Fatal error with GPG after upgrade to Ubuntu 16.10

[Andrew France]

I upgraded from 16.04 to 16.10 with `do-release-upgrade` and now my backups fail with the output below. Unfortunately I don't really understand what the GNUPG output means and it's not clear from Googling if I can fix this issue.

$ duply triton backup
Start duply v1.11.3, time is 2016-11-02 10:29:43.
Using profile '/home/andrew/.duply/triton'.
Using installed duplicity version 0.7.06, python 2.7.12+, gpg 2.1.15 (Home: /home/andrew/.gnupg), awk 'GNU Awk 4.1.3, API: 1.1 (GNU MPFR 3.1.5, GNU MP 6.1.1)', grep 'grep (GNU grep) 2.25', bash '4.3.46(1)-release (x86_64-pc-linux-gnu)'.
Autoset found secret key of first GPG_KEY entry '8B999DFE' for signing.
Checking TEMP_DIR '/tmp' is a folder and writable (OK)
Test - Encrypt to '8B999DFE' & Sign with '8B999DFE' (FAILED)

Sorry. A fatal ERROR occured:

Encryption failed (Code 2).
gpg: using "8B999DFE" as default secret key for signing
[GNUPG:] KEY_CONSIDERED 5D116D08C821C44D5848F24252E8B2508B999DFE 2
[GNUPG:] KEY_CONSIDERED 5D116D08C821C44D5848F24252E8B2508B999DFE 0
[GNUPG:] KEY_CONSIDERED 5D116D08C821C44D5848F24252E8B2508B999DFE 0
[GNUPG:] PROGRESS need_entropy X 4 16
[GNUPG:] PROGRESS need_entropy X 16 16
[GNUPG:] BEGIN_SIGNING H8
[GNUPG:] PINENTRY_LAUNCHED 8099
gpg: signing failed: Inappropriate ioctl for device
[GNUPG:] BEGIN_ENCRYPTION 2 9
[GNUPG:] FAILURE sign-encrypt 83918950
gpg: /usr/bin/duply: sign+encrypt failed: Inappropriate ioctl for device

Hint:
  This error means that gpg is probably misconfigured or not working
  correctly. The error message above should help to solve the problem.
  However, if for some reason duply should misinterpret the situation you
  can define GPG_TEST='disabled' in the conf file to bypass the test.
  Please do not forget to report the bug in order to resolve the problem
  in future versions of duply.

ProblemType: Bug
DistroRelease: Ubuntu 16.10
Package: duply 1.11.3-1
Uname: Linux 4.8.3-x86_64-linode76 x86_64
ApportVersion: 2.20.3-0ubuntu8
Architecture: amd64
Date: Wed Nov 2 10:31:12 2016
PackageArchitecture: all
ProcEnviron:
 LANG=en_GB.UTF-8
 PATH=(custom, no user)
 TERM=screen-256color
 SHELL=/bin/bash
SourcePackage: duply
UpgradeStatus: Upgraded to yakkety on 2016-11-01 (0 days ago)

[Andrew France (andrew-avito)]

After following some random links from Launchpad I found this message: https://lists.launchpad.net/duplicity-team/msg02653.html

Which discusses whether setting `GPG_OPTS="--pinentry-mode loopback"` might fix it. I tried that and it does work.

I wish this information was easier to find. :(

[Adam Williamson (awilliamson)]

Still, that's no reason to close this as invalid. It's silly to suggest that everyone in the world who uses duply has to add this to their config manually once their GPG is new enough. Instead, duply should know that it has to use those options if gpg is 2.1 or newer...