This is the webserver component of the stack.
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 which is accessible from your host when using VirtualBox or Docker on Linux. A DNS entry makes app-vm.codeenigma.com and any subdomain point to it, meaning you can access it at whatever.app-vm.codeenigma.com directly.
When using Docker on Mac/Windows, it is only accessible through port forwarding, which means you need to add an host entry pointing to 127.0.0.1 to access it through a domain name.
It bundles together: