package common import ( "github.com/hashicorp/packer/template/interpolate" ) type VBoxVersionConfig struct { VBoxVersionFile *string `mapstructure:"virtualbox_version_file"` } func (c *VBoxVersionConfig) Prepare(ctx *interpolate.Context) []error { if c.VBoxVersionFile == nil { default_file := ".vbox_version" c.VBoxVersionFile = &default_file } return nil }