[mikko-apo]

We used Docker for the Hello World Open coding competition.

We provided CI for the 2500 teams and also ran the competition using Docker (both on top of AWS EC2 instances). I think that without Docker the implementation would have been a lot more painful and almost impossible given the time constraints we had for the project.

Fast starting and fast shutdown of build and test processes allowed us to run CI builds efficiently on a fairly small amount of nodes. This saved us money and also helped to keep the infrastructure manageable.

Also the additional level of security was really nice since we were running possibly malicious code from 2500 sources. The malicious part became even more evident when Kevin Mitnick tweeted that he might participate: https://twitter.com/kevinmitnick/status/446359450614378496

The Docker image repository was also really handy when we ran the races. We needed build the bots only once and then we could just use the prebuilt images on on race nodes.

Building the actual base image was fairly painful. We support about 20 different programming languages and also package in quite a few libraries. Once the base image build was fully automatized and we had the Docker related processes fully working, it was almost a revelation on how Docker could improve things over the classical virtual machine approach. I can't wait to try it out on another project :)

By the way, the competition finals are today (Tuesday) and streamed live @ https://helloworldopen.com/ (in English and Finnish)

[wpietri]

That sounds really interesting. Please document it! I'd be especially interested to read about the revelations.