DevOps, NGINX & Linux Troubleshooting in Production
Practical write-ups on real production issues — NGINX 502 bad gateway errors, Linux connection refused failures, Docker infrastructure debugging, and security operations. Every post is a real incident, fully documented.
What This Blog Covers
Written for engineers who are mid-incident, not mid-tutorial. Every post documents a real problem with the exact commands, configs, and reasoning behind the fix.
- ▸NGINX reverse proxy debugging — 502 errors, upstream timeouts, keepalive misconfiguration
- ▸Linux networking — TCP states, socket exhaustion, TIME_WAIT, sysctl tuning
- ▸Production incident response — log triage, root cause analysis, postmortems
- ▸Docker infrastructure — container networking, log rotation, resource limits
- ▸Security operations — SSL/TLS hardening, firewall rules, access log analysis
Common topics include diagnosing nginx 502 errors and connection refused failures caused by TIME_WAIT socket exhaustion, tuning Linux kernel parameters for high-traffic systems, and infrastructure debugging under production load.
About Damon
Senior DevOps and infrastructure engineer with a background in technical support on real-world production systems. That support background means I understand how things fail under load — not just how they look on architecture diagrams.
I've diagnosed NGINX upstream failures, traced Linux networking issues to kernel socket limits, and responded to security incidents across high-traffic infrastructure. This blog is where I document what actually worked.
Full background and experience →Featured Articles
In-depth guides on NGINX troubleshooting, Linux networking, and production debugging
NGINX 502 Bad Gateway Under Load: Causes, Debugging, and Fixes
Why NGINX returns 502 Bad Gateway only at high traffic — ephemeral port exhaustion, missing upstream keepalive, and proxy timeout misconfiguration. Includes step-by-step diagnosis commands and production-ready config fixes.
Read article →NGINX Upstream Keepalive Explained: Why Missing It Causes 502 Errors
Deep dive into TCP connection reuse in NGINX reverse proxying — HTTP/1.0 vs 1.1, TIME_WAIT buildup at scale, and the exact keepalive configuration that eliminates connection refused errors under load.
Read article →Linux TIME_WAIT: The Hidden Cause of ECONNREFUSED and Port Exhaustion
How Linux TIME_WAIT exhausts ephemeral ports and causes connection failures even when your application is healthy. Covers detection with ss and netstat, sysctl tuning, and why tcp_tw_recycle will break your server.
Read article →Browse by Topic
nginx troubleshooting · linux debugging · infrastructure · security operations
Latest Articles
Most recent posts on DevOps, Linux, NGINX, and production debugging
Linux TIME_WAIT Explained: Why It Causes Connection Failures and How to Fix It
Linux TIME_WAIT exhausts ephemeral ports and causes ECONNREFUSED under load — even when your app is healthy. Learn what TIME_WAIT is, how to detect port exhaustion with ss and netstat, and the exact sysctl fixes that resolve it.
NGINX Upstream Keepalive Explained: Why Missing It Causes 502 Errors
Missing keepalive in your NGINX upstream block silently kills connections under load. Here's exactly what keepalive does, how TCP connection reuse works, and the production-ready config that stops 502s before they start.
NGINX 502 Bad Gateway Under Load: Causes, Debugging, and Fixes
NGINX returning 502 Bad Gateway only under high load? This guide covers every root cause — ephemeral port exhaustion, missing keepalive, proxy timeouts, worker limits — with step-by-step debugging commands and production-ready config fixes.
Docker Ate My Disk: Fixing Log Rotation Before It Kills Production
How a single verbose container filled a 500GB disk in 72 hours, and the exact daemon.json config that stops it from ever happening again.
NGINX SSL Hardening: From C Grade to A+ on SSL Labs
A step-by-step walkthrough of the NGINX TLS configuration changes that take you from a mediocre SSL rating to a perfect score — without breaking compatibility.