[Duplicity-talk] Problems with Duplicity cache synchronization

[Joshua M. Boniface]

Hello list!

We have an issues from time to time where duplicity tries to check the
synchronization between the cache and back-end.
It ask for the private key passphrase (key which isn't installed) and
the backup fails

The error:

> Synchronizing remote metadata to local cache...
> PASSPHRASE variable not set, asking user.
> GnuPG passphrase:

We do not want to installed the GPG private key on our hosts (only the
public one).
From our understanding, this key is only required to decrypt backups
that are stored encrypted in our Swift back-end.

I'd like to know if this kind of setup is supposed to work without any
issue. And what could cause the need of a synchronization?

Or is the synchronization a process which has to happens regularly (even
if the sync is actually good)?
If yes, what's the frequency/or reason triggering it?
This would make the presence of the private key on the hosts mandatory
to work with encrypted backups, correct?

We use duplicity 0.7.10 with duply 2.0.1.

Thank you,
Joshua