How to Create a GNU Hello World RPM Package

This is a short hands-on tutorial on writing RPM files, showing how to quickly set up and create simple source and binary software packages. It assumes some familiarity with using pre-made RPM packages, and with the FOSS building process.

For comprehensive information on how to create RPM files, including more detailed tips, refer to How to create an RPM package. If you plan to create an RPM package for the Fedora repository, follow the process for How to join the Fedora Package Collection Maintainers, including following the various Fedora guidance.

This tutorial demonstrates packaging of the GNU "Hello World" project. While the C program printing "Hello World" to standard output is trivial, the GNU version contains most of the usual peripheral components associated with a typical FOSS project, including the configuration/build/install environment, documentation, internationalization, etc. The GNU version, however, traditionally consists of a tar file containing the source code and configure/make scripts, but it does not include the packaging information. Therefore, it’s a reasonable vehicle to practice building RPMs on.

Development Environment

To build RPMs we need a set of development tools.

Make sure you run the following command as the root user!

This is a one-time-only setup, installed by running these commands from a system administration (root) account:

# dnf install fedora-packager @development-tools
Make sure you run the following command as the root user!

To be able to test the build procedure in a clean chroot you need to configure your non-privileged account to be a member of the 'mock' group:

# usermod -a -G mock <your username>

Those are the only commands requiring root privileges. All the remaining work should be done from your regular, non-privileged account, or even from a separate account created just for development work. Modern RPM-based systems, including Fedora, are set up to build and test RPM packages purely from within a non-privileged account. The following command sets up an RPM build area in your ~/rpmbuild directory. This directory will contain several subdirectories, for the project source code, RPM configuration files and for the resulting source and binary packages.

$ rpmdev-setuptree

Building a "Hello World" RPM

We need the source code of the project we are packaging, often referred to as the 'upstream' source. We will download it from the project’s website into the ~/rpmbuild/SOURCE directory. We are getting the compressed tarball archive, which happens to be the preferred distribution form for most FOSS projects.

$ cd ~/rpmbuild/SOURCES
$ wget http://ftp.gnu.org/gnu/hello/hello-2.10.tar.gz

The RPM package is configured by .spec files. We will create a template file hello.spec in the appropriate directory:

$ cd ~/rpmbuild/SPECS
$ rpmdev-newspec hello

Recent versions of Emacs and vi have .spec file editing modes which will also bring up a similar template upon creating a new file. So you can just use the following command for example to use the template automatically.

$ emacs hello.spec

Inside a Spec File

The fields in our .spec file need slight editing. Please follow the Fedora rules for these fields. In our case, the file might start as follows:

Name:     hello
Version:  2.10
Release:  1
Summary:  The "Hello World" program from GNU
License:  GPLv3+
URL:      https://www.gnu.org/software/hello/
Source0:  https://ftp.gnu.org/gnu/hello/hello-%{version}.tar.gz

%description
The "Hello World" program, done with all bells and whistles of a proper FOSS
project, including configuration, build, internationalization, help files, etc.

%changelog
* Thu Jul 07 2011 The Coon of Ty <Ty@coon.org> - 2.10-1
- Initial version of the package

The Version should mirror the upstream, while Release numbers our work within Fedora.

The first letter of the Summary should be uppercase to avoid rpmlint complaints.

It is your responsibility to check the License status of the software, by inspecting the source files and/or their LICENSE files, and/or by talking to the authors.

The Group tag was historically used to classify the package in accordance with the list in /usr/share/doc/rpm-`/GROUPS`. It is being phased out so you will not see it added by default. However, it doesn’t hurt to add it anyway.

The %changelog should document the work on preparing the RPM, especially if there are security and bug patches included on top of the base upstream source. Changelog data can be displayed by `rpm --changelog -q `, which is very useful for instance to find out if specific bug and security patches were included in the installed software, thanks to the diligent Fedora packagers who include this info with the relevant CVE numbers.

The %changelog entry should include the version string to avoid rpmlint complaints.

Multi-line sections like %changelog or %description start on a line under the directive, and end with a blank line.

Lines which aren’t needed (e.g. BuildRequires and Requires) can be commented out with a hash ('#') for now.

Many lines in the template don’t need to be changed at all in many cases, at least for the initial attempt.

Building the Package

We are ready for the first run to build source, binary and debugging packages:

$ rpmbuild -ba hello.spec

It will complain and list the unpackaged files, i.e. the files that would be installed in the system that weren’t declared as belonging to the package. We need to declare them in the %files section. Do not hardcode names like /usr/bin/, but use macros, like %{_bindir}/hello instead. The manual pages should be declared in the %doc subsection:

%doc %{_mandir}/man1/hello.1.*

This is an iterative process; after editing the .spec file, rerun rpmbuild.

Since our program uses translations and internationalization, we are seeing a lot of undeclared i18 files.

The recommended method to declare them is:

  • find the filenames in the %install step: %find_lang %{name}

  • add the required build dependencies: BuildRequires: gettext

  • use the found filenames %files -f %{name}.lang

If the program uses GNU info files, you need to make sure the installation and uninstallation of the package does not interfere with other software on the system, by using this boilerplate:

  • delete the dir file in %install:

$ rm -f %{buildroot}%{_infodir}/dir

  • Requires(post): info and Requires(preun): info

  • add those steps:

%post
/sbin/install-info %{_infodir}/%{name}.info %{_infodir}/dir || :

%preun
if [ $1 = 0 ] ; then
/sbin/install-info --delete %{_infodir}/%{name}.info %{_infodir}/dir || :
fi

This snippet is copied directly from here. That page contains solutions to many common packaging tasks. If possible, try to copy a solution from there instead of devising your own.

A Complete hello.spec File

Here’s the initial version of hello.spec:

Name:           hello
Version:        2.10
Release:        1%{?dist}
Summary:        The "Hello World" program from GNU

License:        GPLv3+
URL:            http://ftp.gnu.org/gnu/%{name}
Source0:        http://ftp.gnu.org/gnu/%{name}/%{name}-%{version}.tar.gz

BuildRequires: gettext

Requires(post): info
Requires(preun): info

%description
The "Hello World" program, done with all bells and whistles of a proper FOSS
project, including configuration, build, internationalization, help files, etc.

%prep
%autosetup

%build
%configure
make %{?_smp_mflags}

%install
%make_install
%find_lang %{name}
rm -f %{buildroot}%{_infodir}/dir

%post
/sbin/install-info %{_infodir}/%{name}.info %{_infodir}/dir || :

%preun
if [ $1 = 0 ] ; then
/sbin/install-info --delete %{_infodir}/%{name}.info %{_infodir}/dir || :
fi

%files -f %{name}.lang
%{_mandir}/man1/hello.1.*
%{_infodir}/hello.info.*
%{_bindir}/hello

%doc AUTHORS ChangeLog NEWS README THANKS TODO
%license COPYING

%changelog
* Tue Sep 06 2011 The Coon of Ty <Ty@coon.org> 2.10-1
- Initial version of the package

With this .spec file, you should be able to successfully complete the build process, and create the source and binary RPM packages.

Next you should check them for conformance with RPM design rules, by running rpmlint on the .spec file and all RPMs:

$ rpmlint hello.spec ../SRPMS/hello* ../RPMS/*/hello*

If there are no warnings or errors, we’ve succeeded. Otherwise, use rpmlint -i or rpmlint -I <error_code> to see a more verbose description of the rpmlint diagnostics.

The mock Builds

To check that the package build will succeed in the Fedora restricted build environment, check it with mock. The default mock configuration builds the package against Rawhide - the Fedora development branch.

$ mock --verbose ../SRPMS/hello-2.10-1.fc25.src.rpm

References

History

Przemek Klosowski wrote this tutorial when he worked through Christoph Wickert’s IRC session on building RPMs using Rahul Sundaram’s suggestion of GNU "Hello World" as a test case. After he wrote up his experience, he found out about the excellent and extensive How to create an RPM package page on this wiki, as well as the Christian Lyder Jacobsen’s website, which is unfortunately not available anymore. However, Christian isn’t planning to update his site, and it seemed that a 5-minute 'fast food' alternative to the more extensive article might suit some people. More in-depth information on using and building RPM packages is available from other sources.