fix: make "fs" service available in XBlock preview module system

[ArturGaspar]

Description

The "fs" XBlock runtime service is not made available in Palm when in preview mode (e.g. in Studio).

This causes an error when trying to use this service while editing an XBlock, e.g. uploading a screenshot for the Recommender XBlock:

Traceback

Traceback (most recent call last):
  File "/openedx/edx-platform/./cms/djangoapps/contentstore/views/preview.py", line 75, in preview_handler
    resp = instance.handle(handler, req, suffix)
  File "/openedx/venv/lib/python3.8/site-packages/xblock/mixins.py", line 84, in handle
    return self.runtime.handle(self, handler_name, request, suffix)
  File "/openedx/edx-platform/xmodule/x_module.py", line 1033, in handle
    return super().handle(block, handler_name, request, suffix=suffix)
  File "/openedx/venv/lib/python3.8/site-packages/xblock/runtime.py", line 1081, in handle
    results = handler(request, suffix)
  File "/openedx/venv/lib/python3.8/site-packages/recommender/recommender.py", line 581, in upload_screenshot
    fhwrite = self.fs.open(file_name, "wb")
  File "/openedx/venv/lib/python3.8/site-packages/xblock/reference/plugins.py", line 141, in __get__
    value = xblock.runtime.service(xblock, 'fs').load(self, xblock)
  File "/openedx/edx-platform/xmodule/x_module.py", line 1810, in service
    service = self._module_system.service(block, service_name)
  File "/openedx/edx-platform/xmodule/x_module.py", line 1740, in service
    service = super().service(block=block, service_name=service_name)
  File "/openedx/venv/lib/python3.8/site-packages/xblock/runtime.py", line 1125, in service
    raise NoSuchServiceError(f"Service {service_name!r} is not available.")
xblock.exceptions.NoSuchServiceError: Service 'fs' is not available.

This is fixed in master, possibly in 18fea86, however that is part of openedx#31472 which is a rather large change. This is a smaller fix.

Testing instructions

1. Install and enable the Recommender XBlock

   • Install RecommenderXBlock from https://github.com/open-craft/RecommenderXBlock/tree/opencraft-release/2.1.0 if using S3
   • Make sure that openedx-django-pyfs is configured to use a writeable local directory, or an S3 bucket e.g.

     # lms/envs/private.py
     DJFS = {
         'type': 'osfs',
         'directory_root': 'lms/static/djpyfs',
         'url_root': '/static/djpyfs'
     }
     # cms/envs/private.py
     DJFS = {
         'type': 'osfs',
         'directory_root': 'cms/static/djpyfs',
         'url_root': '/static/studio/djpyfs'
     }
     # Or,
     DJFS = {
         'type': 's3fs',
         'bucket': AWS_STORAGE_BUCKET_NAME,
         'prefix': 'pyfs/',
         # Note that explicitly passing credentials requires openedx-django-pyfs >= 3.4.1
         'aws_access_key_id': AWS_ACCESS_KEY_ID,
         'aws_secret_access_key': AWS_SECRET_ACCESS_KEY
     }

2. In Studio, add a recommender component to a course.

3. Add a resource in the recommender component, upload a preview screenshot.

   Details

   

4. Save it. Make sure there are no errors and that it was saved correctly.

5. Reload the page. See the newly added item and that the screenshot loads on hover.

Deadline

None

Other information

Private-ref: https://tasks.opencraft.com/browse/BB-8077

[ArturGaspar]

Need to merge open-craft/RecommenderXBlock#1 to fix the build for this.

[viadanna]

Just a few small changes and we're good to go

[viadanna]

Sorry I didn't mention this, but this is added via Grove, we don't need it in all our instances

[viadanna]

Can you remove the reference to openedx-django-pyfs in base.in?

[ArturGaspar]

@viadanna There is no direct reference to openedx-django-pyfs in base.in, it is pulled by the xblock requirement.

[viadanna]

Alright, that's where we need to bump openedx-django-pyfs

[ArturGaspar]

Done.

[Cup0fCoffee]

👍

• I tested this
• I read through the code
• [n/a] I checked for accessibility issues
• [n/a] Includes documentation
• I made sure any change in configuration variables is reflected in the corresponding client's configuration-secure repository.

Changes done but Paulo is on holidays.

[Cup0fCoffee]

👍