How to setup mass dynamic virtual hosts in nginx?

Based on user2001260's answer, later edited by partlov, here's my outcome.

Bear in mind this is for a dev server located on a local virtual machine, where the .dev prefix is used at the end of each domain. If you want to remove it, or use something else, the \.dev part in the server_name directive could be edited or altogether removed.

server {
    listen 80 default_server;
    listen [::]:80 default_server;

    # Match any server name with the format [subdomain.[.subdomain...]].domain.tld.dev
    server_name ~^(?<subdomain>([\w-]+\.)*)?(?<domain>[\w-]+\.[\w-]+)\.dev$;

    # Map by default to (projects_root_path)/(domain.tld)/www;
    set $rootdir "/var/www/$domain/www";

    # Check if a (projects_root_path)/(subdomain.)(domain.tld)/www directory exists
    if (-f "/var/www/$subdomain.$domain/www"){
        # in which case, set that directory as the root
        set $rootdir "/var/www/$subdomain.$domain/www";
    } 

    root $rootdir;

    index index.php index.html index.htm index.nginx-debian.html;

    # Front-controller pattern as recommended by the nginx docs
    location / {
        try_files $uri $uri/ /index.php;
    }

    # Standard php-fpm based on the default config below this point
    location ~ \.php$ {
        include snippets/fastcgi-php.conf;
        fastcgi_pass unix:/run/php/php7.0-fpm.sock;
    }

    location ~ /\.ht {
        deny all;
    }

}

The regex in server_name captures the variables subdomain and domain. The subdomain part is optional and can be empty. I have set it so that by default, if you have a subdomain, say admin.mysite.com the root is set to the same root as mysite.com. This way, the same front-controller (in my case index.php) can route based on the subdomain. But if you want to keep an altogether different application in a subdomain, you can have a admin.mysite.com dir and it will use that directory for calls to admin.mysite.com.

Careful: The use of if is discouraged in the current nginx version, since it adds extra processing overhead for each request, but it should be fine for use in a dev environment, which is what this configuration is good for. In a production environment, I would recommend not using a mass virtual host configuration and configuring each site separately, for more control and better security.

server_name ~^(?<vhost>[^.]*)\.domain\.com$;
set $rootdir "/var/www/whatever/$vhost";
root $rootdir;

You will need some scripting knowledge to put this together. I would use PHP, but if you are good in bash scripting use that. I would do it like this:

1. First create some folder (/usr/local/etc/nginx/domain.com/).

2. In main nginx.conf add command : include /usr/local/etc/nginx/domain.com/*.conf;

3. Every file in this folder should be different vhost names subdomain.conf.

You do not need to restart nginx server for config to take action, you only need to reload it : /usr/local/etc/rc.d/nginx reload

OR you can make only one conf file, where all vhosts should be set. This is probably better so that nginx doesn't need to load up 50 files, but only one....

IF you have problems with scripting, then ask question about that...

Perhaps doing this will get you where you want to be:

server {

    root /sites/$http_host;

    server_name $http_host;

    ...

}

I like this as I can literally create sites on the fly, just create new directory named after the domain and point the DNS to the server ip.