My Linux container temptation: running other Linuxes

February 25, 2015

We use a very important piece of (commercial) software that is only supported on Ubuntu 10.04 and RHEL/CentOS 6, not anything later (and it definitely doesn't work on Ubuntu 12.04, we've tried that). It's currently on a 10.04 machine but 10.04 is going to go out of support quite soon. The obvious alternative is to build a RHEL 6 machine, except I don't really like RHEL 6 and it would be our sole RHEL 6 host (well, CentOS 6 host, same thing). All of this has led me to a temptation, namely Linux containers. Specifically, using Linux containers to run one Linux as the host operating system (such as Ubuntu 14.04) while providing a different Linux to this software.

(In theory Linux containers are sort of overkill and you could do most or all of what we need in a chroot install of CentOS 6. In practice it's probably easier and surer to set up an actual container.)

Note that I specifically don't want something like Docker, because the Docker model of application containers doesn't fit how the software natively works; it expects an environment with cron and multiple processes and persistent log files it writes locally and so on and so forth. I just want to provide the program with the CentOS 6 environment it needs to not crash without having to install or actually administer a CentOS 6 machine more than a tiny bit.

Ubuntu 14.04 has explicit support for LXC with documentation and appears to support CentOS containers, so that's the obvious way to go for this. It's certainly a tempting idea; I could play with some interesting new technology while getting out of dealing with a Linux that I don't like.

On the other hand, is it a good idea? This is certainly a lot of work to go to in order to avoid most of running a CentOS 6 machine (I think we'd still need to watch for eg CentOS glibc security updates and apply them). Unless we make more use of containers later, it would also leave us with a unique and peculiar one-off system that'll require special steps to administer. And virtualization has failed here before.

(I'd feel more enthused about this if I thought we had additional good uses for containers, but I don't see any other ones right now.)

Written on 25 February 2015.
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Last modified: Wed Feb 25 01:39:40 2015
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