MicroVMs
The CORS Header Is Present Twice and That Is Why It Fails
You added the header at the proxy, your framework was already sending it, and the browser now rejects both. Duplicates are invalid, not additive.
MicroVMs
Debugging Production Without Touching Production
The bug only reproduces with real state. Copying the database loses the parts that matter. Cloning the whole machine keeps them.
MicroVMs
I Let an Agent Run rm -rf and Nothing Bad Happened
The question is not whether an autonomous agent will do something destructive. It is what the destruction can reach when it does.
MicroVMs
413 Request Entity Too Large When You Already Raised the Limit
You raised the body size limit and the upload still fails. There are almost always two limits, and the one you changed is rarely the one rejecting you.
MicroVMs
The Service Is Running, Listening, and Completely Unreachable
curl works on the box and hangs from outside. Four places the packet can die, and how to tell which one killed it without guessing.
MicroVMs
The Domain Resolved Everywhere Except Where I Was Sitting
A CNAME that dig confirmed, a browser that refused, and a certificate stuck on pending. Three separate caches pretending to be one problem.
MicroVMs
Your Database Got Slower and Nothing in Your Code Changed
Query times doubling at unpredictable hours with no deploy and no traffic spike. When the cause is not in your process, it is usually not on your machine either.
MicroVMs
The Test That Only Failed When It Ran Second
A suite that passed alone and failed in the pipeline. The bug was not in the test, it was in what the previous job left behind on the runner.
Networking
Cloudflare Error 526 and the Redirect Loop: Two Failures, One Setting
Flexible gives you an infinite redirect. Full strict gives you a 526. The documentation says Full or higher, and higher is the one that breaks.
MicroVMs
I Rebooted the VM and the Kernel Did Not Change
A patched kernel that kept reporting the old version after every reboot. The reboot was working perfectly. My assumption about where the kernel comes from was wrong.