A 504 Gateway Timeout means the proxy or gateway did not get a response from the upstream fast enough. In practical terms, a frontend server such as Nginx waited for Apache, PHP-FPM, Gunicorn, Node.js, or some internal API, and the answer took longer than the configured limit. I treat 504 as a timing problem with […]
HTTP 504 Gateway Timeout: Nginx and Apache Debugging That Finds the Real Bottleneck Read Post »
A 503 Service Unavailable response tells me the server is reachable, but it cannot handle the request right now. That wording matters. Unlike a DNS failure or connection refusal, the system is still present enough to answer. It is simply overloaded, deliberately unavailable, or temporarily unable to hand work to the component that should process
HTTP 503 Service Unavailable: Causes, Fixes, and the Checks I Rely On Read Post »
UFW (Uncomplicated Firewall) is the default firewall management tool on Ubuntu. It’s a frontend to iptables that makes common firewall tasks manageable without having to write iptables rules directly. I use it on most of my Ubuntu servers — it handles the 95% case well and doesn’t get in the way. Installation and Initial State
UFW Firewall on Ubuntu: Setup and Daily Use Read Post »
Certificate expiry is one of those problems that feels embarrassing when it happens. Every time I read about a major site going down because of an expired certificate, I think about how preventable it is. The certificate was always going to expire on a known date. The notification system failed, not the certificate. This guide
SSL Certificate Monitoring and Expiry Alerting: Never Let a Cert Expire Again Read Post »
If you’ve ever tried to install an SSL certificate and hit a wall because the server expects .crt but your CA sent you .pem, you know how frustrating this rabbit hole can get. I’ve been there more times than I’d like to admit. The good news is that once you understand what these formats actually
SSL Certificate Formats Explained: PEM, DER, PFX, CRT and More Read Post »
A 502 Bad Gateway error usually means Nginx was able to accept the client request, but it failed when it tried to talk to the upstream application that should have generated the real response. In practice, that upstream might be PHP-FPM, Apache, Gunicorn, uWSGI, Node.js, a local API on another port, or even another reverse
HTTP 502 Bad Gateway in Nginx: How I Troubleshoot It Without Guessing Read Post »
Redirects look simple until they are not. I have seen one misplaced 301 break a migration plan for days because browsers cached it so aggressively that testers kept insisting the “old bug” was still there after the config had already changed. I have also seen 302 used for a permanent site move, which delayed search
Redis is one of those services that starts as a simple cache and ends up being a critical piece of infrastructure. I’ve used it for session storage, rate limiting, job queues, pub/sub, and as a general-purpose key-value store. Getting the configuration right from the start saves headaches later. Installation For the latest stable version from
Redis on Linux: Installation, Configuration, and Production Tuning Read Post »
Most SSL guides focus on Nginx and Apache. But if you’re running HAProxy for load balancing, Caddy for automatic HTTPS, or Lighttpd on an embedded system, the configuration is different enough to warrant its own guide. I’ve set up SSL on all of these and the differences matter. HAProxy: SSL Termination at the Load Balancer
SSL Certificates for HAProxy, Caddy, and Other Web Servers Read Post »
A 403 Forbidden response means the server understood the request but is refusing to allow it. That sounds straightforward, but the cause can sit in three very different layers: the web server configuration, the Linux filesystem permissions, or the application itself. That layered view matters because 403 is one of the easiest errors to “fix”
HTTP 403 Forbidden in Nginx and Apache: The Permission Checks I Actually Use Read Post »