{
  builders,
  pkgs,
}: rec {
  mkImageAttrs = image:
    with builtins; let
      vals = pkgs.lib.strings.splitString ":" image;

      # Tag may contain ":", such as `rolling@sha256:...`. Or it may not.
      # This contortion deals with both scenarios using `sublist`.
      tag = with builtins;
        concatStringsSep ":"
        (filter (x: typeOf x != "list")
          (pkgs.lib.lists.sublist 1 2 vals));
    in {
      repository = elemAt vals 0;
      inherit tag;
    };

  mkExistingClaim = {
    mountPath,
    pvc,
    subPath,
    readOnly ? true,
  }: {
    enabled = true;
    existingClaim = pvc;
    advancedMounts.main.main = [
      {
        path = mountPath;
        inherit readOnly subPath;
      }
    ];
  };

  build = {
    namespace,
    name,
    mainImage,
    chart,
    values ? {},
    kubeVersion ? pkgs.kubernetes.version,
    apiVersions ? [],
    extraOpts ? [],
  }:
    builders.helmChart {
      inherit name namespace chart kubeVersion apiVersions extraOpts;
      values =
        pkgs.lib.attrsets.recursiveUpdate
        {
          controllers.main.containers.main.image =
            mkImageAttrs mainImage;
        }
        values;
    };
}