"Not a tty" error in Alpine-based duplicity image
For anyone who struggles from the same problem, I found the answer thanks to the developr of duplyhttps://sourceforge.net/p/ftplicity/bugs/76/#74c5
In short, you need to add GPG_OPTS='--pinentry-mode loopback' starting with gpg 2.1 and add allow-loopback-pinentry to .gnupg/gpg-agent.conf
This brought me much closer to a working setup.