github.com/hashicorp/packer@v1.14.3/command/test-fixtures/hcl2_upgrade/varfile-with-no-variables-block/input.json (about)

     1  {
     2    "builders": [
     3      {
     4        "type": "null",
     5        "communicator": "ssh",
     6        "ssh_host": "{{ user `ssh_host` }}", 
     7        "ssh_password": "{{ user `ssh_password` }}",
     8        "ssh_username": "{{ user `ssh_username` }}"
     9      }
    10    ],
    11    "provisioners": [
    12      {
    13          "pause_before": "20s",
    14          "type": "shell-local",
    15          "inline": [ "echo {{ user `version_tag` }} > provision.txt" ]
    16      }
    17    ]
    18  }