boot2docker

boot2docker is a lightweight Linux distribution based on Tiny Core Linux made specifically to run Docker containers. It runs completely from RAM, weighs ~23MB and boots in ~5-6s (YMMV).

Download

Head over to the Releases Page to grab the ISO.

To 'install' the ISO onto an SD card, USB-Stick or even empty hard disk, you can use dd if=boot2docker.iso of=/dev/sdX. This will create the small boot partition, and install an MBR.

How to use

Simply boot from the ISO, and you're done. It runs on VMs and bare-metal machines.

If you want your containers to persist across reboots, just attach an ext4 formatted disk to your VM, and boot2docker will automount it on /var/lib/docker. It will also persist the SSH keys of the machine.

boot2docker auto logs in, but if you want to SSH into the machine, the credentials are:

    login: docker
    pass: tcuser

Make sure to setup a port forward from host to guest port 22. Avoid bridged networking due to the static login and password.

Demo

http://www.youtube.com/watch?v=QzfddDvNVv0

Features

• Kernel 3.12.1 with AUFS
• Docker 0.7
• LXC 1.0-alpha2
• Container persistence via disk automount on /var/lib/docker
• SSH keys persistence via disk automount

How to build

boot2docker is built with Docker, via Dockerfiles.

It is composed in three distinct steps:

• base: fetches, patches with AUFS support and builds the 3.12.1 Linux Kernel with Tiny Core base configuration
• rootfs: builds the base rootfs for boot2docker (not complete)
• running rootfs: when you run this image, it will build the rootfs, download the latest Docker release and create the .iso file on / of the container. This way you can update Docker without having to completely rebuild everything.

So the build process goes like this:

    # $ sudo docker build -t steeve/boot2docker-base base/
    # OR for most uses, avoid re-building and downloading lots of ubuntu packages by:
    $ sudo docker pull steeve/boot2docker-base
    $ sudo docker build -t boot2docker rootfs/

Once that's done, to build a custom boot2docker.iso, just run the built rootfs image:

    $ sudo docker rm build-boot2docker
    $ sudo docker run --privileged -name build-boot2docker boot2docker
    $ sudo docker cp build-boot2docker:/boot2docker.iso .

Now you can install the iso to a USB drive, SD card, CD-Rom or hard-disk. The image contains a Master Boot Record, and a partition table, so can be written to a raw device.

    sudo dd if=boot2docker.iso of=/dev/sdX

FAQ

Login as root

Run sudo -s as the docker user.

Why not CoreOS?

I got asked that question a lot, so I thought I should put it here once and for all. CoreOS is targeted at building infrastructure and distributed systems. I just wanted the fastest way to boot to Docker.