Lab Notes

Things I want to remember how to do.

Compiling Subversion Python 2 Bindings for CentOS 8

August 2, 2020

I recently needed to install Trac 1.4 on a CentOS 8 server. Trac 1.4 still uses Python 2 and while CentOS 8 supports Python 2, Python 3 is the default. I suspect this went into the decision not to offer any Python bindings for Subversion in the CentOS 8 repositories.

I also checked WANDisco, which typically has advanced versions of Subversion packaged for CentOS, but they did not have the Python bindings for Python 2, only Python 3.

As a result, I was forced to compile the bindings myself.

I started with a new CentOS 8 VM created just for this purpose, selecting the “Development Tools” and “RPM Development Tools” software groups for installation.

From there we create a user named mockbuild which will perform the actual build. This username is referenced in the source RPMs for CentOS 8 and prevents spurious error messages. Plus it’s a throwaway instance so it doesn’t really matter.

[root@localhost ~]# useradd -G wheel mockbuild
[root@localhost ~]# passwd mockbuild
[root@localhost ~]# dnf install yum-utils

We installed yum-utils as well to get yumdownloader. This tool will help us obtain the source RPMs.

[mockbuild@localhost ~]$ yumdownloader --source subversion
[mockbuild@localhost ~]$ rpm -ivh subversion-1.10.2-1.module_el8.0.0+45+75bba4f4.src.rpm
Updating / installing...
   1:subversion-1.10.2-1.module_el8.0.################################# [100%]

We are also going to need Python 2:

[mockbuild@localhost ~]$ sudo dnf install python2 python2-devel
[mockbuild@localhost ~]$ sudo alternatives --set python /usr/bin/python2

The next step is to install the dependencies. The yum-builddep tool can help us here:

[mockbuild@localhost ~]$ sudo dnf config-manager --set-enabled PowerTools
[mockbuild@localhost ~]$ sudo yum-builddep subversion
Package perl-generators-1.10-9.el8.noarch is already installed.
Package libtool-2.4.6-25.el8.x86_64 is already installed.
Package autoconf-2.69-27.el8.noarch is already installed.
Package gettext-0.19.8.1-17.el8.x86_64 is already installed.
Package systemd-239-30.el8_2.x86_64 is already installed.
Package zip-3.0-23.el8.x86_64 is already installed.
Package unzip-6.0-43.el8.x86_64 is already installed.
Package which-2.21-12.el8.x86_64 is already installed.
No matching package to install: 'utf8proc-devel'
No matching package to install: 'libserf-devel >= 1.3.0'
Not all dependencies satisfied
Error: Some packages could not be found.

For the dependencies which were not found, we’ll need to download and compile them ourselves. (In general, however, double check that the packages are not in a disabled repository like PowerTools.)

We’ll start with utf8proc-devel:

[mockbuild@localhost ~]$ yumdownloader --source utf8proc
[mockbuild@localhost ~]$ rpm -ivh utf8proc-2.1.1-4.module_el8.0.0+45+75bba4f4.src.rpm
[mockbuild@localhost ~]$ sudo yum-builddep utf8proc
Package gcc-8.3.1-5.el8.0.2.x86_64 is already installed.
Dependencies resolved.
Nothing to do.
Complete!
[mockbuild@localhost ~]$ cd rpmbuild/SPECS/
[mockbuild@localhost SPECS]$ rpmbuild -ba utf8proc.spec
# Output elided for brevity
[mockbuild@localhost SPECS]$ cd ../RPMS/x86_64/
[mockbuild@localhost x86_64]$ sudo rpm -ivh utf8proc-2.1.1-4.el8.x86_64.rpm utf8proc-devel-2.1.1-4.el8.x86_64.rpm
[sudo] password for mockbuild:
Verifying...                          ################################# [100%]
Preparing...                          ################################# [100%]
Updating / installing...
   1:utf8proc-2.1.1-4.el8             ################################# [ 50%]
   2:utf8proc-devel-2.1.1-4.el8       ################################# [100%]

Next the libserf-devel library:

[mockbuild@localhost x86_64]$ cd
[mockbuild@localhost ~]$ yumdownloader --source libserf
[mockbuild@localhost ~]$ rpm -ivh libserf-1.3.9-8.module_el8.0.0+45+75bba4f4.src.rpm
Updating / installing...
   1:libserf-1.3.9-8.module_el8.0.0+45################################# [100%]
[mockbuild@localhost ~]$ sudo yum-builddep libserf
# Eliding 24 packages installed
[mockbuild@localhost ~]$ cd rpmbuild/SPECS/
[mockbuild@localhost SPECS]$ rpmbuild -ba libserf.spec
# Eliding output for brevity
[mockbuild@localhost SPECS]$ cd ../RPMS/x86_64/
[mockbuild@localhost x86_64]$ sudo rpm -ivh libserf-1.3.9-8.el8.x86_64.rpm libserf-devel-1.3.9-8.el8.x86_64.rpm
Verifying...                          ################################# [100%]
Preparing...                          ################################# [100%]
Updating / installing...
   1:libserf-1.3.9-8.el8              ################################# [ 50%]
   2:libserf-devel-1.3.9-8.el8        ################################# [100%]

Ok, we are getting good at this. Let’s see how we are with the dependencies for subversion:

[mockbuild@localhost ~]$ sudo yum-builddep subversion
Error:
 Problem: conflicting requests
  - package junit-1:4.12-9.module_el8.0.0+30+832da3a1.noarch is filtered out by modular filtering
(try to add '--skip-broken' to skip uninstallable packages or '--nobest' to use not only best candidate packages)

We have a package that is available somewhere but is being filtered. Let’s track it down:

[mockbuild@localhost SPECS]$ dnf module provides junit
Last metadata expiration check: 0:37:17 ago on Wed 15 Jul 2020 06:31:36 AM EDT.
junit-1:4.12-9.module_el8.0.0+30+832da3a1.noarch
Module   : javapackages-tools:201801:8000020190628172923:b07bea58:x86_64
Profiles :
Repo     : PowerTools
Summary  : Tools and macros for Java packaging support
[mockbuild@localhost SPECS]$ dnf module list javapackages-tools
Last metadata expiration check: 0:39:15 ago on Wed 15 Jul 2020 06:31:36 AM EDT.
CentOS-8 - PowerTools
Name                             Stream               Profiles              Summary
javapackages-tools               201801               common                Tools and macros for Java packaging support

Hint: [d]efault, [e]nabled, [x]disabled, [i]nstalled
[mockbuild@localhost SPECS]$ sudo dnf module install javapackages-tools:201801/common

With that last dependency is resolved, yum-builddep subversion finishes successfully and we are ready to build subversion.

Except that we have a small diversion in the form of a cautionary tale of a developer who failed to thoroughly read the documentation beforing diving in. The source RPM has installed the files in the rpmbuild/ directory. The rpmbuild/SPECS/subversion.spec file contains the details about how to build the software and the RPMs. At the top of this file are a number of directives configuring the build:

[mockbuild@localhost ~]$ head rpmbuild/SPECS/subversion.spec
# set to zero to avoid running test suite

%bcond_without kwallet
%bcond_without python2
%bcond_with python3
%bcond_without bdb
%bcond_without tests
%bcond_without pyswig

%ifarch %{power64} s390x

Originally I naively tried editing the subversion.spec file e.g. changing %bcond_without python2 to %bcond_with python2. Unfortunately (for me), the %bcond directives work the opposite of the way my intuition thought. So I was disabling Python 2 when I thought I was enabling it. See http://rpm.org/user_doc/conditional_builds.html for details.

Furthermore, the %bcond directives are designed to create command line switches. So there is no need to edit the subversion.spec file at all.

(The worst part was that the build succeeded but took hours because I had’t disabled the unit tests. And I didn’t end up with the Python 2 bindings.)

So it turns out the spec file is configured to use Python 2 already. We are going to disable the tests and the kwallet integration via command line switches. So the correct command is:

[mockbuild@localhost SPECS]$ rpmbuild -ba subversion.spec --without kwallet --without tests

Finally we tar up the resulting RPMs for installation on the target server:

[mockbuild@localhost rpmbuild]$ cd RPMS/
[mockbuild@localhost RPMS]$ tar cvf svn-1.10.2.tar *
noarch/
noarch/subversion-javahl-1.10.2-1.el8.noarch.rpm
x86_64/
x86_64/utf8proc-2.1.1-4.el8.x86_64.rpm
x86_64/utf8proc-devel-2.1.1-4.el8.x86_64.rpm
x86_64/utf8proc-debugsource-2.1.1-4.el8.x86_64.rpm
x86_64/utf8proc-debuginfo-2.1.1-4.el8.x86_64.rpm
x86_64/libserf-1.3.9-8.el8.x86_64.rpm
x86_64/libserf-devel-1.3.9-8.el8.x86_64.rpm
x86_64/libserf-debugsource-1.3.9-8.el8.x86_64.rpm
x86_64/libserf-debuginfo-1.3.9-8.el8.x86_64.rpm
x86_64/subversion-1.10.2-1.el8.x86_64.rpm
x86_64/subversion-libs-1.10.2-1.el8.x86_64.rpm
x86_64/python2-subversion-1.10.2-1.el8.x86_64.rpm
x86_64/subversion-devel-1.10.2-1.el8.x86_64.rpm
x86_64/subversion-gnome-1.10.2-1.el8.x86_64.rpm
x86_64/mod_dav_svn-1.10.2-1.el8.x86_64.rpm
x86_64/subversion-perl-1.10.2-1.el8.x86_64.rpm
x86_64/subversion-ruby-1.10.2-1.el8.x86_64.rpm
x86_64/subversion-tools-1.10.2-1.el8.x86_64.rpm
x86_64/subversion-debugsource-1.10.2-1.el8.x86_64.rpm
x86_64/subversion-debuginfo-1.10.2-1.el8.x86_64.rpm
x86_64/subversion-libs-debuginfo-1.10.2-1.el8.x86_64.rpm
x86_64/python2-subversion-debuginfo-1.10.2-1.el8.x86_64.rpm
x86_64/subversion-devel-debuginfo-1.10.2-1.el8.x86_64.rpm
x86_64/subversion-gnome-debuginfo-1.10.2-1.el8.x86_64.rpm
x86_64/mod_dav_svn-debuginfo-1.10.2-1.el8.x86_64.rpm
x86_64/subversion-perl-debuginfo-1.10.2-1.el8.x86_64.rpm
x86_64/subversion-ruby-debuginfo-1.10.2-1.el8.x86_64.rpm
x86_64/subversion-tools-debuginfo-1.10.2-1.el8.x86_64.rpm

Now, on the target server, we install the version of Subversion we compiled. We do this because the Python bindings and Subversion need to be the same version. Then we prevent dnf from updating the subversion package and creating an issue.

[root@target x86_64]# rpm -ivh subversion-1.10.2-1.el8.x86_64.rpm \
subversion-libs-1.10.2-1.el8.x86_64.rpm \
utf8proc-2.1.1-4.el8.x86_64.rpm  \
mod_dav_svn-1.10.2-1.el8.x86_64.rpm \
python2-subversion-1.10.2-1.el8.x86_64.rpm
Verifying...                          ################################# [100%]
Preparing...                          ################################# [100%]
Updating / installing...
   1:utf8proc-2.1.1-4.el8             ################################# [ 20%]
   2:subversion-libs-1.10.2-1.el8     ################################# [ 40%]
   3:subversion-1.10.2-1.el8          ################################# [ 60%]
   4:mod_dav_svn-1.10.2-1.el8         ################################# [ 80%]
   5:python2-subversion-1.10.2-1.el8  ################################# [100%]
[root@target dnf]# cd /etc/dnf
[root@target dnf]# cp dnf.conf dnf.conf.in
[root@target dnf]# vi dnf.conf
[root@target dnf]# diff dnf.conf.in dnf.conf
6a7
> exclude=subversion subversion-libs mod_dav_svn