I think it can be simple if you keep it simple :). In my book Deployment from Scratch I show people how to run Rails on a cheap VPS with a couple hundreds lines of Bash.

Just Ruby + chruby + Puma + systemd (and optional systemd socket activation).

I include a scripted demo (so you don't have to do it yourself) which demonstrates all of the this:

- Setting up a git-pust deployment for Ruby applications

- Using chruby to automate installing requested Ruby versions

- Configuring NGINX as a proxy using UNIX sockets

- Setting up systemd socket activation for graceful restarts

- Configuring NGINX to serve static assets

- Configuring NGINX to proxy WebSockets connections for Action Cable

- Automatic SSL/TLS certificates with Let's Encrypt

- Redirecting HTTP traffic and subdomains to main domain over HTTPS

- Running PostgreSQL and Redis on the same server

- Building a custom SELinux module

- Configuring firewall

- Setting up automatic weekly system update

- Setting up log rotation for NGINX and PostgreSQL logs and max limit for system log

- Doing application backups and restores

- Creating admin tasks

Although it sounds like a lot, the demo is reasonably small and clean so you can go through all the files in 2 hours.

I think people many times complicate what they don't need to complicate...