It's not mentionned in the article so I don't see how they handled security? Espcially network wise, how do they prevent spamming?
print(open('/proc/cpuinfo').read())
Seems to have network access... I git cloned a small repo from git hub. It already has gcc installed. Looks like they should lock it down a bit more.
The 24 core Xeons are our (rackspace) OnMetal high memory boxes, you don't actually have 24 cores, docker just pulled that from the host, each container is limited.