####################
Blogging with Docker
####################

One issue with :doc:`the previous approach to blogging
</blog/2013/01/14/blogging-with-restructuredtext-a-google-domain-and-sphinx>` is
the requirement of installing packages to build the blog.
:doc:`Virtual machines </blog/2013/01/01/linux-mint-installation>` can be
installed to alleviate this matter, but at the cost of manually installing an OS
and the corresponding packages.  Furthermore, the virtual machine needs its own
hacks and a lot of computational resources to work properly.

`Docker CE`_ is the latest solution to this problem.  `Installing it`_ is very
simple and you only need to run

.. code:: bash

    sudo usermod -aG docker ${USER}

.. _Docker CE: https://github.com/docker/docker-ce
.. _Installing it: https://docs.docker.com/install/linux/docker-ce/ubuntu/#install-docker-ce-1

afterwards if you would like to use Docker as a non-root user.  Make sure to
reboot to apply the new permissions.

Docker itself only needs a :file:`Dockerfile`, but this post will include
additional items in order to replace the older blogging methods:

.. include:: Dockerfile
   :code: docker

The :file:`requirements.txt` is to support
:doc:`data analysis </blog/2013/01/04/set-up-data-analysis-environment>`:

.. include:: requirements.txt
   :code: text

The files :file:`.gitconfig`

.. include:: gitconfig
   :code: text

and :file:`.inputrc`

.. include:: inputrc
   :code: text

and :file:`.vimrc`

.. include:: vimrc
   :code: text

are more for convenience.

Copy Data Between Docker Volume and Host
========================================

Suppose you have a volume created by

.. code:: bash

   docker volume create blog_data

Any data transfer between host and docker volumes must happen via a container.
As an example, suppose we need to generate an SSH key to connect to
`BitBucket`_:

.. code:: bash

    mkdir .ssh
    cd .ssh
    ssh-keygen -f id_rsa
    docker container create --name dummy --mount source=blog_data,target=/workspace/data python:3-slim
    cd ..
    docker cp .ssh dummy:/workspace/data/.ssh
    docker rm dummy

.. _BitBucket: https://confluence.atlassian.com/bitbucket/set-up-an-ssh-key-728138079.html#SetupanSSHkey-ssh2

Running a Docker Container
==========================

Suppose the blog uses the provided :download:`Dockerfile <Dockerfile>` to build an image as
follows:

.. code:: bash

    docker build -t blogger .

The blog needs three processes to fully operate:

.. include:: run_containers.sh
   :code: bash

- *sphinx_autobuild* is responsible for looking at the blog data for changes and
  rebuilding the site.

  - Before running the related commands, you should clone the repository.

    .. code:: bash

       eval `ssh-agent`
       hg clone ssh://hg@bitbucket.org/alphaXomega/allthingsphi

- *python_server* tests the blog with a local web server.  Remember that this process
  will push data to Google Cloud, make sure to initialize it.

    .. code:: bash

       gcloud init

- *jupyter_notebook* allows editing of blog content.  It must use the following
  settings in order to run inside a container.

    .. code:: bash

          jupyter notebook --allow-root --ip=0.0.0.0 --no-browser