RPM packaging: A simplified guide to creating your first RPM

RPM packaging: A simplified guide to creating your first RPM

The concept of RPM packaging can be overwhelming for first-timers because of the impression a steep learning curve is involved. In this article, I will demonstrate that building an RPM with minimal knowledge and experience is possible. Note that this article is meant as a starting point, not a complete guide to RPM packaging.

ASCII-based Tetris game

For my demonstration, I chose a simple ASCII-based Tetris game, written in C, and I made slight adjustments to ensure a relatively straightforward RPM build. I will use a game called Vitetris as my example, which you can download.

To ensure there are no errors when creating the RPM package, I remove references in the Makefile that change file permissions to root, in order to allow a non-root user to build the RPM. This modification is as follows:

$ cat Makefile |grep 'INSTALL '
INSTALL = install
#INSTALL = install -oroot -groot # non-root users building the rpm won't be able to set this and the RPM build will fail.

Once you have made this change, create a new gzipped tarball with the same name: vitetris-0.57.tar.gz.

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Preparing the environment

To install your development environment on a subscribed Red Hat Enterprise Linux (RHEL) 7 system, you need the following repositories to build your RPMs: rhel-7-server-rpms, rhel-7-server-extras-rpms, and rhel-7-server-optional-rpms.

You must have following packages installed:

# yum install -y rpm* gcc gpg* rng-tools

I use rpm* and gpg* because it makes the number of things to remember to install much more manageable.

Compiling the software manually

A large part of success with RPM packaging understanding the software you are working with. First, compiling software manually preferably is done as a non-root user. In this case, I am using the rpmbuilder user.

Start with extracting the gzipped tarball (vitetris-0.57.tar.gz), and then inspecting the README file. In this case, the README file doesn’t contain information about compiling your game from source code. As a general rule, open source software written in C is compiled with three steps: configure, make, and make install. However, it is worth just running make on its own to see whether the software will build.

As a non-root user, test to see whether running make is sufficient:

[rpmbuilder@rpm vitetris-0.57]$ make
generating src/src-conf.mk
./src-conf.sh 'cc' '' ''
...
Done.
Now run ./tetris (or make install)

To test the game, simply run ./tetris to see whether the game loads and can be played:

Running Tetris after building from source code

Creating GPG keys

Signing your RPM package adds an extra layer of trust to your packages. Therefore, to create GPG keys as the rpmbuilder user, you will need a session with root access to run rngd (to speed up the generation process) and a session with X11 forwarding as the rpmbuilder user.

As root, run:

# rngd -r /dev/urandom

If you get the following error:

Failed to init entropy source 2: Intel RDRAND Instruction RNG

Try:

# rngd -r /dev/urandom -o /dev/random -f

You must log into the host as rpmbuilder user with X11 forwarding (otherwise, the key generation will fail):

$ gpg --gen-key
...
Please select what kind of key you want:
(1) RSA and RSA (default)
(2) DSA and Elgamal
(3) DSA (sign only)
(4) RSA (sign only)
Your selection? 1
RSA keys may be between 1024 and 4096 bits long.
What keysize do you want? (2048) 
Requested keysize is 2048 bits
Please specify how long the key should be valid.
0 = key does not expire
<n> = key expires in n days
<n>w = key expires in n weeks
<n>m = key expires in n months
<n>y = key expires in n years
Key is valid for? (0) 
Key does not expire at all
Is this correct? (y/N) y

GnuPG needs to construct a user ID to identify your key.

Real name: RPM Build User
Email address: rpmbuilder@rpm
Comment: RPM Builder GPG Signing Key
You selected this USER-ID:
"RPM Build User (RPM Builder GPG Signing Key) <rpmbuilder@rpm>"

Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? O
You need a Passphrase to protect your secret key.
Prompt that is displayed if you have X11 forwarding turned on

This prompt will only appear if you have X11 forwarding turned on.

...
gpg: depth: 0 valid: 1 signed: 0 trust: 0-, 0q, 0n, 0m, 0f, 1u
pub 2048R/EEF6D9AD 2019-03-02
Key fingerprint = 6ED1 2456 B7ED EEC6 D0DF B870 444A 40A7 EEF6 D9AD
uid RPM Build User (RPM Builder GPG Signing Key) <rpmbuilder@rpm>
sub 2048R/D498F883 2019-03-02

If you need to export the key to be used within satellite for custom software or in your yum repo configuration, use the command:

$ gpg --armor --export
-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: GnuPG v2.0.22 (GNU/Linux)

Creating the RPM package for Vitetris

To build the RPM, first create the build tree and the spec file and place the source code in the right place:

$ rpmdev-setuptree
$ rpmdev-newspec rpmbuild/SPECS/vitetris.spec
rpmbuild/SPECS/vitetris.spec created; type minimal, rpm version >= 4.11.
$ cp vitetris-0.57.tar.gz rpmbuild/SOURCES/

Add initial details to the spec file

Provide the initial details:

Name:           vitetris
Version:        0.57
Release:        1%{?dist}
Summary:        ASCII based tetris game

License:        BSD
URL:            https://www.victornils.net/tetris/
Source0:        vitetris-0.57.tar.gz

BuildRequires:  gcc

Remove unnecessary sections

  • Delete the Requires section, as this software doesn’t have any dependencies.
  • Delete the %configure section, as this software can be built without configure (keep this if you need configure before you run make).

Add a description

You can add anything you like, but here is a suggestion:

%description
vitetris is a multiplayer ASCII-based Tetris game

Test the initial build

Test the build with the information just provided to see what errors appear:

$ rpmbuild -ba rpmbuild/SPECS/vitetris.spec
...
RPM build errors:
Installed (but unpackaged) file(s) found:
/usr/local/bin/tetris
/usr/local/share/applications/vitetris.desktop
/usr/local/share/doc/vitetris/README
/usr/local/share/doc/vitetris/licence.txt
/usr/local/share/pixmaps/vitetris.xpm

Add a list of files from the previous step to the spec file

You must add the list of files from the previous step to the %files section, as follows:

%files
/usr/local/bin/tetris
/usr/local/share/applications/vitetris.desktop
%doc /usr/local/share/doc/vitetris/README
/usr/local/share/doc/vitetris/licence.txt
/usr/local/share/pixmaps/vitetris.xpm

Notice that %doc was put in front of the README to identify it as an informational document. The RPM will still build without this.

Rerun the build

$ rpmbuild -ba rpmbuild/SPECS/vitetris.spec
Wrote: /home/rpmbuilder/rpmbuild/SRPMS/vitetris-0.57-1.el7.src.rpm
Wrote: /home/rpmbuilder/rpmbuild/RPMS/x86_64/vitetris-0.57-1.el7.x86_64.rpm
Wrote: /home/rpmbuilder/rpmbuild/RPMS/x86_64/vitetris-debuginfo-0.57-1.el7.x86_64.rpm
Executing(%clean): /bin/sh -e /var/tmp/rpm-tmp.AqR4Aq
+ umask 022
+ cd /home/rpmbuilder/rpmbuild/BUILD
+ cd vitetris-0.57
+ /usr/bin/rm -rf /home/rpmbuilder/rpmbuild/BUILDROOT/vitetris-0.57-1.el7.x86_64
+ exit 0

Sign the RPM package

Signing your RPM is as simple as running:

$ rpmsign --addsign /home/rpmbuilder/rpmbuild/RPMS/x86_64/vitetris-0.57-1.el7.x86_64.rpm 
Enter pass phrase: Pass phrase is good. 
/home/rpmbuilder/rpmbuild/RPMS/x86_64/vitetris-0.57-1.el7.x86_64.rpm:

If you get this error:

You must set "%_gpg_name" in your macro file

Set %_gpg_name with the public key value:

$ gpg --list-keys 
/home/rpmbuilder/.gnupg/pubring.gpg
-----------------------------------
pub 2048R/EEF6D9AD 2019-03-02
uid RPM Build User (RPM Builder GPG Signing Key) <rpmbuilder@rpm>
sub 2048R/D498F883 2019-03-02

$ echo "%_gpg_name EEF6D9AD" >> .rpmmacros

Try again:

$ rpmsign --addsign /home/rpmbuilder/rpmbuild/RPMS/x86_64/vitetris-0.57-1.el7.x86_64.rpm
Enter pass phrase: 
Pass phrase is good.
/home/rpmbuilder/rpmbuild/RPMS/x86_64/vitetris-0.57-1.el7.x86_64.rpm:

Test an install/uninstall of the RPM as root user

# rpm -i /home/rpmbuilder/rpmbuild/RPMS/x86_64/vitetris-0.57-1.el7.x86_64.rpm
warning: /home/rpmbuilder/rpmbuild/RPMS/x86_64/vitetris-0.57-1.el7.x86_64.rpm: Header V4 RSA/SHA1 Signature, key ID eef6d9ad: NOKEY

# /usr/local/bin/tetris

Installing the RPM as root

Uninstall the RPM:

# rpm -qa |grep tetris
vitetris-0.57-1.el7.x86_64
=# rpm -e vitetris-0.57-1.el7.x86_64
# /usr/local/bin/tetris
-bash: /usr/local/bin/tetris: No such file or directory

Conclusion

Depending on the software you intend to package, custom RPM packaging can be challenging. In this article, I aimed to do as little as possible to demonstrate that default settings are often enough to build an RPM.

To learn more, see Red Hat’s RPM packaging guide.

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