abstract CLI image generation

and add busybox in all the images

kubernetes-helm/default.nix

@@ -1,20 +1,7 @@
-{ dockerTools
-, cacert
+{ buildCLIImage
 , kubernetes-helm
 }:
-dockerTools.buildLayeredImage {
-  inherit (kubernetes-helm) name;
-
-  contents = [
-    cacert
-    kubernetes-helm
-  ];
-
-  config = {
-    Entrypoint = [ "/bin/helm" ];
-    Env = [
-      "PATH=/bin"
-      "SSL_CERT_FILE=${cacert}/etc/ssl/certs/ca-bundle.crt"
-    ];
-  };
+buildCLIImage {
+  drv = kubernetes-helm;
+  binName = "helm";
 }