We have an article on bottle here: https://www.digitalocean.com/community/tutorials/how-to-use-the-bottle-micro-framework-to-develop-python-web-apps

anyone can help to serve an application bottle, with nginx or otherwise

Building off the article that Etel linked to, a "Hello World" Bottle app might look like:

from bottle import route, run

@route('/hello')
def hello():
    return "Hello World!"

run(host='0.0.0.0', port=3000)

You can set the port to anything you want. Now we can use Nginx as a reverse proxy. You Nginx configuration would look something like:

upstream app_server {
    server 127.0.0.1:3000 fail_timeout=0;
}

server {
    listen 80 default_server;
    listen [::]:80 default_server ipv6only=on;

    root /usr/share/nginx/html;
    index index.html index.htm;

    client_max_body_size 4G;
    server_name your-domain.com;

    keepalive_timeout 5;

    location / {
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_redirect off;
        proxy_pass http://app_server;
    }
}

Note that the upstream directive is on the same port as the Bottle app. To get Nginx installed in the first place, check out: https://www.digitalocean.com/community/tutorials/how-to-install-nginx-on-ubuntu-14-04-lts