How to create a GNU Hello RPM package

This is a short hands-on tutorial on writing RPM files, suitable for an impatient person who wants to quickly step up to create very simple source and binary software packages. I assume familiarity with using pre-made RPM packages, and with the FOSS software building process.

For more information on how to create RPM files, including more detailed tips, see How to create an RPM package.

This tutorial demonstrates packaging of the GNU "Hello World" project. While 'Hello World" is a trivial program, the GNU project contains most of the usual peripheral components associated with a typical FOSS software distribution, including the configuration/build/install environment, documentation, internationalization, etc. As you will see, it's a reasonable vehicle to practice building RPMs on.

I wrote this tutorial when I worked through Christoph Wickert's IRC class on building RPMs using Rahul Sundaram suggestion of GNU "Hello World" as a test case. After I wrote up my experience, I 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. However, Christian told me he isn't planning to update his site, and I think 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.

Development environment

To build RPMs we need a set of development tools. This is a one-time-only setup, installed by running those commands from a system administration (root) account:

yum groupinstall development-tools
yum install rpm-build rpmdevtools

If you want to test the build procedure in the context of Fedora anonymous package build system, you need to configure your non-privileged account to be a member of the 'mock' group:

usermod -a -G mock <yourAccountName>

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 command

rpmdev-setuptree

sets up a RPM build area in your ~/rpmbuild. This directory will contain several subdirectories, for the project source code, RPM configuration files and for the resulting source and binary packages.

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 a preferred distribution form for most FOSS projects.

cd ~/rpmbuild/SOURCE
wget  http://ftp.gnu.org/gnu/hello/hello-2.5.tar.gz

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

cd ~/rpm/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.

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: 2.5
Release: 1
Summary: The "Hello World" program
License: GPLv3
URL: http://ftp.gnu.org/gnu/hello    
Source0: http://ftp.gnu.org/gnu/hello/hello-2.5.tar.gz
%description:
The "Hello World" program, done with all bells and whistles of a proper FOSS 
project, including configuration, build, internationalization, helpfiles, etc.

%changelog
* Tue Mar 30 2010 The Coon of Ty <Ty@coon.org> 2.5-1
- Initial version of the package

The Version should mirror 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 is being phased out, but it doesn't hurt to classify it in accordance to the list in /usr/share/doc/rpm-4.6.0/GROUPS.

The %changelog should document the work on preparing the RPM , and should include the version string to avoid rpmlint complains.

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

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

Since our program uses translations and internationalization, we are getting 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 unistallation of the package does not interfere with other software on the system:

• delete the 'dir' file in %install: rm -f $RPM_BUILD_ROOT/usr/share/info/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

A complete hello.spec file

Here's the initial version of hello.spec:

Name:           hello
Version:        2.5
Release:        1%{?dist}
Summary:        The "hello world" program from GNU

Group:          Applications/Text
License:        GPLv3
URL:            http://ftp.gnu.org/gnu/hello
Source0:        http://ftp.gnu.org/gnu/hello/hello-2.5.tar.gz
BuildRoot:      %{_tmppath}/%{name}-%{version}-%{release}-root-%(%{__id_u} -n)

BuildRequires: gettext
# Requires:       
Requires(post): info
Requires(preun): info

%description 
The "hello world" program from GNU, with bells and whistles


%prep
%setup -q


%build
%configure
make %{?_smp_mflags}


%install
rm -rf $RPM_BUILD_ROOT
make install DESTDIR=$RPM_BUILD_ROOT
%find_lang %{name}
rm -f $RPM_BUILD_ROOT/usr/share/info/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

%clean
rm -rf $RPM_BUILD_ROOT


%files -f %{name}.lang
%defattr(-,root,root,-)
%{_bindir}/hello
%doc %{_mandir}/man1/hello.1.gz
%doc %{_infodir}/%{name}.info.gz

%changelog
* Tue Mar 30 2010 The Coon of Ty <Ty@coon.org> 2.5-1
- 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, append the error messages to the rpmlint -I command 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.

mock -r fedora-12-i386 --rebuild ../SRPMS/hello-2.5-1.fc12.src.rpm