Usrmerge in bookwork images causes issues with dpkg-query -S

[ederuiter]

Not sure where this issue belongs as it there are a couple of issues that all compound to this issue.

I came across this issue when debugging an issue with the latest phpmyadmin docker image.

This image installs some dev packages and compiles a couple of php extensions and then uses ldd on the resulting extensions .so files together with dpkg-query -S to find the packages that need to be kept after the build.

Note: this pattern does seem to be used by more php based containers.

The issue is that the ldd output points to /lib/x86_64-linux-gnu but most packages don't install files to /lib, but to /usr/lib .. and dpkg-query does not detect that these are effectively the same files (see https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=858331 and https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=848622)

The reason the ldd output point to /lib/x86_64-linux-gnu instead of /usr/lib/x86_64-linux-gnu because both of the paths are in /etc/ld.so.conf.d/x86_64-linux-gnu.conf and it appears the first one take precedence

Removing the /lib/x86_64-linux-gnu line from the ld.so.conf fixes the ldd output; but does not fix the problem.

This is because some packages (for example libbz2-1.0) are still installing to /lib/ instead of /usr/lib so dpkg-query -S does not find these .. and worse even if we would lookup the realpath before calling dpkg-query -S it still does not find them as /usr/lib is the realpath

So in my opinion there are 3 issues:

1. dpkg-query does not handle soft links (ideally both the install path + given path should be normalized before comparing)
2. packages still install to /lib instead of /usr/lib
3. ld.so.conf should only list /usr/lib and not /lib (can only be done after issue 2 is fixed for all packages)

Imho fixing 1 would be the easiest as that would workaround issues 2 & 3.

[tianon]

Sorry for the delay here, I've been meaning to get back to this for days. 🙇

There's not really anything we can do here in the Docker image itself -- we're faithfully following what the Debian project at large has decided, and the two bugs you've linked are unfortunately the appropriate place to track this bug/misfeature.

[ederuiter]

👌 Let's see what upstream says about this proposal: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=848622#27