As with every Vagrant provider, the Vagrant VMware providers have a custom box format.

This page documents the format so that you can create your own base boxes. Note that currently you must make these base boxes by hand. A future release of Vagrant will provide additional mechanisms for automatically creating such images.

Note: This is a reasonably advanced topic that a beginning user of Vagrant does not need to understand. If you are just getting started with Vagrant, skip this and use an available box. If you are an experienced user of Vagrant and want to create your own custom boxes, this is for you.

Prior to reading this page, please understand the basics of the box file format.


A VMware base box is a compressed archive of the necessary contents of a VMware "vmwarevm" file. Here is an example of what is contained in such a box:

$ tree
|-- disk-s001.vmdk
|-- disk-s002.vmdk
|-- ...
|-- disk.vmdk
|-- metadata.json
|-- precise64.nvram
|-- precise64.vmsd
|-- precise64.vmx
|-- precise64.vmxf

0 directories, 17 files

The files that are strictly required for a VMware machine to function are: nvram, vmsd, vmx, vmxf, and vmdk files.

There is also the "metadata.json" file used by Vagrant itself. This file contains nothing but the defaults which are documented on the box format page.

When bringing up a VMware backed machine, Vagrant copies all of the contents in the box into a privately managed "vmwarevm" folder, and uses the first "vmx" file found to control the machine.

Vagrant 1.8 and higher support linked clones. Prior versions of Vagrant do not support linked clones. For more information on linked clones, please see the documentation.

VMX Whitelisting

Settings in the VMX file control the behavior of the VMware virtual machine when it is booted. In the past Vagrant has removed the configured network device when creating a new instance and inserted a new configuration. With the introduction of "predictable network interface names" this approach can cause unexpected behaviors or errors with VMware Vagrant boxes. While some boxes that use the predictable network interface names are configured to handle the VMX modifications Vagrant makes, it is better if Vagrant does not make the modification at all.

Vagrant will now warn if a whitelisted setting is detected within a Vagrant box VMX file. If it is detected, a warning will be shown alerting the user and providing a configuration snippet. The configuration snippet can be used in the Vagrantfile if Vagrant fails to start the virtual machine.

Making compatible boxes

These are the VMX settings the whitelisting applies to:

If the newly created box does not depend on Vagrant's existing behavior of modifying this setting, it can disable Vagrant from applying the modification by adding a Vagrantfile to the box with the following content:

Vagrant.configure("2") do |config|
  ["vmware_workstation", "vmware_fusion"].each do |vmware_provider|
    config.vm.provider(vmware_provider) do |vmware|
      vmware.whitelist_verified = true

This will prevent Vagrant from displaying a warning to the user as well as disable the VMX settings modifications.

Installed Software

Base boxes for VMware should have the following software installed, as a bare minimum:

  • SSH server with key-based authentication setup. If you want the box to work with default Vagrant settings, the SSH user must be set to accept the insecure keypair that ships with Vagrant.

  • VMware Tools so that things such as shared folders can function. There are many other benefits to installing the tools, such as improved networking performance.

Optimizing Box Size

Prior to packaging up a box, you should shrink the hard drives as much as possible. This can be done with vmware-vdiskmanager which is usually found in /Applications/VMware Fusion.app/Contents/Library for VMware Fusion. You first want to defragment then shrink the drive. Usage shown below:

$ vmware-vdiskmanager -d /path/to/main.vmdk
$ vmware-vdiskmanager -k /path/to/main.vmdk


Remove any extraneous files from the "vmwarevm" folder and package it. Be sure to compress the tar with gzip (done below in a single command) since VMware hard disks are not compressed by default.

$ cd /path/to/my/vm.vmwarevm
$ tar cvzf custom.box ./*

© 2010–2017 Mitchell Hashimoto
Licensed under the MPL 2.0 License.