Archive for May 31st, 2009

Keeping Gentoo Fresh

May 31st, 2009 by Sjan Evardsson

I had a converstion with a friend about Linux distros earlier today, and I was asked why I choose to run Gentoo on my web server. He told me that Gentoo was too hard to maintain on a server, and that when it came time to upgrade something (like Apache or PHP) due to security patches that it took too long, and too often failed. I was confused by this so I asked for clarification. What he described was the pain of updating anything on a “stale” Gentoo machine.

Unlike so many of the other popular distros, Gentoo does not, by default, use pre-compiled packages. So unlike doing rpm -i or apt-get install doing emerge on Gentoo requires that the package you are installing, and any missing dependencies, are pulled in as source code and compiled. When you think about adding packages like, say, Lynx, the process takes only a few minutes on a moderately decent machine. (Mine is a PII 966 and Lynx took about 4 minutes start to finish). When you talk about upgrading something like Apache, however, the length of time it takes depends not only on the speed of the machine, but how many of its dependencies are out of date. In fact, if you fail to update regularly you can run into an issue where not only are most of your files out of date, but your system profile is out of date and you need to do some serious wrenching to get the whole thing working again. In the times that this has happened to me (twice) I was able to get the system up-to-date once, and just gave up and reinstalled a newer version the second time. (These were both rarely used VMs, and not production boxes.) However, updating the profile on a “fresh” Gentoo is (in my experience) a painless procedure of rm /etc/make.profile && ln -sf /usr/portage/profiles/profile_name /etc/make.profile && emerge -uND world (uND : update newuse deep: update, take into account new use settings from the profile and make.conf, and include deep dependencies).

So how do I avoid the “stale” Gentoo syndrome? I take a three-step approach.

  1. A daily cron job runs emerge -puvD world (puvD : pretend update verbose deep : just tells you what would be emerged, in an update, verbosely, and include deep dependencies) and emails me the output. This enables me to see each morning which packages have updates available.
  2. Every day that I have the time for it I log into the machine and run emerge -uD world and follow it up with etc-update (if needed) and revdep-rebuild if any libraries were included in the updates. (I save building new kernels for Sundays, and that doesn’t happen all that often, but I do like to always run the latest.)
  3. I check the messages from emerge to see if there are any special configuration changes that need to happen post-install that cannot be handled by etc-update. For instance, changing configurations in /etc/conf.d/packagename, new profiles or anything of that sort.

Ok, so I like to keep my system on the latest and keep a shiny new everything on it. How does that compare with something like, say, Debian? In Debian (and Debian-based distros) you can update packages to a certain point, after which the package for that version of Debian is no longer supported or updated. So you need to upgrade your version, and your kernel, which you do with apt-get upgrade dist. Seems easy enough. And how does Gentoo handle version upgrades? It doesn’t need to. If you keep your system up-to-date in the way I described your system will match whatever the latest Gentoo release has. In fact, I built my web server using Gentoo 2006.0 and have been keeping it up-to-date since then. (Gentoo seems to have stopped doing the biannual releases, btw – they are now releasing updated minimal install CDs nearly weekly for each architecture.)