Docker connection plugin for Ansible

This repo contains a connection plugin for Ansible that lets you configure Docker containers without needing to install an SSH server or Ansible itself into the container.

This is a work-in-progress.

Requires Docker 1.3.1. On Linux, you could probably get away with 1.3.0, but On OS X, you'll need Docker 1.3.1 and boot2docker 1.3.1.

Known limitations

• can't explicitly configure docker connection parameters
• when using boot2docker, TLS must be disabled (see boot2docker issues)
• sudo isn't supported
• su isn't supported

How to install

1. Create a connection_plugins directory next to your playbooks.
2. Copy the connection_plugins/docker.py file to the directory.

ansible.cfg (remote temp)

You may also need to modify the remote temporary directory (I had to do this with the ubuntu base image). Add the following to your ansible.cfg:

[defaults]
remote_tmp = /tmp

boot2docker issues

Because of a docker issue, if you are using boot2docker, you must disable TLS or the connection plugin will hang.

To disable TLS in boot2docker:

boot2docker ssh
sudo -i
/etc/init.d/docker stop
echo DOCKER_TLS="no" > /var/lib/boot2docker/profile
/etc/init.d/docker start

Your DOCKER_HOST should now point to port 2376 (the IP may not match the one below), and the DOCKER_TLS_VERIFY and DOCKER_CERT_PATH environment variables should not be deifned.

export DOCKER_HOST=tcp://192.168.59.103:2375
unset DOCKER_TLS_VERIFY
unset DOCKER_CERT_PATH

How to use it

In your plays, add connection: docker. For example:

- name: configure my container
  connection: docker
  hosts: webcontainer

  tasks:
    - ...

You need a running container first, and you'll need to add the hostname to Ansible's inventory. One way to do it is to write an initial play that runs a container using the docker module and then uses the add_host module to add to the inventory, like this:

- name: start up a docker container
  hosts: localhost
  vars:
    base_image: ubuntu
    docker_hostname: webcontainer

  tasks:
    - name: start up a docker container by running bash
      local_action: docker image={{ base_image }} name={{ docker_hostname }} detach=yes tty=yes command=bash
    - name: add the host
      add_host: name={{ docker_hostname }}

- name: configure the web container
  hosts: webcontainer
  connection: docker
  tasks:
   - ...

Example: ipython notebook

Check out the ipython.yml playbook for an example that builds a container that runs an IPython notebook.

To build the example image, just do:

ansible-playbook ipython.yml

It will build a docker image called lorin/ipython

Start the IPython notebook

This will start the notebook and mount /notebooks to your current directory on the host.

docker run -d -p 8888:8888 -v `pwd`:/notebooks lorin/ipython

Access the notebook

If you're running docker locally on Linux, browse to http://localhost:8888.

If you're using boot2docker, browse to the IP address associated with the DOCKER_HOST environment variable, e.g.: http://192.168.59.104:8888

FAQ

Q: Does it work with boot2docker?

A: It does, but you need to disable TLS. See above.

Q: What's with the pre_image and final_image in the ipython.yml playbook?

A: The playbook creates the pre-image by starting a container from a base ubuntu image, configuring it with ansible, and then committing it. The playbook creates the final image from the pre-image using a Dockerfile to set things like the working directory, exposed ports, and command to run.

If you know how to do this one step, please let me know.

Q: Why does this repo contain custom docker and docker_image modules?

A: The upstream modules don't have support for boot2docker yet. I've submitted a pull request to get these added.