Use nix-snapshotter as k3s' snapshotter and image service

Replace k3s' embedded containerd with Nix-managed one
Deploy test k8s with image from Nix store

kubenix-modules/all.nix

@@ -24,6 +24,26 @@ let
   ];
 in
 {
+  kubernetes.resources.pods.testje.spec = {
+    containers.redis = {
+      image = "nix:0/nix/store/5nmh9qawhbwinzxidafjlfw68wfkh0pj-nix-image-redis.tar";
+      args = [ "--protected-mode" "no" ];
+
+      ports = [{
+        name = "redis";
+        containerPort = 6379;
+      }];
+    };
+
+    affinity.nodeAffinity.requiredDuringSchedulingIgnoredDuringExecution.nodeSelectorTerms = [{
+      matchExpressions = [{
+        key = "kubernetes.io/hostname";
+        operator = "In";
+        values = [ "atlas" ];
+      }];
+    }];
+  };
+
   imports = [
     ./base.nix
     ./longhorn.nix