nixos/tests/incus: use runTestOn to limit systems, skip VMs aarch64-linux

nixos/tests/all-tests.nix

@@ -743,11 +743,11 @@ in
   immich-vectorchord-reindex = runTest ./web-apps/immich-vectorchord-reindex.nix;
   incron = runTest ./incron.nix;
   incus = import ./incus {
-    inherit runTest;
+    inherit runTestOn;
     package = pkgs.incus;
   };
   incus-lts = import ./incus {
-    inherit runTest;
+    inherit runTestOn;
     package = pkgs.incus-lts;
   };
   influxdb = runTest ./influxdb.nix;

nixos/tests/incus/default.nix

@@ -1,11 +1,11 @@
 {
   package,
-  runTest,
+  runTestOn,
 }:
 let
   incusRunTest =
     config:
-    runTest {
+    runTestOn [ "x86_64-linux" "aarch64-linux" ] {
       imports = [
         ./incus-tests-module.nix
         ./incus-tests.nix
@@ -18,6 +18,8 @@ let
     };
 in
 {
+  # this is the main test which will test as much as possible
+  # run this for testing incus upgrades, also available in incus package tests
   all = incusRunTest {
     name = "all";
     appArmor = true;
@@ -43,6 +45,7 @@ in
     };
   };
 
+  # used in lxc tests to verify container functionality
   container = incusRunTest {
     name = "container";
 
@@ -63,7 +66,7 @@ in
     network.ovs = true;
   };
 
-  ui = runTest {
+  ui = runTestOn [ "x86_64-linux" "aarch64-linux" ] {
     imports = [ ./ui.nix ];
 
     _module.args = { inherit package; };

nixos/tests/incus/incus-tests.nix

@@ -5,14 +5,29 @@
   ...
 }:
 
-# TODO aarch64 vm filter
 let
   cfg = config.tests.incus;
 
-  instanceScript = lib.foldlAttrs (
-    acc: name: instance:
-    acc + instance.testScript
-  ) "" cfg.instances;
+  # limit building of VMs to these systems as nested virtualization is
+  # required to test VMs, but support for this is poor outside x86
+  # will print warnings on those systems rather than failing outright
+  vmsEnabled = lib.elem pkgs.stdenv.system [ "x86_64-linux" ];
+
+  instanceScript = lib.pipe cfg.instances [
+    (lib.filterAttrs (
+      name: instance:
+      let
+        keep = instance.type != "virtual-machine" || vmsEnabled;
+      in
+      lib.warnIf (!keep) ''
+        Skipping virtual-machine ${name} as VMs are disabled on ${pkgs.stdenv.system}
+      '' keep
+    ))
+    (lib.foldlAttrs (
+      acc: name: instance:
+      acc + instance.testScript
+    ) "")
+  ];
 in
 {
   name = "${cfg.package.name}-${cfg.name}";
@@ -21,9 +36,6 @@ in
     maintainers = lib.teams.lxc.members;
   };
 
-  # sshBackdoor.enable = true;
-  # enableDebugHook = true;
-
   nodes.server = {
     virtualisation = {
       cores = 2;