The new stretch-slim images include a line like this in the Dockerfile to determine whether or not to install gnupg2 and dirmngr:
$(command -v gpg > /dev/null || echo 'gnupg2 dirmngr')
These packages are later purged, but because of apt (?), the dependencies of gnupg2 are not removed. To demonstrate:
❯ docker run --rm -it debian:stretch-slim bash
root@45ffcfc8aad0:/# apt-get update
...
root@45ffcfc8aad0:/# apt-get install -y --no-install-recommends gnupg2
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
gnupg gnupg-agent libassuan0 libksba8 libnpth0 libreadline7 libsqlite3-0 pinentry-curses readline-common
Suggested packages:
parcimonie xloadimage dbus-user-session libpam-systemd pinentry-gnome3 scdaemon pinentry-doc readline-doc
Recommended packages:
dirmngr gnupg-l10n
The following NEW packages will be installed:
gnupg gnupg-agent gnupg2 libassuan0 libksba8 libnpth0 libreadline7 libsqlite3-0 pinentry-curses readline-common
0 upgraded, 10 newly installed, 0 to remove and 0 not upgraded.
Need to get 2977 kB of archives.
After this operation, 6081 kB of additional disk space will be used.
...
root@45ffcfc8aad0:/# apt-get purge -y --auto-remove gnupg2
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
gnupg2*
0 upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
After this operation, 316 kB disk space will be freed.
(Reading database ... 6472 files and directories currently installed.)
Removing gnupg2 (2.1.18-8~deb9u1) ...
This has a few effects:
gnupg and its dependencies remain installed taking up space.- This
gnupg doesn't work in a lot of cases because dirmngr will have been removed.
- The
command -v gpg test done originally doesn't help to determine whether one should install gnupg2 and dirmngr anymore, since the command is still available.
I'm not sure whether the solution is to install gnupg instead of gnupg2 or to explicitly install both packages so that both are later removed.
The new
stretch-slimimages include a line like this in the Dockerfile to determine whether or not to installgnupg2anddirmngr:These packages are later purged, but because of apt (?), the dependencies of
gnupg2are not removed. To demonstrate:This has a few effects:
gnupgand its dependencies remain installed taking up space.gnupgdoesn't work in a lot of cases becausedirmngrwill have been removed.command -v gpgtest done originally doesn't help to determine whether one should installgnupg2anddirmngranymore, since the command is still available.I'm not sure whether the solution is to install
gnupginstead ofgnupg2or to explicitly install both packages so that both are later removed.