Assign default interface

[codeapart]

How can I assign a default bridge interface? I added the following line to the Vagrant file:
config.vm.network "public_network", bridge: 'en2: Wi-Fi (AirPort)'

but when it boots up it still asks me for the interface to bridge to:

Bringing machine 'default' up with 'virtualbox' provider...
==> default: Checking if box 'rasmus/php7dev' is up to date...
==> default: Clearing any previously set forwarded ports...
==> default: Clearing any previously set network interfaces...
==> default: Available bridged network interfaces:

1. en2: Wi-Fi (AirPort)
2. en0: Ethernet 1
3. en1: Ethernet 2
4. p2p0
   ==> default: When choosing an interface, it is usually the one that is
   ==> default: being used to connect to the internet.
   default: Which interface should the network bridge to? 1
   ==> default: Preparing network interfaces based on configuration...
   default: Adapter 1: nat
   default: Adapter 2: hostonly
   default: Adapter 3: bridged
   default: Adapter 4: bridged
   ==> default: Forwarding ports...
   default: 80 (guest) => 8000 (host) (adapter 1)
   default: 443 (guest) => 44300 (host) (adapter 1)
   default: 3306 (guest) => 33060 (host) (adapter 1)
   default: 22 (guest) => 2222 (host) (adapter 1)
   ==> default: Running 'pre-boot' VM customizations...
   ==> default: Booting VM...
   ==> default: Waiting for machine to boot. This may take a few minutes...
   default: SSH address: 127.0.0.1:2222
   default: SSH username: vagrant
   default: SSH auth method: private key
   ==> default: Machine booted and ready!
   [default] GuestAdditions 5.0.26 running --- OK.
   ==> default: Checking for guest additions in VM...
   ==> default: Setting hostname...
   ==> default: Configuring and enabling network interfaces...
   ==> default: Mounting shared folders...
   default: /vagrant => /Volumes/Scratch/VMs/lca
   ==> default: Machine already provisioned. Run vagrant provision or use the --provision
   ==> default: flag to force provisioning. Provisioners marked to run always will still run.