build: copy from node_modules using NPM postinstall hook, not Paver

[kdmccormick]

During the review of ADR 17 [1], Régis pointed out [2] that the shell script which replaces Paver's process_npm_assets could be automatically invoked as an NPM post-install hook, ensuring that the step is seamlessly executed whenever npm install is run. I had avoided using that suggestion, as I worried that it would make it harder to move node_modules out of the edx-platform directory in Tutor's openedx image.

Since then, two things have changed. Firstly, Tutor v16's new persistent mounts interface [3] has lessened the importance of moving node_modules. Secondly, I have realized that using a post-install hook would not preclude us from modifying the underlying script (scripts/copy-node-modules.sh) to look in an alternative location for node_modules, should that end up being something we want to do.

This commit modifies the ADR based on those findings, stubs out Paver's process_npm_assets, and adds the suggested post-install hook and replacement Bash script.

References:

1. https://github.com/openedx/edx-platform/blob/master/docs/decisions/0017-reimplement-asset-processing.rst
2. docs: add ADR: "Reimplement edx-platform static asset processing" #31790 (comment)
3. https://github.com/overhangio/tutor/blob/master/CHANGELOG.md#v1600-2023-06-14

Part of: #31604

Testing

I tested this by comparing the exact node_modules asset copies, as generated by the old Paver command versus this new shell script & post-install hook.

Using latest Tutor Nightly and a recently-pulled openedx image:

# ensure latest master & clean slate
cd edx-platform
git switch master
git pull
git clean -f common/static

# we'll use compare_common_static to hold the contents of common/static in a few different scenarios
rm -rf compare_common_static
mkdir compare_common_static

# scenario A: output from the current image
tutor local copyfrom lms common/static compare_common_static/image

tutor mounts add .

# scenario B: output from old paver task on master
git switch master
tutor local run lms openedx-assets npm
cp -r common/static compare_common_static/paver

# scenario C: output from new copy-node-modules shell script
git switch kdmccormick/copy-node-modules
tutor local run lms scripts/copy-node-modules.sh
tutor local copyfrom lms common/static compare_common_static/shell

# scenario D: output from new copy-node-modules shell script, invoked by npm post-install hook
git switch kdmccormick/copy-node-modules
tutor local run lms npm install
tutor local copyfrom lms common/static compare_common_static/npm-install

# compare out of all scenarios -- they should be the exact same! (diff should have no output)
cd compare_common_static
diff -r image paver
diff -r image shell
diff -r image npm-install

[kdmccormick]

@regisb Would you remind reviewing this one?

[regisb]

I did not test the change but I think I understand what is going on :) Looks good to me! I appreciate the fact that you made node_modules future-proof with an ad-hoc parameter.

[edx-pipeline-bot]

2U Release Notice: This PR has been deployed to the edX staging environment in preparation for a release to production.

[edx-pipeline-bot]

2U Release Notice: This PR has been deployed to the edX production environment.

[edx-pipeline-bot]

2U Release Notice: This PR has been deployed to the edX production environment.

[edx-pipeline-bot]

2U Release Notice: This PR has been deployed to the edX staging environment in preparation for a release to production.

[edx-pipeline-bot]

2U Release Notice: This PR has been deployed to the edX production environment.