Chapter 3. Packaging software

An RPM package is a file containing other files and their metadata (information about the files that are needed by the system).

Specifically, an RPM package consists of the cpio archive.

The cpio archive contains:

Types of RPM packages

There are two types of RPM packages. Both types share the file format and tooling, but have different contents and serve different purposes:

The following procedures show how to list the utilities provided by the rpmdevtools package.

# yum install rpmdevtools

This section describes how to set up a directory layout that is the RPM packaging workspace by using the rpmdev-setuptree utility.

# yum install rpmdevtools

$ rpmdev-setuptree

$ tree ~/rpmbuild/
/home/<username>/rpmbuild/
|-- BUILD
|-- RPMS
|-- SOURCES
|-- SPECS
`-- SRPMS

5 directories, 0 files

The created directories serve these purposes:

You can understand a SPEC file as a recipe that the rpmbuild utility uses to build an RPM. A SPEC file provides necessary information to the build system by defining instructions in a series of sections. The sections are defined in the Preamble and the Body part. The Preamble part contains a series of metadata items that are used in the Body part. The Body part represents the main part of the instructions.

$ rpm -q bash
bash-4.2.46-34.el7.x86_64

In the context of RPM packaging, buildroot is a chroot environment. This means that the build artifacts are placed here using the same file system hierarchy as the future hierarchy in end user’s system, with buildroot acting as the root directory. The placement of build artifacts should comply with the file system hierarchy standard of the end user’s system.

The files in buildroot are later put into a cpio archive, which becomes the main part of the RPM. When RPM is installed on the end user’s system, these files are extracted in the root directory, preserving the correct hierarchy.

An rpm macro is a straight text substitution that can be conditionally assigned based on the optional evaluation of a statement when certain built-in functionality is used. Hence, RPM can perform text substitutions for you.

An example use is referencing the packaged software Version multiple times in a SPEC file. You define Version only once in the %{version} macro, and use this macro throughout the SPEC file. Every occurrence will be automatically substituted by Version that you defined previously.

$ rpm --eval %{_MACRO}

$ rpm --eval %{_bindir}
/usr/bin

$ rpm --eval %{_libexecdir}
/usr/libexec

On of the commonly-used macros is the %{?dist} macro, which signals which distribution is used for the build (distribution tag).

# On a RHEL 8.x machine
$ rpm --eval %{?dist}
.el8

To package new software, you need to create a new SPEC file.

There are two to achieve this:

The following procedure shows how to create a SPEC file for each of the three aforementioned Hello World! programs using the rpmdev-newspec utility.

fd. Examine the files:

+

The following procedure shows how to modify the output SPEC file provided by rpmdev-newspec for creating the RPMs.

You have now written an entire SPEC file for the required program.

For examples of SPEC file written in different programming languages, see:

This section shows an example SPEC file for the bello program that was written in bash. For more information about bello, see Section 2.1.1, “Source code examples”.

Name:           bello
Version:        0.1
Release:        1%{?dist}
Summary:        Hello World example implemented in bash script

License:        GPLv3+
URL:            https://www.example.com/%{name}
Source0:        https://www.example.com/%{name}/releases/%{name}-%{version}.tar.gz

Requires:       bash

BuildArch:      noarch

%description
The long-tail description for our Hello World Example implemented in
bash script.

%prep
%setup -q

%build

%install

mkdir -p %{buildroot}/%{_bindir}

install -m 0755 %{name} %{buildroot}/%{_bindir}/%{name}

%files
%license LICENSE
%{_bindir}/%{name}

%changelog
* Tue May 31 2016 Adam Miller <maxamillion@fedoraproject.org> - 0.1-1
- First bello package
- Example second item in the changelog for version-release 0.1-1

The BuildRequires directive, which specifies build-time dependencies for the package, was deleted because there is no building step for bello. Bash is a raw interpreted programming language, and the files are just installed to their location on the system.

The Requires directive, which specifies run-time dependencies for the package, include only bash, because the bello script requires only the bash shell environment to execute.

The %build section, which specifies how to build the software, is blank, because a bash does not need to be built.

For installing bello you only need to create the destination directory and install the executable bash script file there. Hence, you can use the install command in the %install section. RPM macros allow to do this without hardcoding paths.

This section shows an example SPEC file for the pello program written in the Python programming language. For more information about pello, see Section 2.1.1, “Source code examples”.

Name:           pello
Version:        0.1.1
Release:        1%{?dist}
Summary:        Hello World example implemented in Python

License:        GPLv3+
URL:            https://www.example.com/%{name}
Source0:        https://www.example.com/%{name}/releases/%{name}-%{version}.tar.gz

BuildRequires:  python
Requires:       python
Requires:       bash

BuildArch:      noarch

%description
The long-tail description for our Hello World Example implemented in Python.

%prep
%setup -q

%build

python -m compileall %{name}.py

%install

mkdir -p %{buildroot}/%{_bindir}
mkdir -p %{buildroot}/usr/lib/%{name}

cat > %{buildroot}/%{_bindir}/%{name} <←EOF
#!/bin/bash
/usr/bin/python /usr/lib/%{name}/%{name}.pyc
EOF

chmod 0755 %{buildroot}/%{_bindir}/%{name}

install -m 0644 %{name}.py* %{buildroot}/usr/lib/%{name}/

%files
%license LICENSE
%dir /usr/lib/%{name}/
%{_bindir}/%{name}
/usr/lib/%{name}/%{name}.py*

%changelog
* Tue May 31 2016 Adam Miller <maxamillion@fedoraproject.org> - 0.1.1-1
  - First pello package

The BuildRequires directive, which specifies build-time dependencies for the package, includes two packages:

The Requires directive, which specifies run-time dependencies for the package, includes only the python package. The pello program requires the python package to execute the byte-compiled code at runtime.

The %build section, which specifies how to build the software, corresponds to the fact that the software is byte-compiled.

To install pello, you need to create a wrapper script because the shebang is not applicable in byte-compiled languages. There are multiple options to accomplish this, such as:

This example shows creating a wrapper script in-line in the SPEC file to demonstrate that the SPEC file itself is scriptable. This wrapper script will execute the Python byte-compiled code by using a here document.

The %install section in this example also corresponds to the fact that you will need to install the byte-compiled file into a library directory on the system such that it can be accessed.

This section shows an example SPEC file for the cello program that was written in the C programming language. For more information about cello, see Section 2.1.1, “Source code examples”.

Name:           cello
Version:        1.0
Release:        1%{?dist}
Summary:        Hello World example implemented in C

License:        GPLv3+
URL:            https://www.example.com/%{name}
Source0:        https://www.example.com/%{name}/releases/%{name}-%{version}.tar.gz

Patch0:         cello-output-first-patch.patch

BuildRequires:  gcc
BuildRequires:  make

%description
The long-tail description for our Hello World Example implemented in
C.

%prep
%setup -q

%patch0

%build
make %{?_smp_mflags}

%install
%make_install

%files
%license LICENSE
%{_bindir}/%{name}

%changelog
* Tue May 31 2016 Adam Miller <maxamillion@fedoraproject.org> - 1.0-1
- First cello package

The BuildRequires directive, which specifies build-time dependencies for the package, includes two packages that are needed to perform the compilation build process:

The Requires directive, which specifies run-time dependencies for the package, is omitted in this example. All runtime requirements are handled by rpmbuild, and the cello program does not require anything outside of the core C standard libraries.

The %build section reflects the fact that in this example a Makefile for the cello program was written, hence the GNU make command provided by the rpmdev-newspec utility can be used. However, you need to remove the call to %configure because you did not provide a configure script.

The installation of the cello program can be accomplished by using the %make_install macro that was provided by the rpmdev-newspec command. This is possible because the Makefile for the cello program is available.

This paragraph is the procedure module introduction: a short description of the procedure.

The following example shows building source RPMs for the bello, pello, and cello projects.

$ cd ~/rpmbuild/SPECS/

8$ rpmbuild -bs bello.spec
Wrote: /home/<username>/rpmbuild/SRPMS/bello-0.1-1.el8.src.rpm

$ rpmbuild -bs pello.spec
Wrote: /home/<username>/rpmbuild/SRPMS/pello-0.1.2-1.el8.src.rpm

$ rpmbuild -bs cello.spec
Wrote: /home/<username>/rpmbuild/SRPMS/cello-1.0-1.el8.src.rpm

The following methods are vailable for building binary RPMs:

This section shows possible warnings and errors that can occur when checking RPM sanity on the example of the bello SPEC file and bello binary RPM.

$ rpmlint bello.spec
bello.spec: W: invalid-url Source0: https://www.example.com/bello/releases/bello-0.1.tar.gz HTTP Error 404: Not Found
0 packages and 1 specfiles checked; 0 errors, 1 warnings.

$ rpmlint ~/rpmbuild/SRPMS/bello-0.1-1.el8.src.rpm
bello.src: W: invalid-url URL: https://www.example.com/bello HTTP Error 404: Not Found
bello.src: W: invalid-url Source0: https://www.example.com/bello/releases/bello-0.1.tar.gz HTTP Error 404: Not Found
1 packages and 0 specfiles checked; 0 errors, 2 warnings.

$ rpmlint ~/rpmbuild/RPMS/noarch/bello-0.1-1.el8.noarch.rpm
bello.noarch: W: invalid-url URL: https://www.example.com/bello HTTP Error 404: Not Found
bello.noarch: W: no-documentation
bello.noarch: W: no-manual-page-for-binary bello
1 packages and 0 specfiles checked; 0 errors, 3 warnings.

This section shows possible warnings and errors that can occur when checking RPM sanity on the example of the pello SPEC file and pello binary RPM.

$ rpmlint pello.spec
pello.spec:30: E: hardcoded-library-path in %{buildroot}/usr/lib/%{name}
pello.spec:34: E: hardcoded-library-path in /usr/lib/%{name}/%{name}.pyc
pello.spec:39: E: hardcoded-library-path in %{buildroot}/usr/lib/%{name}/
pello.spec:43: E: hardcoded-library-path in /usr/lib/%{name}/
pello.spec:45: E: hardcoded-library-path in /usr/lib/%{name}/%{name}.py*
pello.spec: W: invalid-url Source0: https://www.example.com/pello/releases/pello-0.1.2.tar.gz HTTP Error 404: Not Found
0 packages and 1 specfiles checked; 5 errors, 1 warnings.

$ rpmlint ~/rpmbuild/SRPMS/pello-0.1.2-1.el8.src.rpm
pello.src: W: invalid-url URL: https://www.example.com/pello HTTP Error 404: Not Found
pello.src:30: E: hardcoded-library-path in %{buildroot}/usr/lib/%{name}
pello.src:34: E: hardcoded-library-path in /usr/lib/%{name}/%{name}.pyc
pello.src:39: E: hardcoded-library-path in %{buildroot}/usr/lib/%{name}/
pello.src:43: E: hardcoded-library-path in /usr/lib/%{name}/
pello.src:45: E: hardcoded-library-path in /usr/lib/%{name}/%{name}.py*
pello.src: W: invalid-url Source0: https://www.example.com/pello/releases/pello-0.1.2.tar.gz HTTP Error 404: Not Found
1 packages and 0 specfiles checked; 5 errors, 2 warnings.

$ rpmlint ~/rpmbuild/RPMS/noarch/pello-0.1.2-1.el8.noarch.rpm
pello.noarch: W: invalid-url URL: https://www.example.com/pello HTTP Error 404: Not Found
pello.noarch: W: only-non-binary-in-usr-lib
pello.noarch: W: no-documentation
pello.noarch: E: non-executable-script /usr/lib/pello/pello.py 0644L /usr/bin/env
pello.noarch: W: no-manual-page-for-binary pello
1 packages and 0 specfiles checked; 1 errors, 4 warnings.

This section shows possible warnings and errors that can occur when checking RPM sanity on the example of the cello SPEC file and pello binary RPM.

$ rpmlint ~/rpmbuild/SPECS/cello.spec
/home/<username>/rpmbuild/SPECS/cello.spec: W: invalid-url Source0: https://www.example.com/cello/releases/cello-1.0.tar.gz HTTP Error 404: Not Found
0 packages and 1 specfiles checked; 0 errors, 1 warnings.

$ rpmlint ~/rpmbuild/SRPMS/cello-1.0-1.el8.src.rpm
cello.src: W: invalid-url URL: https://www.example.com/cello HTTP Error 404: Not Found
cello.src: W: invalid-url Source0: https://www.example.com/cello/releases/cello-1.0.tar.gz HTTP Error 404: Not Found
1 packages and 0 specfiles checked; 0 errors, 2 warnings.

$ rpmlint ~/rpmbuild/RPMS/x86_64/cello-1.0-1.el8.x86_64.rpm
cello.x86_64: W: invalid-url URL: https://www.example.com/cello HTTP Error 404: Not Found
cello.x86_64: W: no-documentation
cello.x86_64: W: no-manual-page-for-binary cello
1 packages and 0 specfiles checked; 0 errors, 3 warnings.