if [[ ! -f "${CLUSTER_TOPOLOGY_CONFIG_FILE}" ]]; then
    log 'cluster topology configuration file is not specified'
    exit 1
  fi

  export CLUSTER_NAMES
  export CLUSTER_POD_SUBNETS
  export CLUSTER_SVC_SUBNETS
  export CLUSTER_NETWORK_ID

  KUBE_CLUSTERS=$(jq '.[] | select(.kind == "Kubernetes" or .kind == null)' "${CLUSTER_TOPOLOGY_CONFIG_FILE}")

  while read -r value; do

  # ! does a variable-variable https://stackoverflow.com/a/10757531/374797
  for var in "${VARS[@]}"; do
    echo "${var}"="${!var}"
  done
else
  for var in "${VARS[@]}"; do
    # shellcheck disable=SC2163
    export "${var}"
  done

if [[ "${ISTIO_ZTUNNEL_BASE_URL}" != "https://storage.googleapis.com/istio-build/ztunnel" ]]; then
  AUTH_HEADER="Authorization: Bearer $(gcloud auth print-access-token)"
  export AUTH_HEADER
fi

ZTUNNEL_REPO_SHA="${ZTUNNEL_REPO_SHA:-$(grep ZTUNNEL_REPO_SHA istio.deps  -A 4 | grep lastStableSHA | cut -f 4 -d '"')}"
ISTIO_ZTUNNEL_VERSION="${ISTIO_ZTUNNEL_VERSION:-${ZTUNNEL_REPO_SHA}}"