Replace remarshal with yq (#26)

Remarshal doesn’t seem to be maintained anymore.

It is also affected by upstream bugs like https://github.com/yaml/pyyaml/issues/89 which affects e.g. prometheus-operator CRDs.

lib/helm/chart2json.nix

@@ -1,10 +1,8 @@
 {
-  stdenvNoCC,
+  runCommand,
   lib,
   kubernetes-helm,
-  gawk,
-  remarshal,
-  jq,
+  yq,
 }:
 with lib;
   {
@@ -24,37 +22,25 @@ with lib;
     noHooks ? false,
   }: let
     valuesJsonFile = builtins.toFile "${name}-values.json" (builtins.toJSON values);
-  in
-    stdenvNoCC.mkDerivation {
-      name = "${name}.json";
-      buildCommand = ''
-        # template helm file and write resources to yaml
-        helm template "${name}" \
+    # The `helm template` and YAML -> JSON steps are separate `runCommand` derivations for easier debuggability
+    resourcesYaml = runCommand "${name}.yaml" {nativeBuildInputs = [kubernetes-helm];} ''
+      helm template "${name}" \
           ${optionalString (kubeVersion != null) "--kube-version ${kubeVersion}"} \
           ${optionalString (namespace != null) "--namespace ${namespace}"} \
           ${optionalString (values != {}) "-f ${valuesJsonFile}"} \
           ${optionalString includeCRDs "--include-crds"} \
           ${optionalString noHooks "--no-hooks"} \
-          ${chart} >resources.yaml
-
-        # split multy yaml file into multiple files
-        awk 'BEGIN{i=1}{line[i++]=$0}END{j=1;n=0; while (j<i) {if (line[j] ~ /^---/) n++; else print line[j] >>"resource-"n".yaml"; j++}}' resources.yaml
-
-        # join multiple yaml files in jsonl file
-        for file in ./resource-*.yaml
-        do
-          remarshal -i $file -if yaml -of json >>resources.jsonl
-        done
-
-        # convert jsonl file to json array, remove null values and write to $out
-        cat resources.jsonl | jq -Scs 'walk(
-          if type == "object" then
-            with_entries(select(.value != null))
-          elif type == "array" then
-            map(select(. != null))
-          else
-            .
-          end)' > $out
-      '';
-      nativeBuildInputs = [kubernetes-helm gawk remarshal jq];
-    }
+          ${chart} >$out
+    '';
+  in
+    runCommand "${name}.json" {} ''
+      # Remove null values
+      ${yq}/bin/yq -Scs 'walk(
+        if type == "object" then
+          with_entries(select(.value != null))
+        elif type == "array" then
+          map(select(. != null))
+        else
+          .
+        end)' ${resourcesYaml} >$out
+    ''