Networking
Your Timeouts Are Wrong and Here Is How to Set Them
A missing timeout turns a slow dependency into an outage. A badly chosen one turns a blip into a retry storm. Both are common.
Performance
Where Serverless Cold Start Time Actually Goes
Everyone blames the platform. Most of a cold start is usually your own initialisation code, and you can measure exactly which part.
Networking
502 Bad Gateway From Nginx: Which Side Is Actually Broken
The proxy is telling you your application failed. Here is how to read the error log line and identify which of six things went wrong.
Docker
Permission Denied in a Container When the File Is Right There
Non root containers break in predictable ways. Here is how UID mapping, volume ownership, and read only filesystems produce the same error.
Docker
Docker Build Works Locally and Fails in CI: The Eight Causes
Same Dockerfile, same repo, different result. The difference is nearly always cache, context, architecture, or something on your machine that is not in the image.
Node.js
EADDRINUSE: Finding and Killing Whatever Took Your Port
Address already in use. Here is how to find the process, why it sometimes is not a process at all, and why the port stays busy after you kill it.
AI
Running AI Agent Generated Code Safely: What Actually Contains It
If an agent can run shell commands, you have an arbitrary code execution problem. Here is what each isolation option genuinely protects against.
Networking
x509: certificate signed by unknown authority
Your browser trusts the certificate and your application does not. They use different trust stores, and inside a container there may not be one at all.
Docker
Debugging a Container With No Shell, No curl, and No ps
Distroless and scratch images are great for security and miserable when something breaks. Here is how to investigate a container that ships nothing.
DevOps
Your CI Cache Is Making Builds Slower and Occasionally Wrong
A cache with the wrong key restores nothing and uploads everything. A cache with too broad a key restores stale artifacts. Both are common.
Networking
Your Cache-Control Header Is Probably Wrong
no-cache does not mean do not cache. max-age on a CDN is not what you think. Here is what each directive actually does.
Docker
Containers Share a Kernel and That Is the Whole Story
The difference between a container and a microVM is one sentence long, and almost every isolation decision follows from it.