[libvirt PATCH] CONTRIBUTING: Include information on build dependencies

[Andrea Bolognani]

On Thu, 2020-04-23 at 21:30 -0400, Laine Stump wrote:
> BTW, I just went through this on a new Fedora 31 machine (AMD Ryzen 
> 3950x! w00t!!) that I had installed with "Fedora Workstation", and 
> thought it might be useful to list exactly what was still missing for 
> certain "developer build" tasks after running "dnf builddep libvirt" on 
> a clean OS install. I found that I also had to install the following:
> 
> 
> 1) dnf install make
> 
> 
> This was required (duh!) to build from source tar, but not a part of the 
> base OS install nor in Build-Requires (I guess it makes sense - what 
> self-respecting Linux distro doesn't have basic build tools like make in 
> the base install?)

Plenty! Especially in the age of containers, where everyone is
scrambling to bring down the size of the base install. And it makes
sense, too: if you're going to run Apache or something like that on
the system, it's really not necessary to have make available.

> 2) dnf install autoconf automake libtool
> 
> 
> These three were required (but not in base OS + "dnf builddep libvirt" 
> to do a successful "./autogen.sh --system && make check" (i.e. build 
> from a fresh git clone of the tree).
> 
> 
> Again, I can see why autoconf, automake, and libtool wouldn't be in the 
> specfile Build-Requires:, since they *aren't* required when building 
> from a source tar, which already includes the configure script and 
> Makefile.in's that are generated using autotools.

That is not entirely true: if you look at our spec file, you'll find

  # Default to skipping autoreconf.  Distros can change just this one line
  # (or provide a command-line override) if they backport any patches that
  # touch configure.ac or Makefile.am.
  %{!?enable_autotools:%global enable_autotools 0}

  %if 0%{?enable_autotools}
  BuildRequires: autoconf
  BuildRequires: automake
  BuildRequires: gettext-devel
  BuildRequires: libtool
  %endif

  %if 0%{?enable_autotools}
   autoreconf -if
  %endif

so we clearly anticipate the possibility of running autoreconf at
build time. Debian, for example, while obviously not using our spec
file, mandates this behavior for all its packages...

I think some packages are left out of build dependencies because they
are used by so many that you'd see them repeated all over the place.
Debian has a special package defined for this very purpose:

  https://packages.debian.org/sid/build-essential

As you can see, it includes gcc and make plus dpkg-dev (roughly
equivalent to rpmbuild, although to build most packages currently in
the archive you'll also want debhelper at the very least in addition
to that), but not autotools.

For Fedora, the closest I've found is

  sudo dnf groupinfo "C Development Tools and Libraries"
  Group: C Development Tools and Libraries
   Description: These tools include core development tools such as automake, gcc and debuggers.
   Mandatory Packages:
     autoconf
     automake
     binutils
     bison
     flex
     gcc
     gcc-c++
     gdb
     glibc-devel
     libtool
     make
     pkgconf
     strace
   Default Packages:
     ...
   Optional Packages:
     ...

which includes autotools but not rpmbuild, and has a very
inconvenient name :)

> 4) dnf install cppi dwarves python3-flake8
> 
> 
> These three were *not* required to successfully complete any build 
> operation, but parts of "make syntax-check" were skipped because they 
> weren't present (and so not having them might result in a developer 
> believing that their patches had passed "make syntax-check, when in fact 
> they had not).
> 
> 
> At least cppi and python3-flake8 can't be Build-Required: in the 
> specfile for building because they aren't available on RHEL8/CentOS8 (at 
> least not without EPEL - haven't checked there yet, but of course EPEL 
> packages aren't available in the official build environment, so it's 
> kind of irrelevant)(oh, and also make syntax-check isn't run as part of 
> building the rpms, so those programs are never run during an official 
> build anyway, i.e. adding them to the Build-Requires: of the specfile 
> would be a lie :-)

Yeah, we could easily list them as requirements on Fedora only, but
since we don't actually run syntax-check at package build time it
doesn't feel right.

> Anyway, does anyone think it's worth adding a short bit to this file 
> about these extra packages? Or should we keep this file simple and 
> rather let newcomers (and old timers who've forgotten and are setting up 
> a new machine) figure it out for themselves?

I'll post a follow-up that adds instructions for installing autotools
as a prerequisite. That will surely age well, now that the switch to
Meson is looming O:-)

I think I'll leave out the set of packages in 4), though. I don't
want the instructions to become too long, and I think even without
those packages we'll still catch most issues.

-- 
Andrea Bolognani / Red Hat / Virtualization