Base Server Configuration

[Mycobee]

Hi Kamal folks 👋

I love Kamal, and the idea of easy Rails deployments to servers. It has been a nice tool for many personal projects and clients.

Given Rails' solid history with security, I think the servers should also get a bit of attention, especially if end users are encouraged to deploy to one. I made a project called kamabian. The idea is a "convention over configuration" approach to bootstrapping a Debian/Ubuntu server before Kamal usage. It does some simple SSH hardening, no password logins, fail2ban, UFW rules, non-root docker, and unattended upgrades. It runs via Ansible in a container, but that is relatively easily to abstract away from the end user.

Not sure if this is something worth considering for the project, but I do believe in my heart of hearts it would be good for the project to have a "here is a plug-and-play tool to get your server to a place of sane defaults."

[nickhammond]

@Mycobee One approach is to run a few things in the docker-setup hook, which runs after Docker is installed on the server.

This PR is pretty conservative and just meant as a starting point #1404