Adding an extend example (helm+oci)

helm-poc/nix/helm.nix

@@ -10,9 +10,10 @@ let
     url,
     hash ? lib.fakeSha25,
     namespace ? "",
-    patches ? []
+    patches ? [],
+    values ? ""
   }:
-    pkgs.stdenv.mkDerivation {
+    pkgs.stdenv.mkDerivation rec {
       inherit name patches;
 
       src = pkgs.fetchurl {
@@ -25,12 +26,14 @@ let
         "build" 
       ];
 
-      namespace = if namespace != "" then "--namespace ${namespace}" else "";
+      namespaceOpts = if namespace != "" then "--namespace ${namespace}" else "";
+      valuesOpts = if values != "" then "--values ${values}" else "";
 
       build = ''
         mkdir -p $out
         ${helm} template \
-          --namespace ${namespace} \
+          ${namespaceOpts} \
+          ${valuesOpts} \
           ${name} ./ > $out/${name}-${version}.yaml
         ${helm} version > $out/VERSION
       '';