Variable Name for a file to used in the Packer configuration JSON.

For certain builds, like amazon-instance the x509_cert_path & x509_key_path are required. The given variable name can then be referenced in the configuration file as the value for a path.

Example JSON configuration:

    {
        "type": "amazon-instance",
        "x509_cert_path": "{{user `x509_cert`}}",
        ....etc...
    }
    

Then the Variable Name would be: x509_cert with the contents as the cert. Others such as x509_key_path can be specified in the same manor.

For more details consult Packer documentation.