How-to guides

Guide	When
Recover full outage	Host mostly down
Recover Nginx	HTTPS/all web apps dead
Recover MariaDB	App DB failures
Recover mail (Postfix/Dovecot)	SMTP/IMAP broken
Recover an app service	vaultwarden, ntfy, etc.
Recover Docker container	Non-ynh container down
Unban an IP in Fail2Ban	Locked out / false positive
Respond to security incident	Suspected compromise
Backup and restore	yunohost backup + off-site
Upgrade system and apps	Patching
Add a domain	New hostname
Renew certificate	TLS issues
Routine maintenance	Daily/weekly pass