[CentOS-devel] SCL

Tue Jul 22 15:21:49 UTC 2014
Pat Riehecky <riehecky at fnal.gov>

On 07/21/2014 03:27 PM, Peter Meier wrote:
> SCLs are really something of the most innovative things that came out
> within the EL-ecosystem in the past few years and which has the
> potential to make the platform really more interesting for developers
> and others that have "more modern" requirements than the latest major EL
> release.

I'll also toss a quick plug in for my personal favourite use of SCLs - 
legacy software.

The ability to add more modern software in parallel is nice, but I often 
find I've got a lot of legacy code that needs to hang around for longer 
than I'd like.  Shoving this older (often well past EOL) software in a 
corner where I don't have to touch it is strangely comforting.

"Oh, your application requires this strange bug from OpenLDAP 2.1, ok 
I'll put that over here listening on localhost and you can deal with 
making your stuff talk to it"
"You mean your software doesn't work with MySQL 5.1, ok here is a 5.0 
server listening on localhost you can use"
Then simply add stunnel with client validation and you're all set.

There is a lot more upfront work, but migrating legacy apps has always 
been a real pain for me.  I see the SCL technology as perhaps the 
greatest step forward on this front in a long time.  This weird app 
requires these packages, fine here is a self-contained environment with 
all your stuff and I'll never touch it while fixing other issues.  
Docker may also be a benefit for this use case as well, but SCLs don't 
make "one more thing to manage".


Pat Riehecky

Scientific Linux developer