Serverless computing is about short functions that run fast and only for a short duration. On the other hand, files can be arbitrarily large, and sending them through ephemeral functions can easily hit a limit of the runtime.
This is the problem S3 signed URLs solve.
Learn how to implement a serverless-friendly, robust, and secure solution to handle files using signed URLs.
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Serverless functions are designed to be run for a short duration, handle small amounts of data, then terminate quickly. This is great to provide an HTTP API that users can call to interact with your app but is terrible for large downloads or uploads.
S3 on the other hand is to handle arbitrarily large files and can handle long downloads and uploads and terabytes of data.
URL signing is a mechanism to combine the best parts of the two services. The Lambda function decides who and how can download and upload files, but the actual transfer is handled by the S3 service.
When I started working with signed URLs I quickly realized how easy it is to end up with a solution that is not reliable and not secure. This prompted me to learn how it works and what services are taking part.
Signed URLs change how you think about files and access control.
And the best part is that this knowledge is transferrable between clouds. The services and the details are different, but the underlying mechanism is the same for all providers that offer this functionality.
This book is a thorough introduction to signed URLs. You'll learn:
Chapter 1: Overview
From servers to serverless
Signed URLs for S3
Security of S3 signed URLs
Chapter 2: Implementation
Backend with Node.js
Chapter 3: Specific use-cases
Least privilege with dedicated roles
Using HTTP redirects
How to check if a file exists before signing
How to set the filename
Integrate with CloudFront
Handling encrypted data
I'm a software developer focusing mostly on cloud computing and web technologies. I'm especially interested in how to handle edge cases to end up with dependable software.
One of my main focus is security and how each part affects the whole system. I'm an AWS-certified security specialist.
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