alex.polvi.net

You might not know what it is… but you still should use this blog button. All great paths have their foot prints in snow.

5/25 @ 5:25

snow in the quad.

I thought it would be interesting to explain the lifetime of a Firefox update. In this post we will explore from the point at which the build is finished, the mirrors are all staged, and the update is finally dropped into place.

The Web Developer

At the heart of a Firefox is the Automatic Update Service (AUS). AUS was written by Mike Morgan. Firefox will periodically (roughly once a day) check AUS for updates. Most of the time nothing is returned, just a blank XML file signifying that there are no updates. However, on special days, such as release days, the XML file returns a valid update.

The update.xml will contain a URL to download.mozilla.org (DMO). DMO is powered by a tool called bouncer, which was also written by Mike Morgan (along with Lars Lohn and Scott Kveton). Bouncer does random, weighted, mirror distribution for our downloads. We give the mirrors with more bandwidth more weight and then they get more traffic. This way we can accommodate mirrors of any capacity.

The Mirror Admin

For some reason these guys have bandwidth to burn, and love doing it.

The mirrors are our only method of distribution, and their contributions are vital for Firefox’s existence.

The Infrastructure

AUS and bouncer are hosted at the Open Source Lab, here at Oregon State University.

AUS is load balanced across about 10 servers. We could host it on one if we wanted to, but why not be safe?

The community

I used to think it was the best thing ever when I saw people around campus wearing Firefox shirts (people I didn’t even know!)… but now I get the most joy when I hear people, like tenant Emily, saying they just got a Firefox update. This is because it can be reduced down to something that is provided by a close group of friends (and co-workers).

Many people don’t realize that every Firefox update on the planet goes through software that was written by Mike Morgan, servers that are hosted at Oregon State University, and mirrors that are kept by the most generous sysadmins you’ll ever find.

Surely there are many more people that make this happen, but it’s still rewarding to know that we play a vital part in something so huge.