Serving different API versions through custom Api-Version header with Nginx

vhost.conf

server {
    listen 80;
    server_name api.domain.com;

    # Set default API version
    if ($http_api_version = '') {
        set $http_api_version 1;
    }

    # Forbid unsupported API versions
    if ($http_api_version ~ [^1-3]) {
        return 406;
    }

    root /home/root/api.domain.com/v$http_api_version/public;
    index index.php;
    charset utf-8;

    # Add headers to handle caching issues
    add_header "Api-Version" $http_api_version;
    add_header "Vary" "Api-Version";

    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/api.domain.com-error.log error;
    error_page 404 /index.php;

    location ~ \.php$ {
        fastcgi_split_path_info ^(.+\.php)(/.+)$;
        fastcgi_pass unix:/var/run/php/php7.0-fpm.sock;
        fastcgi_index index.php;
        include fastcgi.conf;
    }

    location ~ /\.ht {
        deny all;
    }
}