Create a SPIRE Hardening Guide

[v0lkan]

Right now, when you search for "SPIRE Hardening Guide" you get two (relevant) hits:

• Helm Charts Hardened
• SPIKE Production Guide / Hardening Section

The former does not directly describe how to harden SPIRE, it suggests to enable recommendations (which does hardening, yet the reader would need to make an educated guess); and the charts do not apply to bare-metal setups.

The latter, though, can be salvaged, and extended for a SPIRE-centric document.
In the final document, we should also mention why helm-charts-hardened recommendations matter, and what they do to make the deployment secure and robust (especially for lighter, more resource-contentious environments, like edge deployments)

--

I'm taking the initiative and assigning this issue to myself.

[v0lkan]

When ready, I'll mention several usual suspects for a peer review.

[v0lkan]

Note to link the Bottom Turtle Reference architecture once it's ready.

[v0lkan]

Note (so that I won't forget): while at that, it's important to have a "Day 2 Setup Guide" too. --- All of the docs are about deploying SPIRE in some sort of setup, and nothing talks about "what happens next".