** Here’s what I learned.**

It wasn’t a sophisticated attack or a major infrastructure meltdown.
It was a simple IAM permission change I thought was “low risk.”

The result? A critical data pipeline ground to a halt, and our monitoring lit up with red.

I was tightening security—applying the principle of least privilege to an S3 bucket policy. What I overlooked was one service account that needed write access during the final stage of an ETL job. A small oversight, a big impact.

Moments like this are humbling, but they’re also where real growth happens. Here’s what I’m taking away so it doesn’t happen again:

🔍 Audit before you restrict
Always check “Last Accessed” logs and trace actual usage before narrowing permissions. If something might be in use, assume it is.

🧪 Test in staging—every time
Even what seems like a minor IAM change should be validated in a sandbox first. Breaking something in staging is a lesson; breaking it in production is an incident.

🔄 Small changes, frequent iterations
Bundle fewer changes together. Doing them one at a time makes it clear exactly what caused an issue—and speeds up recovery.

Security and DevOps are about continuous learning. Sometimes, you truly learn how to protect a system by seeing how it breaks when you least expect it.

To my fellow engineers: What’s the “smallest” change you’ve made that caused the biggest ripple?

Let’s keep sharing these stories. It’s how we build resilience—and better systems. 🛠️

SoftwareEngineering #DevSecOps #CloudSecurity #DataEngineering #LessonsLearned #FailureIsALeacher #DevOps #AWS #IAM