nix-samples/helm-poc/nix/helm.nix

{
  pkgs ? import <nixpkgs> {}
, helm ? "${pkgs.kubernetes-helm}/bin/helm"
, lib ? pkgs.lib
}:
let
  mkHelm = {
    name,
    version,
    url,
    hash ? lib.fakeSha25,
    namespace ? "",
    patches ? []
  }:
    pkgs.stdenv.mkDerivation {
      inherit name patches;

      src = pkgs.fetchurl {
        inherit url hash;
      };

      phases = [
        "unpackPhase"
        "patchPhase"
        "build" 
      ];

      namespace = if namespace != "" then "--namespace ${namespace}" else "";

      build = ''
        mkdir -p $out
        ${helm} template \
          --namespace ${namespace} \
          ${name} ./ > $out/${name}-${version}.yaml
        ${helm} version > $out/VERSION
      '';
    };

  nixHelm = { 
    inherit mkHelm;
  };
in
  nixHelm