helm-vdiff: A shell script to compare Helm chart values across versions, whether remote, OCI, or installed releases

helm-vdiff

helm-vdiff() {
  local namespace="default" values="" value_key=""
  local diff_cmd=(dyff between --omit-header)
  local positional=()

  # argument parsing
  while [[ $# -gt 0 ]]; do
    case "$1" in
      -n|--namespace) namespace="$2"; shift 2;;
      -v|--values) values="$2"; shift 2;;
      -k|--value-key) value_key="$2"; shift 2;;
      -i|--icdiff) diff_cmd=(icdiff --highlight -U5); shift;;
      -*) echo "Unknown option: $1"; return 1;;
      *) positional+=("$1"); shift;;
    esac
  done

  # restore positional parameters
  set -- "${positional[@]}"

  local left="$1"
  local right="$2"

  if [[ -z "$left" || -z "$right" ]]; then
    echo "Usage:"
    echo "  helm-vdiff [options] <source> <target>"
    echo
    echo "Remote vs Remote:"
    echo "  helm-vdiff cnpg/cloudnative-pg:0.18.0 cnpg/cloudnative-pg:0.18.1"
    echo "  helm-vdiff cnpg/cloudnative-pg:0.18.0 oci://registry-1.docker.io/bitnamicharts/postgresql:18.0.9"
    echo
    echo "OCI vs OCI:"
    echo "  helm-vdiff oci://quay.io/cilium/charts/cilium:1.19.0 oci://quay.io/cilium/charts/cilium:1.19.1"
    echo
    echo "Repo vs OCI:"
    echo "  helm-vdiff cilium/cilium:1.19.0 oci://quay.io/cilium/charts/cilium:1.19.1"
    echo
    echo "Installed Release vs Remote:"
    echo "  helm-vdiff -n kube-system kube-system-cilium oci://quay.io/cilium/charts/cilium:1.18.6"
    echo
    echo "With extra values:"
    echo "  helm-vdiff cnpg/cloudnative-pg:0.23.1 cnpg/cloudnative-pg:0.23.2 -v values.yaml"
    echo
    echo "With values subkey:"
    echo "  helm-vdiff cnpg/cloudnative-pg:0.23.1 cnpg/cloudnative-pg:0.23.2 -v values.yaml -k cloudnative-pg"
    echo
    echo "Useful:"
    echo "  oras repo tags quay.io/cilium/charts/cilium"
    echo "  helm repo add cilium https://helm.cilium.io/"
    echo "  helm search repo cilium --versions"
    echo
    echo "Options:"
    echo "  -n, --namespace    Namespace for installed release"
    echo "  -v, --values       Extra values.yaml"
    echo "  -k, --value-key    Only compare subkey of values"
    echo "  -i, --icdiff       Use icdiff instead of dyff"
    return 1
  fi

  get_values() {
    local ref="$1"

    # OCI or repo/chart:version
    if [[ "$ref" == oci://* || "$ref" == */*:* ]]; then
      local chart="${ref%:*}"
      local version="${ref##*:}"
      helm show values "$chart" --version "$version" 2> /dev/null | yq --prettyPrint eval '... comments="" | sortKeys(..)' | sed 's/: ~$/: null/'

    # repo/chart (no version)
    elif [[ "$ref" == */* ]]; then
      helm show values "$ref" 2> /dev/null | yq --prettyPrint eval '... comments="" | sortKeys(..)' | sed 's/: ~$/: null/'

    # assume installed release
    else
      helm get values --all "$ref" -n "$namespace" | tail -n +2
    fi
  }

  left_values=$(get_values "$left")
  right_values=$(get_values "$right")

  # merge extra values (only into left side)
  if [[ -n "$values" ]]; then
    if [[ -n "$value_key" ]]; then
      left_values=$(yq eval-all \
        "select(fileIndex == 0) * select(fileIndex == 1)" \
        <(echo "$left_values") \
        <(yq eval ".${value_key}" "$values"))
    else
      left_values=$(yq eval-all \
        "select(fileIndex == 0) * select(fileIndex == 1)" \
        <(echo "$left_values") \
        "$values")
    fi
  fi

  "${diff_cmd[@]}" \
    <(echo "$left_values" | yq eval 'sortKeys(..)' -) \
    <(echo "$right_values" | yq eval 'sortKeys(..)' -)
}