nginx/files/_letsencrypt.conf

location /.well-known/acme-challenge/ {
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header Host $http_host;
    proxy_redirect off;
    proxy_pass http://{{ site.host.name }}:9999/.well-known/acme-challenge/;
}