Using VDD with Drupal 6 site I'm trying to get a Drupal 6 site up and running with the Vagrant Drupal Development project. 

I can get VDD going.. get my site installed, the database imported etc.. but I need to make VDD use an old version of PHP. I see some instructions online that say you can set which PHP version to use, but it isn't happening.. it doesn't say where in the json the setting needs to appear.

I tried with the following json, but it ended up as PHP Version 5.4.39-1+deb.sury.org~precise+2 :

{
  "php": {
    "version": "5.2.17"
  },
  "vm": {
    "ip": "192.168.44.44",
    "memory": "1024",
    "synced_folders": [
      {
        "host_path": "data/",
        "guest_path": "/var/www",
        "type": "default"
      }
    ],
    "forwarded_ports": []
  },
  "vdd": {
    "sites": {
      "drupal6site": {
        "account_name": "root",
        "account_pass": "root",
        "account_mail": "box@example.com",
        "site_name": "drupal6site",
        "site_mail": "box@example.com",
        "vhost": {
          "document_root": "drupal6site",
          "url": "drupal6site.dev",
          "alias": ["www.drupal6site.dev"]
        }
      }
    }
  }
}
VDD of  8 version doesn't support the feature of changing PHP version. You may try other Vagrant box for Drupal. For example this one, it has very good documentation.