Signed Download URLs
Explore how to generate signed download URLs using AWS Lambda to securely control access to files stored in S3. Understand why you need separate URLs for upload and download, how to configure access controls, and the importance of temporary credential expiry. By the end, you will be able to implement secure, time-limited URLs for file downloads in serverless applications.
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Another URL is required #
In the previous chapter, you used the same URL for both the form display function and the form processing function. This was possible because the browser web form workflow used two different HTTP methods. To display the form, it sent a GET request. To upload the submission details, it sent a POST request. Because S3 redirects work as GET method calls, you cannot use the same URL with different methods anymore. The browser will send a POST request directly to S3, which will redirect to another URL. You’ll need a different URL to handle that redirect, so you can create a new API endpoint.
When S3 sends ...