Welcome to our Sherlock Holmes-inspired tech adventure series! In this journey, every technical challenge is a thrilling mystery just waiting to be solved. Much like Sherlock Holmes, known for his sharp eye for detail and his ability to deduce the hidden truth, we’ll tackle problems with wit, precision, and a bit of detective work. So, grab your magnifying glass, and let’s crack these cases together!
The Early Morning Disturbance
It was 4 a.m. when I received an urgent call from a colleague. Our Lambda function, crucial for our project, had suddenly stopped working. Half-awake but alert, I jumped into action, ready to investigate the issue with the urgency it demanded. The error logs pointed to an unusual message: npm ERR! rofs EROFS: read-only file system, mkdir '/home/sbx_user1051'.
The First Clue: A Read-Only File System
At first glance, the error was puzzling. It seemed clear that npm was trying to write to a read-only file system. But why would this happen suddenly, especially when our setup had been running smoothly for weeks? I immediately reviewed our recent code changes, suspecting that perhaps we had inadvertently introduced something that tried to write to the file system. However, a careful inspection of the code revealed no such changes.
The problem wasn’t in the code itself—but something else was at play.
The Google Search: A Trail of Breadcrumbs
With no answers in the code, I turned to the vast knowledge of the internet. I knew there had to be someone else who had faced this issue before. After some digging, I stumbled upon a Stack Overflow post where a developer had suggested setting the environment variable NPM_CONFIG_CACHE=/tmp/.npm to resolve a similar issue. At this point, I wasn’t sure why this would work, but I decided to try it.
To my surprise, the solution worked—our Lambda function sprang back to life. But the real mystery was just beginning: why did this seemingly simple change solve the problem?
The Curious Case of the Environment Variable
Curiosity got the better of me, and I spent the next two hours digging deeper into npm’s documentation and GitHub repositories. I learned that npm version 8, which was released recently, introduced a change in the @npmcli/run-script module. This change caused npm to write scripts into the temporary directory (tmpdir()) under the user path (/home/sbx_user1051). While this might seem like a small modification, it had unintended consequences when Lambda’s environment didn’t allow writing to that location. The solution—redirecting npm’s cache to a different directory—worked because it bypassed the permissions issue that had cropped up.
This discovery wasn’t just interesting—it was crucial. It explained why setting the NPM_CONFIG_CACHE environment variable to /tmp/.npm resolved the issue, but it also raised further questions about how and why this happened.
The Final Piece of the Puzzle
But here’s where things get even more intriguing. The question remained: why did this problem suddenly emerge? Why had everything been working fine up until now? After some additional research, I found the missing piece of the puzzle. It turns out that AWS Lambda had recently deprecated Node.js 14 and automatically upgraded our environment to the latest version, which included npm 8. This upgrade had introduced the change in npm’s behavior that caused our problem with the read-only file system.
What initially seemed like an obscure error message was, in fact, the result of an environment change we hadn’t anticipated. AWS’s upgrade triggered the issue, but we were able to solve it by adapting to the new version’s requirements.
Conclusion
In the end, what started as a simple error message turned out to be a deeper mystery rooted in a change to our development environment. This case serves as a reminder that sometimes, the answers are not in the code itself, but in the systems and tools we rely on. In future cases, we’ll continue to investigate these infrastructure mysteries, one clue at a time.
Stay tuned for our next adventure! Until then, keep your magnifying glasses handy and your curiosity alive. There are always new mysteries to unravel.