This is a little trick I use to spin up the packages instalation on **Debian/Ubuntu boxes** in **Vagrant**.

I add a simple function that checks if a directory named something similar to `~/.vagrant.d/cache/apt/opscode-ubuntu-12.04/partial` (it may have another path in Windows or MacOS) and create the directory if it doesn't already exist.

```ruby
def local_cache(basebox_name)
  cache_dir = Vagrant::Environment.new.home_path.join('cache', 'apt', basebox_name)
  partial_dir = cache_dir.join('partial')
  partial_dir.mkdir unless partial_dir.exist?
  cache_dir
end
```

I put this funcion in my `Vagrantfile` so I can use it like this:

```ruby
Vagrant::Config.run do |config|
  config.vm.box = "opscode-ubuntu-12.04"
  config.vm.box_url = "https://opscode-vm.s3.amazonaws.com/vagrant/boxes/opscode-ubuntu-12.04.box"
  cache_dir = local_cache(config.vm.box)

  config.vm.share_folder "v-cache",
                         "/var/cache/apt/archives/",
                         cache_dir

end
```

The result is that the *apt cache* inside the VM (`/var/cache/apt/archives/`) is always mounted on the same directory on the host (`~/.vagrant.d/cache/apt/opscode-ubuntu-12.04/` in this case) and *apt* just download the packages the first time or if the package has been updated.

This save me a lot of time while I'm developing or debuging Chef cookbooks. Mostly when my recipes need to install many packages.