This repo contains the Dockerfile used to build the Datadog Agent (https://github.com/DataDog/dd-agent).
The Datadog Agent is built using a Chef omnibus project (https://github.com/DataDog/dd-agent-omnibus) on CircleCi.
The base image of the container is a homemade i386 image of Centos 5.
You'll need:
VirtualBox (Last tested on 4.3.x)
Vagrant (Last tested on 1.7)
Then you can clone the repo and run:
vagrant up