Hi @alirz ,
Welcome to Google Cloud Community!
The Signed Policy Document method is still supported and recommended by Google Cloud Storage for secure, direct file uploads from a browser using HTTP POST. Google Cloud client libraries, like the Node.js SDK, offer methods such as generateSignedPostPolicyV2 and generateSignedPostPolicyV4, showing that this approach is still valid and useful.
However, it’s important to note the limitation: even though your backend only needs to generate the policy once, each file must still be uploaded in a separate POST request. So, if you’re uploading 1000+ files, the client still needs to send 1000+ POST requests—one per file. The policy simplifies authentication, but it doesn’t allow you to upload multiple files in a single request.
For the specific use case of uploading 1000 or more files, the Google Cloud Storage Transfer Manager, when utilized from your backend, represents a recommended approach. The Transfer Manager allows your backend to upload many files efficiently using a single main credential (like Application Default Credentials). This simplifies server-side authentication and management. However, it’s important to note that each file is still uploaded individually to Google Cloud Storage (GCS), not as part of a single, multi-file HTTP request from the client.
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