On Wed, 16 Oct 2013, Jeffrey Anderson wrote:

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> It seems to me that the "environment-modules" package available from EPEL
> can address many of your needs.
> 
> We use it to provide access to multiple versions of python, gcc, boost, gsl
> and many other tools and libraries, all without interfering with necessary
> system-level operations.  It is quite flexible, has a relatively low
> learning curve, and is widely used.  It allows users to easily switch back
> and forth between different versions of these tools.
> 
> Need python 2.7.2?
> 'module load python/2.7.2'
> 
> Want to switch to 2.6.4?
> 'module switch python/2.6.4'
> 
> Want to go back to the default system python?
> 'module unload python'
> 
> and so on.
> 
> Jeff
>

TUV and thus SL has had the technology known as "Software Collections" 
available in SL6 since 6.2 .
Software Collections installs packages in /opt/rh and thus preserves the base 
packages.  It provides a utility , scl , to "enable" these software 
collections.

TUV and thus SL has released "Devtoolset"  which provides newer GCC via 
"Software Collections".

Recently TUV and thus SL released "Software Collections" (uses scl but more 
than that) that provides

   mariadb55
   postgresql92
   ruby193
   mysql55
   python27
   nodejs010
   python33
   perl516
   php54

A README with info about yum repos for these packages is available from
ftp://sldist.fnal.gov/linux/scientific/6x/external_products/softwarecollections/README

More info from TUV is available at
https://access.redhat.com/site/documentation/Red_Hat_Software_Collections/

Note that Oleg responded to this thread with this info a few days ago.

The Software Collection python27 solves this problem completely.

-Connie Sieh

  >
> On Wed, Oct 16, 2013 at 1:11 PM, Yasha Karant <[log in to unmask]> wrote:
> 
>> On 10/16/2013 09:12 AM, Jim Fait wrote:
>> 
>>> I run into this all the time, as we have a large number of somewhat
>>> incompatible software packages that we are required to have.  What we have
>>> ended up doing is placing the real executable somewhere outside the normal
>>> path, and then putting a script with same name in /usr/local/bin or
>>> /opt/local/bin that encapsulates all of the foreign dependencies and
>>> environment.  That way, the particular package can live with its
>>> requirements alongside the production system, with very few problems seen
>>> by the end user.
>>> 
>>> Of course, this means writing a number of scripts, in our case a couple
>>> hundred, that stay fairly static with changes in the OS or the package in
>>> question, and that hide all of the nastiness that otherwise would happen,
>>> like a PATH environment variable 10 line long.
>>> 
>>> Hope this idea helps.
>>> 
>>> Jim
>>> 
>>> 
>> Your example is one of the accepted methods for enabling the idea of
>> polymorphism and encapsulation within an otherwise procedural imperative,
>> possibly structured, environment.  Assuming that what you are describing is
>> for both the build environment and the execution environment of the
>> environment/application being built, it should (in most cases) work.  And
>> -- it should be the norm when providing application building environments
>> that do NOT require a virtual machine (e.g., maintaining a "more modern"
>> Linux under VirtualBox under SL6x).
>> 
>> I do not know which applications/environments you support in this way.  A
>> list of all that are not subject to for-fee or equivalent non-distributable
>> licenses and for which you are willing to provide the scripts greatly would
>> be appreciated.  Maintaining such environments across new major OS
>> environment releases often entails a large amount of effort.
>> 
>> Yasha
>> 
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