I was working at a place a few years ago where I had to move a whole bunch of applications, running on Ubuntu Hardy circa 2008, to new servers (well VMs), as the servers were being decommissioned. A lot of the applications were running on Ruby 1.8 which newer versions of Ubuntu don't provide packages for, and it's not very easy to compile it yourself due to dependencies on old versions of OpenSSL. We upgraded some applications to newer versions of Ruby, however some weren't worth the effort or risk (before Ruby 2, even a patch level change likely had breaking changes).
Although other systems were running Ubuntu, we decided to go with CentOS 6 for these systems - mainly because it was preferred by the current era of sysadmins. It also had packages for Ruby 1.8 or at least the correct dependencies (I can't remember exactly). And even better, although it was released in 2011, it is still supported until 2020.
If I was going to do the same today I'd just use Docker, but it was fairly new back then.
Although other systems were running Ubuntu, we decided to go with CentOS 6 for these systems - mainly because it was preferred by the current era of sysadmins. It also had packages for Ruby 1.8 or at least the correct dependencies (I can't remember exactly). And even better, although it was released in 2011, it is still supported until 2020.
If I was going to do the same today I'd just use Docker, but it was fairly new back then.