Shared Development with Red Hat Software Collections
Mike Guerette recently posted an announcement on the Developer Blog that Red Hat Software Collections 1.0 is now generally available.
What is Software Collections and what value does it provide to developers?
In a nutshell, Software Collections allows multiple versions of a software ecosphere to be installed on a machine. For example, with Software Collections you can have Perl 5.10, Perl 5.14, and Perl 5.18 installed on a RHEL 6 system. Perl 5.10 is the version that comes with the Linux distribution while Perl 5.16 is available via Software Collections.
While RHEL is a very stable platform, it receives some criticism for lagging behind other Linux distributions in what versions of developer tools are available for various programming languages. This forces developers using RHEL 6 to develop and deploy software with an old, or some would say “ancient,” version of their language tools. Software Collections now provides an easy mechanism for alleviating the pain associated with working with older tools.
Most common languages used by developers on Linux have tools for installing multiple versions of developer tools and libraries so that developers can develop and test their code against different versions of the language. For example, Perl developers can use Perlbrew; Python developers can use VirtualEnv or PythonBrew; Ruby developers can use rvm or rbenv; and PHP developers can use php-version.
These are valuable tools in that they let the developer manage their own multiple installations of the environment needed for the language they’re working in.
The caveat of using these tools directly is that they don’t allow installation of multiple versions of a language for use system-wide. They only provide multiple versions for an individual user. If multiple Ruby developers, for example, are using a RHEL 6 system to do development and want to test their work against multiple versions of the Ruby interpreter, they will each need to use ‘rvm’ or ‘rbenv’ to install the multiple versions of the Ruby interpreter and accompanying packages and utilities under their home directory. This results in obvious redundancy and lost productivity, not to mention wasted disk space.
The best way to install something for use system-wide is via RPM packages and that is what Software Collections provide.
Putting Software Collections to work
Once you have your system configured to install software from the Red Hat Software Collections repository, you can begin installing packages. The package names have the collection name as a prefix. So, to install the python package for the Python 2.7 collection, you should run:
yum install python27-python
To use the new version of Python, you leverage the scl enable command. The scl enable command both activates the environment for the named collection and runs a specific command in that environment. For example:
scl enable python27 bin/script.py
At Bluehost where I am a programmer, we heavily use Perl. The version of Perl that ships with EL6 (5.10) was originally released in 2007 and there have been four major releases (5.12, 5.14, 5.16, and 5.18) since then. We’ve successfully leveraged Software Collections to deploy Perl 5.14 and Perl 5.16 into our development environments and will soon be using it in production.
In addition to languages like Python, Perl, PHP, and Ruby, there are Software Collection repositories for newer versions of the PostgreSQL, MySQL, and MariaDB relational database packages.
Building additional Software Collection packages
The Software Collection repositories don’t include all the packages you may want. For example, the Perl 5.16 repository includes the “core” modules and a few commonly-used modules like DBI and HTTP::Tiny. In most cases, you’re going to need to build more packages to install. That will be covered in a future Developer Blog article.