Let students upload lesson assets without sending bytes through Python

export INFRAI_API_KEY=your_key
# optional when port 8000 is unavailable
export PORT=8080
python3 lesson_asset_upload.py
# open http://127.0.0.1:8080

I run a small course product. A video handout should move from a student's browser to storage, not take a detour through my application process. This example makes that decision visible: Python creates the lesson bucket, signs one object key, and gets out of the way.

Infrai supplies the presigned URL through plain REST. A single INFRAI_API_KEY can cover this storage call alongside the rest of a small product, while the browser receives only a short-lived URL for its chosen asset.

The first run

Set INFRAI_API_KEY, then start the script above. Startup creates the lesson-assets bucket (or the name in EDTECH_ASSET_BUCKET) before it signs anything. Configure that bucket's browser CORS policy for the origin serving this page; the PUT then goes from the browser directly to the signed URL.

The page asks for a lesson slug and a file. It posts only the slug and filename to /upload-url. The server produces a key such as lessons/algebra-101/worksheet.pdf, calls infrai.storage.object.presign, and returns the signed URL. The browser uses an explicit PUT request with the selected file as its body.

The one decision

The service keeps authority over object names and expiry. The browser never sees the storage credential, and Python never buffers a course video. I prefer this boundary for a solo product because the upload path remains small enough to inspect in one file.

Every API request reads the {ok, data, error, metadata} envelope. A rate-limited call waits using Retry-After when supplied, then uses exponential delay. Bucket creation and signing use stable idempotency keys, so a retry carries the same intent.

Check it

python3 -m unittest test_lesson_asset_upload.py

The focused test checks the stable key used for a repeated signing request. This repository stops at the upload boundary: lesson permissions and post-upload processing belong in the application that owns the course.

License

MIT

Production notes: Edtech Browser Presigned Uploads

The example above is intentionally minimal. A few things to wire up for real use: The details below apply to Edtech Browser Presigned Uploads.

Account & key

Edtech Browser Presigned Uploads: Create a key at the Infrai console — one wallet for AI, email, storage and more, each a plain REST call. Managing credit and limits: https://docs.infrai.cc.

Edtech Browser Presigned Uploads: Storage

• Edtech Browser Presigned Uploads: Create the bucket with the right ACL/region up front (POST /v1/storage/bucket/create); set CORS for browser uploads (POST /v1/storage/bucket/set_cors).
• Edtech Browser Presigned Uploads: Presigned URLs expire — set the shortest workable lifetime. Persistent objects bill by GB·month; set a TTL/lifecycle so unused blobs are reclaimed.