Upload large files to Google Cloud Storage using resumable uploads and generate signed URLs for temporary access

Steps

1. Authenticate using a service account key or Application Default Credentials (ADC); obtain an OAuth2 access token with scope https://www.googleapis.com/auth/devstorage.read_write
2. Initiate a resumable upload by sending a POST to https://storage.googleapis.com/upload/storage/v1/b/{bucket}/o?uploadType=resumable with the Content-Type header set to the object's MIME type and an X-Goog-Upload-Command: start header; the response Location header contains the session URI
3. Upload file data in chunks (recommended 8 MiB aligned chunks) by sending PUT requests to the session URI with Content-Range headers specifying byte range and total size; retry any 5xx or network failure from the last committed byte
4. Finalize the upload by sending the last chunk with Content-Range indicating the final byte; a 200 or 201 response confirms the object is committed
5. Generate a signed URL for temporary object access using the GCS Signing API or client libraries: specify expiration (max 7 days for service-account-signed V4 URLs), HTTP method, and optionally required headers; sign the canonical request with the service account private key
6. For short-lived access patterns, prefer V4 signed URLs (signBlob API or client library) and set the Content-Disposition or response-content-type query params to control browser behavior