Excellent GoRails Article(which is main source for this guide too). I did benefited from lot of other resources online as well.
Creating droplet on DigitalOcean(DO):
There are few options for this step, DO provide us some pre built images for lot of platforms in which they have pre-installed nginx, node and other related dependencies for each image. Rails one is little outdated, I tried that but didn't go very well for me, you can give it a shot if you have enough time.
For this guide we will go with bear bone ubuntu 18.04 server.
While creating the droplet, you will be asked to set an ssh key, just generate an ssh key with
ssh-keygen on your local system and copy contents of
.pub file into the textbox provided.
Select your resources and create droplet(provide your ssh key while creating and enable private networking, ipv6 and monitoring, this all is free).