magnum/magnum/templates/docker-swarm/fragments/write-heat-params.yaml

#cloud-config
merge_how: dict(recurse_array)+list(append)
write_files:
  - path: /etc/sysconfig/heat-params
    owner: "root:root"
    permissions: "0644"
    content: |
      WAIT_HANDLE="$WAIT_HANDLE"