Building a Secure Serverless Upload Pattern on AWS with Terraform 🚀

𝗗𝗶𝗿𝗲𝗰𝘁 𝘂𝗽𝗹𝗼𝗮𝗱𝘀. 𝗭𝗲𝗿𝗼 𝗯𝗮𝗰𝗸𝗲𝗻𝗱 𝗯𝗼𝘁𝘁𝗹𝗲𝗻𝗲𝗰𝗸𝘀. 𝗘𝗻𝘁𝗲𝗿𝗽𝗿𝗶𝘀𝗲-𝗴𝗿𝗮𝗱𝗲 𝘀𝗲𝗰𝘂𝗿𝗶𝘁𝘆. 🧠 𝗔 𝗥𝗲𝗮𝗹-𝗪𝗼𝗿𝗹𝗱 𝗣𝗿𝗼𝗯𝗹𝗲𝗺 (𝗧𝗵𝗮𝘁 𝗜 𝗞𝗲𝗲𝗽 𝗦𝗲𝗲𝗶𝗻𝗴) A few weeks ago, I was reviewing a system where users were uploading files (some >300MB). The original flow looked “reasonable”: Frontend uploads the file to the backend Backend processes the request Backend uploads the file to S3 Backend responds But in practice, the system was 𝗳𝗮𝗹𝗹𝗶𝗻𝗴 𝗮𝗽𝗮𝗿𝘁: ❌ Timeouts ❌ Lambda memory spikes ❌ High AWS bills ❌ Angry users And the root cause was always the same: 𝗧𝗵𝗲 𝗯𝗮𝗰𝗸𝗲𝗻𝗱 𝘀𝗵𝗼𝘂𝗹𝗱 𝗡𝗘𝗩𝗘𝗥 𝗵𝗮𝗻𝗱𝗹𝗲 𝗳𝗶𝗹𝗲 𝘂𝗽𝗹𝗼𝗮𝗱𝘀 𝗶𝗻 𝗮 𝘀𝗲𝗿𝘃𝗲𝗿𝗹𝗲𝘀𝘀 𝗮𝗿𝗰𝗵𝗶𝘁𝗲𝗰𝘁𝘂𝗿𝗲. 💡 𝗧𝗵𝗲 𝗣𝗮𝘁𝘁𝗲𝗿𝗻 𝗧𝗵𝗮𝘁 𝗙𝗶𝘅𝗲𝘀 𝗘𝘃𝗲𝗿𝘆𝘁𝗵𝗶𝗻𝗴 The solution is a 𝘄𝗲𝗹𝗹-𝗸𝗻𝗼𝘄𝗻 𝗯𝘂𝘁 𝗼𝗳𝘁𝗲𝗻 𝗺𝗶𝘀𝘂𝘀𝗲𝗱 𝗽𝗮𝘁𝘁𝗲𝗿𝗻: 👉 𝗦𝟯 𝗣𝗿𝗲𝘀𝗶𝗴𝗻𝗲𝗱 𝗨𝗥𝗟𝘀 Instead of uploading files 𝘵𝘩𝘳𝘰𝘶𝘨𝘩 your backend, you let the client upload 𝗱𝗶𝗿𝗲𝗰𝘁𝗹𝘆 𝘁𝗼 𝗦𝟯, but in a 𝗰𝗼𝗻𝘁𝗿𝗼𝗹𝗹𝗲𝗱, 𝘁𝗲𝗺𝗽𝗼𝗿𝗮𝗿𝘆, 𝗮𝗻𝗱 𝘀𝗲𝗰𝘂𝗿𝗲 𝘄𝗮𝘆. This is the same pattern used by: ● Fintech platforms ● Healthcare systems ● Large SaaS products 🧩 𝗛𝗼𝘄 𝘁𝗵𝗲 𝗔𝗿𝗰𝗵𝗶𝘁𝗲𝗰𝘁𝘂𝗿𝗲 𝗪𝗼𝗿𝗸𝘀 𝗛𝗶𝗴𝗵-𝗹𝗲𝘃𝗲𝗹 𝗳𝗹𝗼𝘄: 1️⃣ Client asks pe