

Apparently: https://fr.m.wikipedia.org/wiki/Rétention_de_sûreté_en_France
In French criminal law, “rétention de sûreté” is a procedure for placing prisoners who have served their sentence, but who present a very high risk of reoffending because they generally suffer from a serious personality disorder, in a socio-medico-judicial security center. This measure is limited to convictions for the most serious crimes, in particular sex crimes, and must be expressly provided for in the sentencing decision
Translated with DeepL
I couldn’t find an English source, even the English wiki article on preventive detention doesn’t list France.
You should try pangolin. It uses Traefik instead of Caddy under the hood but it automates approximately 80 % of setup. It’s what I use for my setup.
https://fossorial.io/