This is the main component of the stack, combining the php cli, the webserver, etc.
You can interact with it in vagrant commands by targeting it as "app-vm". Eg:
vagrant up app-vm
vagrant ssh app-vm
This is also the "primary" vagrant VM, which means commands that apply to a single VM will default to app-vm. See vagrantup.com for more details on how vagrant interacts with multi machines.
It gets assigned the IP 192.168.56.2 and a DNS entry makes *.app-vm.codeenigma.com and point to it. You can access it at whatever.app-vm.codeenigma.com directly.
It bundles together: