
+              let
+                projectPath = "${basePath}/${projectName}";
+              in
+              ''
+                mkdir -p ${projectPath}
+                ln -sf ${pulledImage} ${projectPath}/${imageName}.tar
+              '';
+            linesForProject = projectName: project:
+              let
+                lines = lib.attrsets.mapAttrsToList (linesForImage projectName) project;
+              in
+              builtins.concatStringsSep "\n" lines;
+            generateLines = projects:
+              let
+                lines = lib.attrsets.mapAttrsToList linesForProject projects;
+              in
+              builtins.concatStringsSep "\n" lines;
+          in
+          generateLines pulledImages;
       };
     };