nixos/k3s: add test for airgap images import

Add a nixos test that imports the airgap images
archive and checks whether all expected images are
successfully loaded by k3s.

nixos/modules/services/cluster/k3s/default.nix

@@ -351,12 +351,16 @@ in
             sha256 = "0imblp0kw9vkcr7sp962jmj20fpmb3hvd3hmf4cs4x04klnq3k90";
             finalImageTag = "21.1.2-debian-11-r0";
           })
+
+          config.services.k3s.package.airgapImages
         ]
       '';
       description = ''
         List of derivations that provide container images.
         All images are linked to {file}`${imageDir}` before k3s starts and consequently imported
-        by the k3s agent. This option only makes sense on nodes with an enabled agent.
+        by the k3s agent. Consider importing the k3s airgap images archive of the k3s package in
+        use, if you want to pre-provision this node with all k3s container images. This option
+        only makes sense on nodes with an enabled agent.
       '';
     };
 

nixos/tests/k3s/airgap-images.nix

@@ -5,28 +5,26 @@ import ../make-test-python.nix (
     name = "${k3s.name}-airgap-images";
     meta.maintainers = lib.teams.k3s.members;
 
-    nodes.machine =
-      { pkgs, ... }:
-      {
-        # k3s uses enough resources the default vm fails.
-        virtualisation.memorySize = 1536;
-        virtualisation.diskSize = 4096;
+    nodes.machine = _: {
+      # k3s uses enough resources the default vm fails.
+      virtualisation.memorySize = 1536;
+      virtualisation.diskSize = 4096;
 
-        services.k3s = {
-          enable = true;
-          role = "server";
-          package = k3s;
-          # Slightly reduce resource usage
-          extraFlags = [
-            "--disable coredns"
-            "--disable local-storage"
-            "--disable metrics-server"
-            "--disable servicelb"
-            "--disable traefik"
-          ];
-          images = [ k3s.airgapImages ];
-        };
+      services.k3s = {
+        enable = true;
+        role = "server";
+        package = k3s;
+        # Slightly reduce resource usage
+        extraFlags = [
+          "--disable coredns"
+          "--disable local-storage"
+          "--disable metrics-server"
+          "--disable servicelb"
+          "--disable traefik"
+        ];
+        images = [ k3s.airgapImages ];
       };
+    };
 
     testScript = ''
       import json

nixos/tests/k3s/default.nix

@@ -7,6 +7,9 @@ let
   allK3s = lib.filterAttrs (n: _: lib.strings.hasPrefix "k3s_" n) pkgs;
 in
 {
+  airgap-images = lib.mapAttrs (
+    _: k3s: import ./airgap-images.nix { inherit system pkgs k3s; }
+  ) allK3s;
   auto-deploy = lib.mapAttrs (_: k3s: import ./auto-deploy.nix { inherit system pkgs k3s; }) allK3s;
   etcd = lib.mapAttrs (
     _: k3s: