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How to build and publish base boxes for Docker?

If you don't know about it yet, go check out Docker, which makes manipulating LXC containers painless.

Docker comes with a registry where you can find images to use for your containers. You can also create and upload your own images in this repository, which is the subject of this article.

Create an account on the Docker index website: https://index.docker.io.

On your box, login:

    $> docker login
    Username (): crohr
    Password: 
    Email (): hi@example.com
    Login Succeeded

For debian-based boxes, just use the mkimage-debian.sh script in contrib/:

    $> ./mkimage-debian.sh crohr/ubuntu lucid http://archive.ubuntu.com/ubuntu
    ...
    + img=f7e10b978e8c
    + docker tag f7e10b978e8c crohr/ubuntu lucid
    + '[' lucid = wheezy ']'
    + docker run -i -t crohr/ubuntu:lucid echo success
    success
    + '[' lucid '!=' sid -a lucid '!=' unstable ']'
    ++ docker run crohr/ubuntu:lucid cat /etc/debian_version
    + ver=squeeze/sid
    + docker tag f7e10b978e8c crohr/ubuntu squeeze/sid
    2013/05/24 17:05:40 error: Illegal tag name: squeeze/sid

Note: The second tag is not created, but it does not matter (?).

Then, check that your image is indeed created:

    $> docker images
    REPOSITORY          TAG                 ID                  CREATED
    crohr/ubuntu        lucid               f7e10b978e8c        34 minutes ago
    ubuntu              latest              8dbd9e392a96        6 weeks ago
    ubuntu              12.10               b750fe79269d        8 weeks ago
    ubuntu              12.04               8dbd9e392a96        6 weeks ago
    ubuntu              quantal             b750fe79269d        8 weeks ago
    ubuntu              precise             8dbd9e392a96        6 weeks ago

Now push it to the central repository:

    $> docker push crohr/ubuntu
    The push refers to a repository [crohr/ubuntu] (len: 1)
    Processing checksums
    Sending image list
    Pushing repository crohr/ubuntu to registry-1.docker.io (1 tags)
    Pushing f7e10b978e8c15bde845374c490862befb181f0943a0ae2076d070573a435b16
    145858560/145858560 (100%)
    Pushing tags for rev [f7e10b978e8c15bde845374c490862befb181f0943a0ae2076d070573a435b16] on {registry-1.docker.io/users/crohr/ubuntu/lucid}

That's it! Now other people can pull your images using docker pull crohr/ubuntu.