Implement a generic helm templater package.

nix/kubernetes/keys/package/helm-manifest/package.nix

@@ -0,0 +1,48 @@
+# unpackPhase
+# patchPhase
+# configurePhase
+# buildPhase
+# checkPhase
+# installPhase
+# fixupPhase
+# installCheckPhase
+# distPhase
+{
+  lib,
+  pkgs,
+  stdenv,
+  kubernetes-helm,
+  helm_src,
+  helm_name,
+  helm_namespace,
+  helm_path ? ".",
+  helm_manifest_name,
+  helm_values ? { },
+  ...
+}:
+stdenv.mkDerivation (
+  finalAttrs:
+  let
+    to_yaml_file = ((import ../../../functions/to_yaml.nix) { inherit pkgs; }).to_yaml_file;
+  in
+  {
+    name = "${helm_name}-manifest";
+    nativeBuildInputs = [
+      kubernetes-helm
+    ];
+    buildInputs = [ ];
+
+    src = helm_src;
+
+    buildPhase = ''
+      helm template --dry-run=client ${lib.strings.escapeShellArg helm_name} $src/${helm_path} --namespace ${helm_namespace} \
+           --values ${to_yaml_file "values.yaml" helm_values} \
+           | tee $NIX_BUILD_TOP/${helm_manifest_name}
+    '';
+
+    installPhase = ''
+      mkdir -p "$out"
+      cp $NIX_BUILD_TOP/${helm_manifest_name} $out/
+    '';
+  }
+)