[Bug 2039873] Re: liblxc-dev was built with LXC_DEVEL=1 in Ubuntu 22.04 and later releases

[Andreas Hasenack]

I imported your noble debdiff and pushed to this branch:

https://code.launchpad.net/~ahasenack/ubuntu/+source/lxc/+git/lxc/+ref/noble-
lxc-drop-devel-2039873

If you run "git ubuntu clone lxc; cd lxc; git ubuntu remote add
ahasenack; git checkout noble-lxc-drop-devel-2039873" you should have a
local copy. Or if using just git, not git-ubuntu, follow the
instructions from the URL above.

Regarding the new d/t/build dep8 test:

"""
d/t/control:
Tests: build
Restrictions: allow-stderr superficial

d/t/build:
#!/bin/sh
# autopkgtest check: very basic checks to ensure that LXC package is in a good shape

set -eux

# ensure that LXC_DEVEL is 0
grep "LXC_DEVEL" meson.build | grep 0
"""


a) being marked as superficial won't block a migration if it fails (IIRC: at least, it's definitely not a hard error). And we do want this to "stop the line" if it fails, right?

b) it's checking something from the source code, which could be later
changed via d/rules during build. What I mean is that this is not the
place users will get the value of LXC_DEVEL from. We should be checking
the include file that gets installed on the user's system, either via
grep, or preferably a small C program that includes that version.h file
and checks the value of LXC_DEVEL.

c) A DEP8 test is awesome, thanks for that. But it might too close to a
release for such a check. Imagine an SRU gets sponsored, then reviewed,
then accepted, and then we get the DEP8 result that says "oops,
LXC_DEVEL=1 is leaking again". How about also checking it during package
build? I won't block the upload on this, though, but it would be good to
have I think, even if later.

What are your thoughts on (a) and (b)?

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https://bugs.launchpad.net/bugs/2039873

Title:
  liblxc-dev was built with LXC_DEVEL=1 in Ubuntu 22.04 and later
  releases

Status in lxc package in Ubuntu:
  Confirmed
Status in lxc source package in Jammy:
  New
Status in lxc source package in Mantic:
  New
Status in lxc source package in Noble:
  Confirmed

Bug description:
  [ Impact ]

  LXC 5.0.0 was built with LXC_DEVEL=1 set for Jammy. But for release
  build we should have LXC_DEVEL=0.

  LXC_DEVEL is a variable that appears in the /usr/include/lxc/version.h
  and then can be (and actually it is) used by other projects to detect
  if liblxc-dev is a development build or stable.

  Having LXC_DEVEL=1 makes problems for the users who want to build projects those are depend on liblxc
  from source (for example, LXD, go-lxc: https://github.com/canonical/lxd/pull/12420).

  Q: Why it was not a problem for so long?
  A: Because LXC API was stable for a long time, but recently we have extended liblxc API (https://github.com/lxc/lxc/pull/4260) and dependant package go-lxc was updated too (https://github.com/lxc/go-lxc/pull/166).
  This change was developed properly to be backward compatible with the old versions of liblxc. But, there is a problem. If LXC_DEVEL=1 then the macro check VERSION_AT_LEAST (https://github.com/lxc/go-lxc/blob/ccae595aa49e779f7ecc9250329967aa546acd31/lxc-binding.h#L7) is disabled. That's why we should *not* have LXC_DEVEL=1 for *any* release build of LXC.

  [ Test Plan ]

  Install liblxc-dev package and check /usr/include/lxc/version.h file
  LXC_DEVEL should be 0

  [ Where problems could occur ]

  Theoretically, build of a software which depends on liblxc-dev may start to fail
  if it assumes that LXC_DEVEL is 1.

  [ Other Info ]

  -

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