How do you write a drush alias for a local Vagrant box?
I was able to use drush alias with following configuration:

Let's assume two things:


vagrant box has some sort of static ip (can be private, for example: 192.168.56.101)
IP of vagrant is available in symbolic form (for example, we have single line in /etc/hosts with ip and hostname). (for example: test.site.local).


Step 1:
We need to copy settings, generated by vagrant ssh-config command into $HOME/.ssh/config

Host test.site.local
    IdentitiesOnly yes
    UserKnownHostsFile /dev/null
    StrictHostKeyChecking no
    PasswordAuthentication no
    IdentityFile [path to vagrant private insecure key]


Step 2:
With such configuration, my alias was in following form:

$aliases['example'] = array(
   'root' =&gt; '/var/www',
   'uri' =&gt; 'test.site.local',
   'remote-host' =&gt; 'test.site.local',
   'remote-user' =&gt; 'vagrant',
   'ssh-options' =&gt; "-i path_to_insecure_private_key"
);