tutor-contrib-s3scorm 21.2.0

How it works

This plugin will add a reverse proxy statement to the lms matcher in the Caddyfile, so that requests to LMS_BASE/scorm/ will be proxied to the S3 endpoint corresponding to the bucket. This will cause that all SCORM assets will be served from the same origin url as the LMS. The effect is that the scorm components will be able to access the api located at the parent window.

To have the

Installation

pip install tutor-contrib-s3scorm

This release targets Tutor 21 / Open edX Ulmo.

Configuration

This plugin integrates with tutor-contrib-s3. By default, S3SCORM_BUCKET inherits the value of S3_STORAGE_BUCKET if that setting is defined. You only need to set S3SCORM_BUCKET explicitly when SCORM files live in a different bucket.

These parameters are used by the plugin:

• S3SCORM_BUCKET (optional): name of the bucket (e.g., openedx-my-file-bucket). Defaults to S3_STORAGE_BUCKET if that variable is defined.

• S3SCORM_ENDPOINT (optional): S3 endpoint. E.g., s3.us-east-1.amazonaws.com. If unset, the plugin falls back to S3_HOST and S3_PORT, then s3.<S3_REGION>.amazonaws.com.

• S3SCORM_PATH (optional): Path inside the bucket where the ‘scorm’ directory is located. Include a leading slash and no trailing slash (e.g. “/openedx/media”). Defaults to empty path (root of the bucket).

• S3SCORM_URL_STYLE (optional): How the upstream bucket is addressed. Use virtual for <bucket>.<endpoint> and path for <endpoint>/<bucket>. Defaults to virtual.

Optional parameters:

• S3SCORM_USE_SSL: Default true.

When S3SCORM_PATH is set, the proxy preserves the public /scorm/... URL and rewrites the upstream request to <S3SCORM_PATH>/scorm/... inside the bucket. The upstream endpoint is resolved in this order: S3SCORM_ENDPOINT, S3_HOST plus S3_PORT if set, and finally s3.<S3_REGION>.amazonaws.com. When S3SCORM_URL_STYLE is set to path, the bucket is placed in the upstream URI path instead of the hostname.

Performance: caching, compression and CDN

By default, the SCORM XBlock itself never generates /scorm/... URLs at all: it links to its own .../handler/assets_proxy/... endpoint, which streams every asset through the LMS/ CMS Django process regardless of storage backend. That means the /scorm/* Caddy route this plugin installs sits unused until the xblock is told to link to storage URLs directly instead — which only happens once S3SCORM_CLOUDFRONT_DOMAIN is set (see below). Once that switch is flipped, every SCORM asset request is proxied by Caddy straight to S3 (or the CDN in front of it) on each and every request, with no caching or compression unless configured. For courses with SCORM packages containing video, audio or many images this adds up: assets are re-fetched in full on every page load, and text assets (JS/HTML/JSON) are sent uncompressed. The following settings address this without changing how access is controlled — the LMS/CMS still decide who ever reaches a page that embeds the SCORM block in the first place, since these XBlocks are only rendered on pages already gated by the standard enrollment/authentication checks.

• S3SCORM_CACHE_MAX_AGE (optional, default 86400): adds a Cache-Control: public, max-age=<value>, immutable header to SCORM asset responses so browsers stop re-downloading unchanged assets on every visit. Set to 0 to disable the header entirely (previous behavior). Because SCORM asset paths are keyed by block usage id and are typically overwritten in place when a course team re-uploads a package, keep this conservative unless your asset paths are otherwise versioned; raise it (e.g. to 31536000 for a year) once you’re confident republishing isn’t a concern, or your pipeline invalidates/versions asset paths on republish.

• S3SCORM_COMPRESS (optional, default true): has Caddy transparently compress (zstd/gzip) text-based SCORM assets (the SCORM package’s own JS/HTML/CSS/JSON) on the fly. Binary assets such as video and images are left as-is. Set to false to disable.

• S3SCORM_CLOUDFRONT_DOMAIN (optional, default empty): the domain name of a CDN distribution (e.g. a CloudFront distribution) that has the SCORM bucket configured as its origin. When set, Caddy proxies /scorm/* to this domain instead of talking to S3 directly, so requests benefit from edge caching, edge compression and reduced load on the origin bucket — while assets are still served from the same origin as the LMS/CMS, so the SCORM grading postMessage API continues to work exactly as described above. When this is set, S3SCORM_ENDPOINT/S3SCORM_URL_STYLE/bucket-address settings are ignored for upstream addressing (S3SCORM_PATH still applies if your distribution’s origin path mirrors the bucket layout).

  Setting S3SCORM_CLOUDFRONT_DOMAIN also switches XBLOCK_SETTINGS["ScormXBlock"] ["PROXY_ASSETS_LMS"] to False, which is what actually makes the xblock link to /scorm/... storage URLs instead of its built-in assets_proxy handler in the first place — without a CDN configured, this plugin leaves PROXY_ASSETS_LMS untouched (its default, True) and assets keep flowing through Django as before. In other words, the caching/compression settings above only take effect once a CDN domain is set here.

Example, adding a CDN and a one-year cache lifetime on top of the base configuration:

tutor config save \
    --set S3SCORM_CLOUDFRONT_DOMAIN=d123456abcdef8.cloudfront.net \
    --set S3SCORM_CACHE_MAX_AGE=31536000

Usage

tutor plugins enable s3scorm

License

This software is licensed under the terms of the AGPLv3.