I’ve recently begun packaging my custom builds of known software I use on my Linux setup.
Creating packages for Arch-based distros requires a description file called
PKGBUILD, which lists several metadata. Two of the important ones are
depends and makedepends.
depends: Packages or libraries the package depends on to run. In other words, the runtime dependencies.makedepends: Packages or libraries the package depends on to build. In other words, the compile-time dependencies.
These two are often overlooked in part by PKGBUILD writers. Because, “hey, it built and ran fine on my machine!”
Don’t do that.
The dependencies might be already present on your system, either explicitly installed or brought in as a dependency by another package. As such, you wouldn’t know what exactly will be required by other setups.
A way to determine the dependencies would be to test the PKGBUILDs on a fresh
install. But using a separate system with only base packages and then adding
the dependencies one at a time can be a pain.
An alternative is to make them in chroot. Think of it as containerised Arch Linux system with no access to the files(including packages) on your host system. The ArchWiki has a guide on this, so go over there for the tutorial. Let me show you what it would look like in practice.
Take the example of the slock-royarg-git package. Below are its dependencies:
depends=('libxcrypt' 'libxrandr' 'libxinerama' 'libxft')
makedepends=('git')
If we remove all dependencies(except git, as that is required to fetch the
source in the first place), and try to build, we will hit an error:
slock.c:20:10: fatal error: X11/extensions/Xrandr.h: No such file or directory
20 | #include <X11/extensions/Xrandr.h>
| ^~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
make: *** [Makefile:19: slock.o] Error 1
So we can figure out the compile-time dependencies, but what about the runtime dependencies? We run:
makechrootpkg -c -n -r $CHROOT
The -n flag additionally runs namcap, which checks for packaging
issues. If we miss a runtime dependency, namcap will produce the following
messages:
slock-royarg-git E: Dependency libxft detected and not included (libraries ['usr/lib/libXft.so.2'] needed in files ['usr/bin/slock'])
slock-royarg-git E: Dependency libxcrypt detected and not included (libraries ['usr/lib/libcrypt.so.2'] needed in files ['usr/bin/slock'])
slock-royarg-git E: Dependency libxrandr detected and not included (libraries ['usr/lib/libXrandr.so.2'] needed in files ['usr/bin/slock'])
slock-royarg-git E: Dependency libxinerama detected and not included (libraries ['usr/lib/libXinerama.so.1'] needed in files ['usr/bin/slock'])
So you’ve now figured out the package dependencies and made sure that it will build and run as expected on other systems.