[GoLugTech] Multiple versions and Red Hat Software Collections --

[Bryan J Smith]

Umm ... Python, Java and other p-type software is different than
system-level, or even back-end desktop. That was the promise of
"write once, run everywhere." But even things like Python and Java
_do_ run into versioning differences, let alone library ones.

This has been a major issue on RHEL.

Because RHEL is updated for 10 years (+3 optional extended), a lot of
customers run into the case of new software being developed for newer
languages, which doesn't work on older languages ... all while
vice-versa happens too. This includes even different versions of
Python 2 itself (ignoring Python 2), web databases, web servers and
modules, etc...

After many years of many customers asking for something, so they can
run stable Enterprise Linux versions, but update and even run
concurrent versions of different compilers, p-type languages,
databases, services, modules, etc... Red Hat introduced Software
Collections (RHSCL aka "SCL" on CentOS). The alternative, newer
versions are maintained for 2.5-5 years, typically 3 years, which is a
good duration as software written for new versions are typically
updated every 2-3 years. And at 3 years, that's 2-3x longer than most
"leading edge" distros. [1]

The releases are still packaged, but install in /opt with various
tools to change the environment, rather transparently. [2]

Probably the second most common use is when customers want to run the
exact same version on two RHEL versions that are 3-4 years apart. Say
they have old RHEL6 on 5+ year old systems, while they also are
deploying new RHEL7 software on new systems.

When you're doing C, and trying to maintain API -- let alone ABI
(binary) -- compatibility for 10+ years -- in a single distro release
-- it's a whole different ballgame.
...
Writing to a p-type, portable language with its own byte code run-time
is not the same.

-- bjs

[1] https://access.redhat.com/support/policy/updates/rhscl

[2] https://access.redhat.com/documentation/en-US/Red_Hat_Developer_Toolset/1/html-single/Software_Collections_Guide/index.html#sect-Enabling_the_Software_Collection