After some further investigation, this problem is probably not Ubuntu-specific
but originated in upstream Debian and was cherry-picked as part of these
changes:
http://launchpadlibrarian.net/433311114/dpkg_1.19.0.5ubuntu2.1_1.19.0.5ubuntu2.2.diff.gz
These changes include attempts to avoid trigger loops. One of the
triggers is ldconfig (see /var/lib/dpkg/info/libc-bin.triggers). It
seems that the changes have caused certain triggers to be postponed too
much. If a package states it depends (directly or indirectly) on a
library, one expects that this library is not just unpacked, but also
available at the moment the package enters its setup phase.
We have also tried to move python-augeas to Pre-Depends: instead in the
hopes of causing the ldconfig to be triggered before the postinst is
invoked, but this makes no difference.
** Description changed:
Seen on: Ubuntu 18.04.3 LTS
dpkg version: 1.19.0.5ubuntu2.3 (also in 1.19.0.5ubuntu2.2)
Regression compared to dpkg 1.19.0.5ubuntu2.1
-
To reproduce this:
1. You need a package that depends on a library for running a script in its
postinst hook. For instance, the attached minimal package has `Depends:
python-augeas`, and tries to do “from augeas import Augeas” in a script invoked
from the postinst hook. (It does nothing else.)
2. Make sure the dependent library is not yet installed. In this example:
libaugeas0, which is a dependency of python-augeas.
3. apt-get install the package. For the attached exmple, you can use `dpkg
-i`, followed by `apt-get -f install`.
Result:
Setting up the-package (1.2.3ubuntu1-2-1) ...
Traceback (most recent call last):
- File "/usr/lib/the-package/setup-package.py", line 3, in <module>
- from augeas import Augeas
- File "/usr/lib/python2.7/dist-packages/augeas.py", line 78, in <module>
- class Augeas(object):
- File "/usr/lib/python2.7/dist-packages/augeas.py", line 82, in Augeas
- _libaugeas = _dlopen("augeas")
- File "/usr/lib/python2.7/dist-packages/augeas.py", line 75, in _dlopen
- raise ImportError("Unable to import lib%s!" % args[0])
+ File "/usr/lib/the-package/setup-package.py", line 3, in <module>
+ from augeas import Augeas
+ File "/usr/lib/python2.7/dist-packages/augeas.py", line 78, in <module>
+ class Augeas(object):
+ File "/usr/lib/python2.7/dist-packages/augeas.py", line 82, in Augeas
+ _libaugeas = _dlopen("augeas")
+ File "/usr/lib/python2.7/dist-packages/augeas.py", line 75, in _dlopen
+ raise ImportError("Unable to import lib%s!" % args[0])
ImportError: Unable to import libaugeas!
dpkg: error processing package the-package (--configure):
- installed the-package package post-installation script subprocess returned
error exit status 1
+ installed the-package package post-installation script subprocess returned
error exit status 1
-
- Simply running apt-get -f install afterwards will succeed and run the
postinst script.
+ Simply running apt-get -f install afterwards will succeed and run the
+ postinst script.
The cause of this problem seems to be that any invocations of `ldconfig`
during the installation of the dependent libraries, do nothing at all.
When adding `ldconfig -p >/tmp/ldconfig-output` to the postinst hook, one can
see that neither libaugeas0 nor any other libraries that were just installed,
are in the ldconfig cache at the moment the script is invoked.
- Even when adding an explicit `ldconfig` in the postinst script before running
the python script, it still fails.
- Very curiously, calling `ldconfig -v >/dev/null` instead, somehow makes
ldconfig work. This seems to indicate that there is some problem with I/O
redirection, but for some reason the `-v` is also essential.
+
+ Even when trying to perform an ugly workaround by adding an explicit
`ldconfig` invocation in the postinst script before running the python script,
it still fails.
+ Very curiously, calling `ldconfig -v >/dev/null` instead, somehow makes
ldconfig work. This is probably because ldconfig calls are actively blocked in
maintainer scripts, but adding the argument and redirect circumvents this
block...
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https://bugs.launchpad.net/bugs/1851675
Title:
dpkg fails to properly invoke ldconfig
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