I’ve touched on it a couple times, and it’s related to why I love things like Homebrew, but I like package installers. While I can, and have many times, installed and packaged from source, it scares me and I don’t like it. When I talked about Homebrew, I mentioned in passing that I use yum to manage packages on my servers, and someone asked me “What’s that?”
When I started this blog in 2009, the very first post was about understanding how to mess with my VPS and tweak it to work well with WordPress and everything else. In the five years since, I’ve learned a great deal about servers, tweaks, how to break things, but also how to upgrade them smartly. I’ve had struggles with SVN and GIT, but I understand that managing versions and revisions is a sane way to handle upgrades. But at the same time, not compiling code means I have more free time to mess with the stuff I like.
This brings us to Yum.
Yum is a software package manager manager, which means it checks various RPM Package Managers, sees if there is software you have that has an update, and updates it. An RPM Package Manager (or an RPM, yes, it’s a recursive acronym, just like PHP) stores packaged versions of code… I have a feeling someone’s looking at me like I spoke a new language.
Let’s step back further. Your server is a computer and runs software. Most people have the experience of installing software via packaged installers (I used to make them for a living). When you download an app onto your phone, the phone downloads the package and runs the installer. This is similar to WordPress, right? You download the zip, unpack it, and run an installer. But your server, well, for a very long time people didn’t have installer packages, they had source code. The source code was downloaded, unzipped (hush, you know what I mean), compiled, and then installed.
Yes, compiling code takes a long time. That joke is less funny than it is accurate to some of us. It’s not something most of us do any more, though, because code now tends to come pre-compiled, and that’s where package managers come into play. You see, someone realized that they could pre-compile code for all servers. It’s not the same code for all the servers, though, because there are so many flavors of servers, it’s mind boggling.
But that said, if you know your flavor of server, you can use an RPM that matches to install software. So the RPM is like a massive server that has all the available installs for your server. When you add in yum, which installs the packages, you can then enter a world of automation where every night your server checks for new packages and installs them!
Yum has a meaning. “Yellowdog Updater, Modified.” I didn’t say it was a good meaning. Yum has a bunch of obvious commands like “yum install NAME” and “yum update” which you can use to install extra add-ons like Memcached and so on. There are also yum utilities (yum-utils, which let you further customize automation by scripting commands.
Just to touch on one at random, today I got an email from my server saying that it had run /usr/bin/yum -c /etc/yum.conf -y update for me. This is normal, I configured it to do that at midnight every day.
There are unfinished transactions remaining. You might consider running yum-complete-transaction first to finish them.
Now it did run the rest of the installs, so I did what any smart person does. I went and looked up this new command, only to find a string of bug reports from 2007-2009. It’s 2014, so I went and ran it once. It cleaned up one package and said I had another 244 left. Interesting. I ran it again. 243. I saw my day flash before my eyes and then decided to run the safer version:
yum-complete-transaction --cleanup-only
Safer and faster. Everything was cleaned, and update runs great now.
Is there a risk with this automation? Of course! Which is why I take a backup every night, right before the update happens. I’m not crazy after all.
Comments
2 responses to “Yum!”
Mika … you mean at the end, “I may be crazy, but I’m not an idiot,”.
@woody: That’s up for debate, Dad.