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.

First-time setup

Firstly, either install Tutor (for development against the named releases of Open edX) or install Tutor Nightly (for development against Open edX’s master branches).

Then, optionally, tell Tutor to use a local fork of edx-platform.:

tutor mounts add ./edx-platform

Then, launch the developer platform setup process:

tutor images build openedx-dev
tutor dev launch

This will perform several tasks. It will:

• build the “openedx-dev” Docker image, which is based on the “openedx” production image but is specialized for developer usage (eventually with your fork),

• stop any existing locally-running Tutor containers,

• disable HTTPS,

• set LMS_HOST to local.overhang.io (a convenience domain that simply points at 127.0.0.1),

• prompt for a platform details (with suitable defaults),

• build an openedx-dev image,

• start LMS, CMS, supporting services, and any plugged-in services,

• ensure databases are created and migrated, and

• run service initialization scripts, such as service user creation and Waffle configuration.

Additionally, when a local clone of edx-platform is bind-mounted, it will:

• re-run setup.py,

• clean-reinstall Node modules, and

• regenerate static assets.

Once setup is complete, the platform will be running in the background:

• LMS will be accessible at http://local.overhang.io:8000.

• CMS will be accessible at http://studio.local.overhang.io:8001.

• Plugged-in services should be accessible at their documented URLs.

Now, use the tutor dev ... command-line interface to manage the development environment. Some common commands are described below.

Note

If you’ve added your edx-platform to the bind-mounted folders, you can remove at any time by running:

tutor mounts remove ./edx-platform

At any time, check your configuration by running:

tutor mounts list

Read more about bind-mounts below.

Stopping the platform

To bring down the platform’s containers, simply run:

tutor dev stop

Starting the platform back up

Once first-time setup has been performed with launch, the platform can be started going forward with the lighter-weight start -d command, which brings up containers detached (that is: in the background), but does not perform any initialization tasks:

tutor dev start -d

Or, to start with platform with containers attached (that is: in the foreground, the current terminal), omit the -d flag:

tutor dev start

When running containers attached, stop the platform with Ctrl+c, or switch to detached mode using Ctrl+z.

Finally, the platform can also be started back up with launch. It will take longer than start, but it will ensure that config is applied, databases are provisioned & migrated, plugins are fully initialized, and (if applicable) the bind-mounted edx-platform is set up. Notably, launch is idempotent, so it is always safe to run it again without risk to data. Including the --pullimages flag will also ensure that container images are up-to-date:

tutor dev launch --pullimages

Debugging with breakpoints

To debug a local edx-platform repository, add a python breakpoint with breakpoint() anywhere in the code. Then, attach to the applicable service’s container by running start (without -d) followed by the service’s name:

# Debugging LMS:
tutor dev start lms

# Or, debugging CMS:
tutor dev start cms

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 rebuild assets, you can use the openedx-assets command that ships with Tutor:

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

Rebuilding the openedx-dev image

The openedx-dev Docker image is based on the same openedx image used by tutor local ... to run LMS and CMS. However, it has a few differences to make it more convenient for developers:

• The user that runs inside the container has the same UID as the user on the host, 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, ipdb, vim, telnet.

• The edx-platform development requirements are installed.

If you are using a custom openedx image, then you will need to rebuild openedx-dev every time you modify openedx. To so, run:

tutor images build openedx-dev

Alternatively, the image will be automatically rebuilt every time you run:

tutor dev launch

Sharing directories with containers

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.

Persistent bind-mounted volumes with tutor mounts

tutor mounts is a set of Tutor command to manage bind-mounted host directories. Directories are mounted both at build time and run time:

• At build time: some of the host directories will be added the Docker build context. This makes it possible to transparently build a Docker image using a locally checked-out repository.

• At run time: host directories will be bind-mounted in running containers, using either an automatic or a manual configuration.

After some directories have been added with tutor mounts add, all tutor dev and tutor local commands will make use of these bind-mount volumes.

Values passed to tutor mounts add ... can take one of two forms. The first is explicit:

tutor mounts add lms:/path/to/edx-platform:/openedx/edx-platform

The second is implicit:

tutor mounts add /path/to/edx-platform

With the explicit form, the value means “bind-mount the host folder /path/to/edx-platform to /openedx/edx-platform in the lms container at run time”.

If you use the explicit format, you will quickly realise that you usually want to bind-mount folders in multiple containers at a time. For instance, you will want to bind-mount the edx-platform repository in the “cms” container, but also the “lms-worker” and “cms-worker” containers. To do that, write instead:

# each service is added to a coma-separated list
tutor mounts add lms,cms,lms-worker,cms-worker:/path/to/edx-platform:/openedx/edx-platform

This command line is a bit cumbersome. In addition, with this explicit form, the edx-platform repository will not be added to the build context at build time. But Tutor can be smart about bind-mounting folders to the right containers in the right place when you use the implicit form of the tutor mounts add command. For instance, the following implicit form can be used instead of the explicit form above:

tutor mounts add /path/to/edx-platform

With this implicit form, the edx-platform repo will be bind-mounted in the containers at run time, just like with the explicit form. But in addition, the edx-platform will also automatically be added to the Docker image at build time.

To check whether you have used the correct syntax, you should run tutor mounts list. This command will indicate whether your folders will be bind-mounted at build time, run time, or both. For instance:

$ tutor mounts add /path/to/edx-platform
$ tutor mounts list
- name: /home/data/regis/projets/overhang/repos/edx/edx-platform
build_mounts:
- image: openedx
  context: edx-platform
- image: openedx-dev
  context: edx-platform
compose_mounts:
- service: lms
  container_path: /openedx/edx-platform
- service: cms
  container_path: /openedx/edx-platform
- service: lms-worker
  container_path: /openedx/edx-platform
- service: cms-worker
  container_path: /openedx/edx-platform
- service: lms-job
  container_path: /openedx/edx-platform
- service: cms-job
  container_path: /openedx/edx-platform

So, when should you not be using the implicit form? That would be when Tutor does not know where to bind-mount your host folders. For instance, if you wanted to bind-mount your edx-platform virtual environment located in ~/venvs/edx-platform, you should not write mounts add ~/venvs/edx-platform, because that folder would be mounted in a way that would override the edx-platform repository in the container. Instead, you should write:

tutor mounts add lms:~/venvs/edx-platform:/openedx/venv

Verify the configuration with the list command:

$ tutor mounts list
- name: lms:~/venvs/edx-platform:/openedx/venv
  build_mounts: []
  compose_mounts:
  - service: lms
    container_path: /openedx/venv

Note

Remember to setup your edx-platform repository for development! See First-time setup.

Copy files from containers to the local filesystem

Sometimes, you may want to modify some of the files inside a container for which you don’t have a copy on the host. A typical example is when you want to troubleshoot a Python dependency that is installed inside the application virtual environment. In such cases, you want to first copy the contents of the virtual environment from the container to the local filesystem. To that end, Tutor provides the tutor dev copyfrom command. First, copy the contents of the container folder to the local filesystem:

tutor dev copyfrom lms /openedx/venv ~

Then, bind-mount that folder back in the container with the MOUNTS setting (described above):

tutor mounts add lms:~/venv:/openedx/venv

You can then edit the files in ~/venv on your local filesystem and see the changes live in your “lms” container.

Manual bind-mount to any directory

Warning

Manually bind-mounting volumes with the --volume option makes it difficult to simultaneously bind-mount to multiple containers. Also, the --volume options are not compatible with start commands. For an alternative, see the persistent mounts.

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 repository. In such cases, you can simply use the -v/--volume Docker option:

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

Override docker-compose volumes

Adding items to the MOUNTS setting effectively adds new bind-mount volumes to the docker-compose.yml files. But you might want to have more control over your volumes, such as adding read-only options, or customising other fields of the different services. 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.

Note

The tutor local commands load the docker-compose.override.yml file from the $(tutor config printroot)/env/local/docker-compose.override.yml directory. One-time jobs from initialisation commands load the local/docker-compose.jobs.override.yml and dev/docker-compose.jobs.override.yml.

Common tasks

XBlock and edx-platform plugin development

In some cases, you will have to develop features for packages that are pip-installed next to the 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 start. Every change made to the mypackage folder will be picked up and the development server will be automatically reloaded.

Running edx-platform unit tests

It’s possible to run the full set of unit tests that ship with edx-platform. To do so, run a shell in the LMS development container:

tutor dev run lms bash

Then, run unit tests with pytest commands:

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

# 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 Open edX forum.