terraform: automate deployment

[Ivshti]

A lot of things were done on the fly on the current setup and not automated.

Automate them:

• setup the swarm on all the swarm servers, deploy the initial stack (the registry) by running beamup-sync-and-deploy
• swarm syncing through ssh (to allow the dokku plugin to trigger syncs); to implement this, just add to .ssh/authorized_keys on the swarm manager: command="beamup-sync-and-deploy",restrict,permitopen="localhost:5000" KEY dokku@stremio-addon-deployers, where the key is the main key of the deployer
• service for a ssh tunnel of port 5000, opened from the deployer to the swarm manager, so that the deployer can access the registry that's running on the swarm manager
• nginx logrotate (comes preinstalled + proper config)
• install the dokku plugin: dokku-plugins/beamup-trigger-swarm-sync - symlinking to /var/lib/dokku/plugins/enabled should do the job
• cron script to run docker prune and registry garbage-collect on the deployer (docker prune may be needed on the swarm servers too)
• disable swap: can cause issues with docker; although this might be sufficient: 0caa93b
• ssh hardening: do not permit root login, disable password login, create user beamup + ssh keys, login
• iptables/iptables-restore setup
• configurable domain; take the domain as a input option