APT dependency resolver: Missing python3-ldb Breaks: libldb2 ?
Hello,
I'm a DD myself, but employed by Univention GmbH. As such these are NOT
Debian packages, but our own builds. Nevertheless I want to understand
the underlying issue as I have seen it multiple times by now - even in
Debian.
Today I observed some APT behavior, which I was unable to explain at
first, but after some research make sense:
- System has old package versions installed:
libldb2:amd64 2:2.5.1-1
python3-ldb 2:2.5.1-1
- `apt-get install …` is used to install additional packages. Indirectly
they require newer version of
...: Depends: libldb2 (>= 2:2.5.2-1)
- This aborts refusing to upgrade `python3-ldb`, which declares
python3-ldb: Depends: libldb2 (= ${binary:Version})
- What I thinks is missing is some
libldb2: Breaks: python3-ldb (<< ${binary:Version})
# More details
This is from running the following command:
LC_ALL=C apt-get install \
-s \
-o Debug::pkgDepCache::Marker=yes \
-o Debug::pkgDepCache::AutoInstall=yes \
-o Debug::pkgProblemResolver=yes \
-o Debug::pkgProblemResolver::ShowScores=yes \
univention-s4-connector 2>&1 | less
which show this:
Show Scores
10000 univention-s4-connector:amd64 < none -> 14.0.10-2 @un puN >
...
35 python3-ldb:amd64 < 2:2.5.1-1 | 2:2.5.2-1 @ii umH >
...
30 libldb2:amd64 < 2:2.5.1-1 | 2:2.5.2-1 @ii umH >
...
8 samba-dsdb-modules:amd64 < 2:4.16.2-1 -> 2:4.16.2-1 @ii umU Ib >
Starting 2 pkgProblemResolver with broken count: 1
Investigating (0) samba-dsdb-modules:amd64 < 2:4.16.2-1 -> 2:4.16.2-1 @ii umU Ib >
Broken samba-dsdb-modules:amd64 Depends on libldb2:amd64 < 2:2.5.1-1 | 2:2.5.2-1 @ii umH > (> 2:2.5.2~)
Considering libldb2:amd64 30 as a solution to samba-dsdb-modules:amd64 8
MarkKeep samba-dsdb-modules:amd64 < 2:4.16.2-1 -> 2:4.16.2-1 @ii umU Ib > FU=0
Re-Instated libldb2:amd64
Re-Instated samba-dsdb-modules:amd64
Investigating (1) python3-ldb:amd64 < 2:2.5.1-1 | 2:2.5.2-1 @ii umH Ib >
Broken python3-ldb:amd64 Depends on libldb2:amd64 < 2:2.5.1-1 -> 2:2.5.2-1 @ii umU > (= 2:2.5.1-1)
Considering libldb2:amd64 30 as a solution to python3-ldb:amd64 35
I thinks it is here the APT decides to prioritize `python3-ldb` over
`libldb2` and prefers to not update both packages.
Added libldb2:amd64 to the remove list
Fixing python3-ldb:amd64 via keep of libldb2:amd64
MarkKeep libldb2:amd64 < 2:2.5.1-1A~5.0.0.202206171844 -> 2:2.5.2-1 @ii umU > FU=0
Is this a generic problem, which happens, when an upgrade is requested
to a lower-level library such as `libldb2`, but not the higher-level
package such as `python3-ldb`, when there is a same version dependency
between them?
python3-ldb: Depends: libldb2 (= ${binary:Version})
What is the correct fix? Add this?
libldb2: Breaks: python3-ldb (<< ${binary:Version})
LDB is here:
<https://salsa.debian.org/samba-team/ldb/-/blob/master/debian/control#L40-L42>
You can find even more details in my blog post at
<https://pmhahn.github.io/apt-dependency-resolver/>
Thanks in advance
Philipp
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