How to setup server blocks with docker containers?

I am using Digital Ocean droplet. Here is a tutorial about how to setup server blocks: https://www.digitalocean.com/community/tutorials/how-to-set-up-nginx-server-blocks-virtual-hosts-on-ubuntu-14-04-lts

But my multiple websites are hosted in each docker container respectively. I need Nginx, or any other software, to do something like a router, i.e. forwarding different domain's service to different internal network address. In my case, the internal network consists of docker containers I deployed in that server with public IP.