cookiecutter-django/docs/developing-locally-docker.rst

Getting Up and Running Locally With Docker
==========================================

.. index:: Docker

The steps below will get you up and running with a local development environment.
All of these commands assume you are in the root of your generated project.


Prerequisites
-------------

* Docker; if you don't have it yet, follow the `installation instructions`_;
* Docker Compose; refer to the official documentation for the `installation guide`_.

.. _`installation instructions`: https://docs.docker.com/install/#supported-platforms
.. _`installation guide`: https://docs.docker.com/compose/install/


Attention, Windows Users
------------------------

Currently PostgreSQL (``psycopg2`` python package) is not installed inside Docker containers for Windows users, while it is required by the generated Django project. To fix this, add ``psycopg2`` to the list of requirements inside ``requirements/base.txt``::

    # Python-PostgreSQL Database Adapter
    psycopg2==2.6.2

Doing this will prevent the project from being installed in an Windows-only environment (thus without usage of Docker). If you want to use this project without Docker, make sure to remove ``psycopg2`` from the requirements again.


Build the Stack
---------------

This can take a while, especially the first time you run this particular command on your development system::

    $ docker-compose -f local.yml build

Generally, if you want to emulate production environment use ``production.yml`` instead. And this is true for any other actions you might need to perform: whenever a switch is required, just do it!


Run the Stack
-------------

This brings up both Django and PostgreSQL. The first time it is run it might take a while to get started, but subsequent runs will occur quickly.

Open a terminal at the project root and run the following for local development::

    $ docker-compose -f local.yml up

You can also set the environment variable ``COMPOSE_FILE`` pointing to ``local.yml`` like this::

    $ export COMPOSE_FILE=local.yml

And then run::

    $ docker-compose up

To run in a detached (background) mode, just::

    $ docker-compose up -d


Execute Management Commands
---------------------------

As with any shell command that we wish to run in our container, this is done using the ``docker-compose -f local.yml run --rm`` command: ::

    $ docker-compose -f local.yml run --rm django python manage.py migrate
    $ docker-compose -f local.yml run --rm django python manage.py createsuperuser

Here, ``django`` is the target service we are executing the commands against.


(Optionally) Designate your Docker Development Server IP
--------------------------------------------------------

When ``DEBUG`` is set to ``True``, the host is validated against ``['localhost', '127.0.0.1', '[::1]']``. This is adequate when running a ``virtualenv``. For Docker, in the ``config.settings.local``, add your host development server IP to ``INTERNAL_IPS`` or ``ALLOWED_HOSTS`` if the variable exists.


.. _envs:

Configuring the Environment
---------------------------

This is the excerpt from your project's ``local.yml``: ::

  # ...

  postgres:
    build:
      context: .
      dockerfile: ./compose/production/postgres/Dockerfile
    volumes:
      - postgres_data_local:/var/lib/postgresql/data
      - postgres_backup_local:/backups
    env_file:
      - ./.envs/.local/.postgres

  # ...

The most important thing for us here now is ``env_file`` section enlisting ``./.envs/.local/.postgres``. Generally, the stack's behavior is governed by a number of environment variables (`env(s)`, for short) residing in ``envs/``, for instance, this is what we generate for you: ::

    .envs
    ├── .local
    │   ├── .django
    │   └── .postgres
    └── .production
        ├── .caddy
        ├── .django
        └── .postgres

By convention, for any service ``sI`` in environment ``e`` (you know ``someenv`` is an environment when there is a ``someenv.yml`` file in the project root), given ``sI`` requires configuration, a ``.envs/.e/.sI`` `service configuration` file exists.

Consider the aforementioned ``.envs/.local/.postgres``: ::

    # PostgreSQL
    # ------------------------------------------------------------------------------
    POSTGRES_DB=<your project slug>
    POSTGRES_USER=XgOWtQtJecsAbaIyslwGvFvPawftNaqO
    POSTGRES_PASSWORD=jSljDz4whHuwO3aJIgVBrqEml5Ycbghorep4uVJ4xjDYQu0LfuTZdctj7y0YcCLu

The three envs we are presented with here are ``POSTGRES_DB``, ``POSTGRES_USER``, and ``POSTGRES_PASSWORD`` (by the way, their values have also been generated for you). You might have figured out already where these definitions will end up; it's all the same with ``django`` and ``caddy`` service container envs.

One final touch: should you ever need to merge ``.envs/production/*`` in a single ``.env`` run the ``merge_production_dotenvs_in_dotenv.py``: ::

    $ python merge_production_dotenvs_in_dotenv.py

The ``.env`` file will then be created, with all your production envs residing beside each other.


Tips & Tricks
-------------

Activate a Docker Machine
~~~~~~~~~~~~~~~~~~~~~~~~~

This tells our computer that all future commands are specifically for the dev1 machine. Using the ``eval`` command we can switch machines as needed.::

    $ eval "$(docker-machine env dev1)"

Debugging
~~~~~~~~~

ipdb
"""""

If you are using the following within your code to debug: ::

    import ipdb; ipdb.set_trace()

Then you may need to run the following for it to work as desired: ::

    $ docker-compose -f local.yml run --rm --service-ports django


django-debug-toolbar
""""""""""""""""""""

In order for ``django-debug-toolbar`` to work designate your Docker Machine IP with ``INTERNAL_IPS`` in ``local.py``.


Mailhog
~~~~~~~

When developing locally you can go with MailHog_ for email testing provided ``use_mailhog`` was set to ``y`` on setup. To proceed,

#. make sure ``mailhog`` container is up and running;

#. open up ``http://127.0.0.1:8025``.

.. _Mailhog: https://github.com/mailhog/MailHog/