From time to time, Firefox developers encounter errors which only appear on our build machines. Meaning -- after they've likely already failed numerous times to coax the failure form their own environment -- they must resort to requesting RelEng to pluck a system from our infrastructure so they can use it for debugging: we call this a slave loan, and they happen frequently.

Case in point: bug #689291

Firefox is a huge open source project: slave loans can never scale enough to serve our community. So, this weekend I took a whack at solving this problem with Docker. So far, five [of an eventual fourteen] containers have been published, which replicate the following aspects of our in house build environments:

• OS (Centos 6)
• libraries (yum is pointed at our in house repo)
• compilers/interpreters/utilities (installed to /tools)
• ENV variables

As usual, you can find my scratch work on GitHub: mozilla/build-environments




What Are These Environments Based On?

For a long time, builds have taken place inside of chroots built with Mock. We have three bare bones mock configs which I used to bake some base platform images:

mozilla-centos6-x86_64-android
mozilla-centos6-x86_64
mozilla-centos6-i836

On top of our Mock configs, we further specialize build chroots via build scripts powered by Mozharness. The specifications of each environment are laid out in these mozharness configs. To make use of these, I wrote a simple script which converts a mozharness config into a Dockerfile.

The environments I've published so far:

releng_base_linux_64
releng_base_linux_32

The next step, before I publish more containers, will be to write some documentation for developers so they can begin using them for builds with minimal hassle. Stay tuned!

http://linux-poetry.com/blog/section/mozilla/17/