Oracle VM VirtualBox (formerly Sun VirtualBox, Sun xVM VirtualBox and innotek VirtualBox) is a virtualization software package for x86 and AMD64/Intel64-based computers from Oracle Corporation as part of its family of virtualization products

Since VirtualBox-4.3.8-4 PLD package, you can autostart guests:

1. edit /etc/vbox/autostart.cfg and fill which users may access the feature
2. as user, configure autostart dbpath:

   $ VBoxManage setproperty autostartdbpath /etc/vbox/autostart

3. modify VM to enable autostart of it:

   $ VBoxManage modifyvm <uuid|vmname> --autostart-enabled on

You can use VBoxManage list vms or VBoxManage list runningvms to figure out the UUID or VM name).

If you're using vagrant, then you can obtain uuid from id file:

$ cat .vagrant/machines/default/virtualbox/id
238dd504-f9f5-48c9-b214-cf64f16dc0ce

NB! VM needs to be stopped for modifyvm command to succeed.

Starting with version 4.0, VirtualBox can mount shared folders automatically. However it needed hardcoded group vboxsf to exist, no errors were shown if the group did not exist.

The group was added in VirtualBox-guest-4.3.8-4 package.

However, the automounter is still very poor, it will stop mounting other shared folders if there's problem with one of them (shared source folder missing, permission error etc). To debug this, run VBoxService -v -v -v in verbose mode in guest.