For use with Laravel Homestead. Set a server_name to add for ngrok (or similar services, but my useccase is ngrok.) With this type of setup, I can use Homestead globally (only one vm for many sites) and add an additional domain for ngrok on the sites I wish to load it with.

Homestead.yaml

---
ip: "10.10.192.168"
memory: 2048
cpus: 1
provider: virtualbox
name: homestead-7

authorize: ~/.ssh/id_rsa.pub

keys:
    - ~/.ssh/id_rsa

folders:
    - map: ~/www
      to: /home/vagrant/Code

sites:
    - map: mydev.test
      to: /home/vagrant/Code/test/public
      type: ngrokEnabled
      params: 
        - key: ngrokName
          value: {WHATEVER_YOU_WANT_TO_USE}.ngrok.io
databases:
    - Homestead

# blackfire:
#     - id: foo
#       token: bar
#       client-id: foo
#       client-token: bar

# ports:
#     - send: 50000
#       to: 5000
#     - send: 7777
#       to: 777
#       protocol: udp

serve-ngrokEnabled.sh

#!/usr/bin/env bash

###
# Homestead/scripts/serve-ngrokEnabled.sh
###
# This is a copy, basically, of the serve-laravel.sh script, 
# but modded to look for my custom param (ngrokName) and
# add it to server_name if it exists. This will only 
# execute on sites that are of type: ngrokEnabled
###
# The ngrok command I use to run share these sites is as follows:
# ngrok http mydev.test:80 --subdomain={WHATEVER_YOU_WANT_TO_USE}
###

declare -A params=$6     # Create an associative array
paramsTXT=""
if [ -n "$6" ]; then
   for element in "${!params[@]}"
   do
      paramsTXT="${paramsTXT}
        fastcgi_param ${element} ${params[$element]};"
   done
fi

if test "${params['ngrokName']+isset}"
    then
        echo "${params[ngrokName]} will be added to \"$1\" server name"
    else
        params['ngrokName']=""
fi

block="server {
    listen ${3:-80};
    listen ${4:-443} ssl http2;
    server_name $1 ${params[ngrokName]};
    root \"$2\";

    index index.html index.htm index.php;

    charset utf-8;

    location / {
        try_files \$uri \$uri/ /index.php?\$query_string;
    }

    location = /favicon.ico { access_log off; log_not_found off; }
    location = /robots.txt  { access_log off; log_not_found off; }

    access_log off;
    error_log  /var/log/nginx/$1-error.log error;

    sendfile off;

    client_max_body_size 100m;

    location ~ \.php$ {
        fastcgi_split_path_info ^(.+\.php)(/.+)$;
        fastcgi_pass unix:/var/run/php/php$5-fpm.sock;
        fastcgi_index index.php;
        include fastcgi_params;
        fastcgi_param SCRIPT_FILENAME \$document_root\$fastcgi_script_name;
        $paramsTXT

        fastcgi_intercept_errors off;
        fastcgi_buffer_size 16k;
        fastcgi_buffers 4 16k;
        fastcgi_connect_timeout 300;
        fastcgi_send_timeout 300;
        fastcgi_read_timeout 300;
    }

    location ~ /\.ht {
        deny all;
    }

    ssl_certificate     /etc/nginx/ssl/$1.crt;
    ssl_certificate_key /etc/nginx/ssl/$1.key;
}
"

echo "$block" > "/etc/nginx/sites-available/$1"
ln -fs "/etc/nginx/sites-available/$1" "/etc/nginx/sites-enabled/$1"