.. _development:

Open edX development
====================

In addition to running Open edX in production, Tutor can be used for local development of Open edX. This means that it is possible to hack on Open edX without setting up a Virtual Machine. Essentially, this replaces the devstack provided by edX.

The following commands assume you have previously launched a :ref:`local <local>` Open edX platform. If you have not done so already, you should run::

    tutor local quickstart

In order to run the platform in development mode, you **must** answer no ("n") to the question "Are you configuring a production platform".

Note that the local.overhang.io `domain <https://dnschecker.org/#A/local.overhang.io>`__ and its `subdomains <https://dnschecker.org/#CNAME/studio.local.overhang.io>`__ all point to 127.0.0.1. This is just a domain name that was setup to conveniently access a locally running Open edX platform.

Once the local platform has been configured, you should stop it so that it does not interfere with the development environment::

    tutor local stop

Finally, you should build the ``openedx-dev`` docker image::

    tutor images build openedx-dev

This ``openedx-dev`` development image differs from the ``openedx`` production image:

- The user that runs inside the container has the same UID as the user on the host, in order to avoid permission problems inside mounted volumes (and in particular in the edx-platform repository).
- Additional python and system requirements are installed for convenient debugging: `ipython <https://ipython.org/>`__, `ipdb <https://pypi.org/project/ipdb/>`__, vim, telnet.
- The edx-platform `development requirements <https://github.com/edx/edx-platform/blob/open-release/koa.master/requirements/edx/development.in>`__ are installed.

Since the ``openedx-dev`` is based upon the ``openedx`` docker image, it should be re-built every time the ``openedx`` docker image is modified.

Run a local development webserver
---------------------------------

::

    tutor dev runserver lms # Access the lms at http://local.overhang.io:8000
    tutor dev runserver cms # Access the cms at http://studio.local.overhang.io:8001

Running arbitrary commands
--------------------------

To run any command inside one of the containers, run ``tutor dev run [OPTIONS] SERVICE [COMMAND] [ARGS]...``. For instance, to open a bash shell in the LMS or CMS containers::

    tutor dev run lms bash
    tutor dev run cms bash

To open a python shell in the LMS or CMS, run::

    tutor dev run lms ./manage.py lms shell
    tutor dev run cms ./manage.py cms shell

You can then import edx-platform and django modules and execute python code.

To collect assets, you can use the ``openedx-assets`` command that ships with Tutor::

    tutor dev run lms openedx-assets build --env=dev

.. _bind_mounts:

Bind-mount container directories
--------------------------------

It may sometimes be convenient to mount container directories on the host, for instance: for editing and debugging. Tutor provides different solutions to this problem.

Bind-mount from the "volumes/" directory
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Tutor makes it easy to create a bind-mount from an existing container. First, copy the contents of a container directory with the ``bindmount`` command. For instance, to copy the virtual environment of the "lms" container::

    tutor dev bindmount lms /openedx/venv

This command recursively copies the contents of the ``/opendedx/venv`` directory to ``$(tutor config printroot)/volumes/venv``. The code of any Python dependency can then be edited -- for instance, you can then add a ``import ipdb; ipdb.set_trace()`` statement for step-by-step debugging, or implement a custom feature.

Then, bind-mount the directory back in the container with the ``--volume`` option::

		tutor dev runserver --volume=/openedx/venv lms

Notice how the ``--volume=/openedx/venv`` option differs from `Docker syntax <https://docs.docker.com/storage/volumes/#choose-the--v-or---mount-flag>`__? Tutor recognizes this syntax and automatically converts this option to ``--volume=/path/to/tutor/root/volumes/venv:/openedx/venv``, which is recognized by Docker.

.. note::
    The ``bindmount`` command and the ``--volume=/...`` option syntax are available both for the ``tutor local`` and ``tutor dev`` commands.

Manual bind-mount to any directory
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The above solution may not work for you if you already have an existing directory, outside of the "volumes/" directory, which you would like mounted in one of your containers. For instance, you may want to mount your copy of the `edx-platform <https://github.com/edx/edx-platform/>`__ repository. In such cases, you can simply use the ``-v/--volume`` `Docker option <https://docs.docker.com/storage/volumes/#choose-the--v-or---mount-flag>`__::

    tutor dev run --volume=/path/to/edx-platform:/openedx/edx-platform lms bash

Override docker-compose volumes
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The above solutions require that you explicitly pass the ``-v/--volume`` to every ``run`` or ``runserver`` command, which may be inconvenient. Also, these solutions are not compatible with the ``start`` command. To address these issues, you can create a ``docker-compose.override.yml`` file that will specify custom volumes to be used with all ``dev`` commands::

    vim "$(tutor config printroot)/env/dev/docker-compose.override.yml"

You are then free to bind-mount any directory to any container. For instance, to mount your own edx-platform fork::

    version: "3.7"
    services:
      lms:
        volumes:
          - /path/to/edx-platform/:/openedx/edx-platform
      cms:
        volumes:
          - /path/to/edx-platform/:/openedx/edx-platform
      lms-worker:
        volumes:
          - /path/to/edx-platform/:/openedx/edx-platform
      cms-worker:
        volumes:
          - /path/to/edx-platform/:/openedx/edx-platform

This override file will be loaded when running any ``tutor dev ..`` command. The edx-platform repo mounted at the specified path will be automatically mounted inside all LMS and CMS containers. With this file, you should no longer specify the ``-v/--volume`` option from the command line with the ``run`` or ``runserver`` commands.

.. note::
    The ``tutor local`` commands loads the ``docker-compose.override.yml`` file from the ``$(tutor config printroot)/env/local/docker-compose.override.yml`` directory.

Point to a local edx-platform
-----------------------------

Following the instructions :ref:`above <bind_mounts>` on how to bind-mount directories from the host above, you may mount your own `edx-platform <https://github.com/edx/edx-platform/>`__ fork in your containers by running either::

    # Mount from the volumes/ directory
    tutor dev bindmount lms /openedx/edx-platform
    tutor dev runserver --volume=/openedx/edx-platform lms

    # Mount from an arbitrary directory
    tutor dev runserver --volume=/path/to/edx-platform:/openedx/edx-platform lms

    # Add your own volumes to $(tutor config printroot)/env/dev/docker-compose.override.yml
    tutor dev runserver lms

Prepare the edx-platform repo
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

If you choose any but the first solution above, you will have to make sure that your fork works with Tutor.

First of all, you should make sure that you are working off the ``open-release/koa.3`` tag. See the :ref:`fork edx-platform section <edx_platform_fork>` for more information.

Then, you should run the following commands::

    # Run bash in the lms container
    tutor dev run [--volume=...] lms bash

    # Compile local python requirements
    pip install --requirement requirements/edx/development.txt

    # Install nodejs packages in node_modules/
    npm install

    # Rebuild static assets
    openedx-assets build --env=dev


Debug edx-platform
~~~~~~~~~~~~~~~~~~

To debug a local edx-platform repository, add a ``import ipdb; ipdb.set_trace()`` breakpoint anywhere in your code and run::

    tutor dev runserver [--volume=...] lms

XBlock and edx-platform plugin development
------------------------------------------

In some cases you will have to develop features for packages that are pip-installed next to edx-platform. This is quite easy with Tutor. Just add your packages to the ``$(tutor config printroot)/env/build/openedx/requirements/private.txt`` file. To avoid re-building the openedx Docker image at every change, you should add your package in editable mode. For instance::

    echo "-e ./mypackage" >> "$(tutor config printroot)/env/build/openedx/requirements/private.txt"

The ``requirements`` folder should have the following content::

    env/build/openedx/requirements/
        private.txt
        mypackage/
            setup.py
            ...

You will have to re-build the openedx Docker image once::

    tutor images build openedx

You should then run the development server as usual, with ``runserver``. Every change made to the ``mypackage`` folder will be picked up and the development server will be automatically reloaded.

.. _theming:

Customised themes
-----------------

With Tutor, it's pretty easy to develop your own themes. Start by placing your files inside the ``env/build/openedx/themes`` directory. For instance, you could start from the ``edx.org`` theme present inside the ``edx-platform`` repository::

    cp -r /path/to/edx-platform/themes/edx.org "$(tutor config printroot)/env/build/openedx/themes/"

.. warning::
    You should not create a soft link here. If you do, it will trigger a ``Theme not found in any of the themes dirs`` error. This is because soft links are not properly resolved from inside docker containers.

Then, run a local webserver::

    tutor dev runserver lms

The LMS can then be accessed at http://local.overhang.io:8000. You will then have to :ref:`enable that theme <settheme>` for the development domain names::

    tutor dev settheme mythemename local.overhang.io:8000 studio.local.overhang.io:8001

Re-build development docker image (and compile assets)::

    tutor images build openedx-dev

Watch the themes folders for changes (in a different terminal)::

    tutor dev run watchthemes

Make changes to some of the files inside the theme directory: the theme assets should be automatically recompiled and visible at http://local.overhang.io:8000.

Custom edx-platform settings
----------------------------

By default, tutor settings files are mounted inside the docker images at ``/openedx/edx-platform/lms/envs/tutor/`` and ``/openedx/edx-platform/cms/envs/tutor/``. In the various ``dev`` commands, the default ``edx-platform`` settings module is set to ``tutor.development`` and you don't have to do anything to set up these settings.

If, for some reason, you want to use different settings, you will need to define the ``TUTOR_EDX_PLATFORM_SETTINGS`` environment variable.

For instance, let's assume you have created the ``/path/to/edx-platform/lms/envs/mysettings.py`` and ``/path/to/edx-platform/cms/envs/mysettings.py`` modules. These settings should be pretty similar to the following files::

    $(tutor config printroot)/env/apps/openedx/tutor/lms/development.py
    $(tutor config printroot)/env/apps/openedx/tutor/cms/development.py

Alternatively, the ``mysettings.py`` files can import the tutor development settings::

    # Beginning of mysettings.py
    from .tutor.development import *

You should then specify the settings to use on the host::

    export TUTOR_EDX_PLATFORM_SETTINGS=mysettings

From then on, all ``dev`` commands will use the ``mysettings`` module. For instance::

    tutor dev runserver lms

Running edx-platform unit tests
-------------------------------

It's possible to run the full set of unit tests that ship with `edx-platform <https://github.com/edx/edx-platform/>`__. To do so, you should first build the "test" target of the "openedx-dev" Docker image::

    tutor images build --target=test openedx-dev

.. warning::
    Don't forget to re-build the development image afterwards if you'd like to run ``dev`` commands again! To do so, run ``tutor images build openedx-dev`` after you are done testing.

Then, run unit tests with ``pytest`` commands::

    # Run a test container
    tutor dev run lms bash

    # Run tests on common apps
    unset DJANGO_SETTINGS_MODULE
    export EDXAPP_TEST_MONGO_HOST=mongodb
    pytest common
    pytest openedx

    # Run tests on LMS
    export DJANGO_SETTINGS_MODULE=lms.envs.tutor.test
    pytest lms

    # Run tests on CMS
    export DJANGO_SETTINGS_MODULE=cms.envs.tutor.test
    pytest cms

.. note::
    Getting all edx-platform unit tests to pass on Tutor is currently a work-in-progress. Some unit tests are still failing. If you manage to fix some of these, please report your findings in the `Tutor forums <https://discuss.overhang.io>`__.
