Add option for Helm --include-crds (#18)

lib/helm/chart2json.nix

@@ -18,6 +18,8 @@ with lib;
     values ? {},
     # kubernetes version to template chart for
     kubeVersion ? null,
+    # whether to include CRD
+    includeCRDs ? false
   }: let
     valuesJsonFile = builtins.toFile "${name}-values.json" (builtins.toJSON values);
   in
@@ -29,6 +31,7 @@ with lib;
           ${optionalString (kubeVersion != null) "--kube-version ${kubeVersion}"} \
           ${optionalString (namespace != null) "--namespace ${namespace}"} \
           ${optionalString (values != {}) "-f ${valuesJsonFile}"} \
+          ${optionalString (includeCRDs) "--include-crds"} \
           ${chart} >resources.yaml
 
         # split multy yaml file into multiple files

modules/helm.nix

@@ -81,6 +81,20 @@ in {
             default = true;
           };
 
+          includeCRDs = mkOption {
+            description = '' 
+              Whether to include CRDs.
+
+              Warning: Always including CRDs here is dangerous and can break CRs in your cluster as CRDs may be updated unintentionally.
+              An interactive `helm install` NEVER updates CRDs, only installs them when they are not existing.
+              See https://github.com/helm/community/blob/aa8e13054d91ee69857b13149a9652be09133a61/hips/hip-0011.md
+            
+              Only set this to true if you know what you are doing and are manually checking the included CRDs for breaking changes whenever updating the Helm chart.
+            '';
+            type = types.bool;
+            default = false;
+          };
+
           objects = mkOption {
             description = "Generated kubernetes objects";
             type = types.listOf types.attrs;
@@ -95,7 +109,7 @@ in {
         ];
 
         config.objects = importJSON (helm.chart2json {
-          inherit (config) chart name namespace values kubeVersion;
+          inherit (config) chart name namespace values kubeVersion includeCRDs;
         });
       }));
       default = {};