CloudFoundry: each app running at a separate virtual machine?

Question

I printed ENV of a running Rails app.

PATH /home/vcap/app/vendor/bundle/ruby/1.9.1/bin:/home/vcap/app/bin:/bin:/usr/bin
PWD  /home/vcap/app

It is different between different type app.So cloud foundry create a new vm for each app? does it use light weight VM like QEUM?

Answer 1

Kind of... CF creates a warden container for each app located on the DEA. That's why there might be differences (or similarities) between the output of the environmental variables.

Answer 2

Each App in CF run inside a DEA (Droplet execution agent) VM. But within this VM each app run inside of a warden container which is a small sandboxed environment for that app. You can think of warder containers as small VMs inside the DEA VM.

Each container has its own IP/Port internally NAT'ed and thus avoid any port conflict issue when pushing apps that might use same port out of the box on the same DEA VM.