In the previous post I covered how to run [Docker inside LXD][1] which is a good way to get access to the portfolio of application provided by Docker while running in the safety of the LXD environment.
One use case I mentioned was offering a LXD container to your users and then have them use their container to run Docker. Well, what if they themselves want to run other Linux distributions inside their container using LXD, or even allow another group of people to have access to a Linux system by running a container for them?
Turns out, LXD makes it very simple to allow your users to run nested containers.
### Nesting LXD
The most simple case can be shown by using an Ubuntu 16.04 image. Ubuntu 16.04 cloud images come with LXD pre-installed. The daemon itself isn’t running as it’s socket-activated so it doesn’t use any resources until you actually talk to it.
So lets start an Ubuntu 16.04 container with nesting enabled:
As this post is pretty short, I figured I would spend a bit of time to talk about the [demo server][2] we’re running. We also just reached the 10000 sessions mark earlier today!
That server is basically just a normal LXD running inside a pretty beefy virtual machine with a tiny daemon implementing the REST API used by our website.
When you accept the terms of service, a new LXD container is created for you with security.nesting enabled as we saw above. You are then attached to that container as you would when using “lxc exec” except that we’re doing it using websockets and javascript.
The containers you then create inside this environment are all nested LXD containers.
You can then nest even further in there if you want to.
We are using the whole range of [LXD resource limitations][3] to prevent one user’s actions from impacting the others and pretty closely monitor the server for any sign of abuse.
If you want to run your own similar server, you can grab the code for our website and the daemon with:
