title: How to transfer data that does not fit in ram from a microcontroller to AWS using direct s3 upload?
body: <p>I need to transfer some data files from an stm32 microcontroller to an AWS S3 bucket. My microcontroller is connected via UART to an esp32-s2. I was planning to use s3 direct upload to do this that used HTTP to upload a file. However, I only have limited RAM (some kbs) and I need to transfer files around 100MM. I have looked into HTTP stream, that would allow me to send my files in small chunks but I do not know how to create a request that would work as I need to transfer the file content but also a set a form fields (e.g. 'x-amz-security-token', 'signature', ...) for my request to be accepted by AWS. Is it possible to achieve this using HTTP so that I can use the direct upload mechanism from S3? or should I look into other ways, for example sending pieces of my files through a websocket and reconstructing them on the AWS side in a lambda to then store them in S3.</p>
  <p>Thank you in advance for your help.</p>