Joerg Jaspert 
Martin Ellis@Ganneff I didn’t know yubikeys could sign non-interactively. Is it just a regular Yubikey or is it one of the YubiHSM things?
@martiell It's a standard "Yubico.com Yubikey 4/5" (that's how it names itself in lsusb).
You need to turn off the "Confirm user presence" thingie to have it NOT require a human touching it.
@Ganneff Good to know, thanks.