IUS vs. Software Collections¶

Introduction¶

In 2013, Red Hat released a product called Software Collections (RHSCL). This product later got it's own community website. The front page has this statement:

Software Collections give you power to build, install, and use multiple versions of software on the same system, without affecting system-wide installed packages.

Here is our mission statement for the IUS Community project:

IUS is a community project that provides RPM packages for newer versions of select software for Enterprise Linux distributions.

Both projects seek to solve the same problem, but differ greatly in execution.

Types of Packages¶

IUS provides Safe Replacement Packages and Parallel Installable Packages.
SCL provides a unique kind of Parallel Installable Packages.

File Locations¶

Files from IUS packages are installed to similar locations as stock packages, such as /usr/bin, /usr/lib, /etc, /var, and so on.
Files from SCL packages are installed under /opt, /etc/opt, and /var/opt.

Usage¶

Usage of IUS packages are the same or very close to stock packages.

php -v
service mysqld start
mysql -V
python2.7 -V

Usage of SCL packages are very different from stock packages.

scl enable php54 "php -v"
service mysql55-mysqld start
scl enable mysql55 "mysql -V"
scl enable python27 "python -V"

Releases¶

IUS packages are updated in line with the upstream software project. This means that once upstream releases a new version of the corresponding release branch, we will begin building RPMs as soon as possible. It also means that once software is declared "End of Life" (EOL) by the upstream project, we remove it from our stable repositories.
The Product Life Cycle for Red Hat Software Collections (RHSCL) states that "Production Collections" are supported with security updates for three years. Major updates are grouped together and released as a new collection.
Software Collections from softwarecollections.org are community driven and have no guarantees. Please see this mailing list post.

SCL in base repositories¶

Generally, users have to go out of their way to use SCL packages. Subscribing to a RHSCL channel or installing the centos-release-scl package are needed to access SCL packages. An exception occurred when Red Hat released MySQL SCL packages into the 5.10 base channel. While this appears to be an isolated case, it important to note this occurred and it is not clear if Red Hat will do this again. For IUS users, this created confusion as there was a mysql55 package in both the base channel and IUS repository.