Use NixOS configurations to provision Docker containers.

Read about the what and why in this blog post

The easy way to do this is to use Vagrant.

When you have Vagrant installed:

git clone https://github.com/zefhemel/nix-docker.git
cd nix-docker
vagrant up
vagrant ssh

If all went well, you're now in a VM that has both Docker and Nix installed and nix-docker in its path.

At this point you need to connect to the VM and have nix setup the vagrant users own custom package stores. execute the follow

nix-channel --update
nix-env -i hello

You can now cd into the nix-docker/samples directory to try to build some of the examples. Note that the ~/nix-docker directory is mounted from your host machine, so you can edit your files with your favorite editor and have them available within the VM.

To use nix-docker you need Nix installed as well as Docker. Realistically, your best way to do this on an Ubuntu (12.04 or 13.04) box. Once these are installed, installing nix-docker is as simple as:

git clone https://github.com/zefhemel/nix-docker.git
nix-env -f nix-docker/default.nix -i nix-docker

To build a stand-alone Docker image:

nix-docker -b -t my-image configuration.nix

This will build the configuration specified in configuration.nix, have a look in the samples/ directory for examples. It will produce a docker image named my-image which you can then run anywhere. Use username/my-image to be able to push them to the Docker index.

To build a host-mounted package:

nix-docker -t my-image configuration.nix

This will produce a Nix package (symlinked in the current directory in result) containing a script you can use to spawn the container using Docker, e.g.:

sudo -E ./result/sbin/docker-run

to run the container in the foreground, or:

sudo -E ./result/sbin/docker-run -d

to daemonize it. What the docker-run script will do is check if there's already a docker image available with the current image name and tag based on the Nix build hash. If not, it will quickly build it first (these images take up barely any space on disk). Then, it will boot up the container.

Distributing host-mounted packages is done by first copying the Nix closure resulting from the build to the target machine (when you do the build it will give you example commands to run):

nix-copy-closure root@targetmachine /nix/store/....

Then, you can spawn the container remotely with the script path provided in the output of the build command.