web server

Common Problems 120029

Debian 12: Nginx returns 502 to upstream app

🟠 High   ⏱ 5–30 min  Last verified: 23 October 2023 Affected versions: Debian 12 📖 ~1 min read Table of contents Symptom & Impact Environment & Reproduction Root Cause Analysis Quick Triage Step-by-Step Diagnosis Solution – Primary Fix Solution – Alternative Approaches Verification & Acceptance Criteria Rollback Plan Prevention & Hardening Related Errors & […]

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How to Configure Apache as a Reverse Proxy on CentOS Stream 9 — step-by-step CentOS Stream 9 tutorial on Progressive Robot

How to Configure Apache as a Reverse Proxy on CentOS Stream 9

Introduction This tutorial demonstrates how to Configure Apache as a Reverse Proxy on CentOS Stream 9 on CentOS Stream 9. It is written for administrators who want a repeatable, well-explained walkthrough that goes beyond a bare command list and explains each configuration choice. Every command is tested against a freshly registered CentOS Stream 9 system […]

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How to Configure Apache with mod_security on CentOS Stream 9 — step-by-step CentOS Stream 9 tutorial on Progressive Robot

How to Configure Apache with mod_security on CentOS Stream 9

Introduction How to Configure Apache with mod_security on CentOS Stream 9 on CentOS Stream 9 provides administrators with a robust, enterprise-ready workflow that integrates cleanly with systemd, SELinux, firewalld, and the modern AppStream module system. In this tutorial we will walk through every step required, from package installation to verification, so that the resulting configuration […]

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How to Deploy a Ruby on Rails Application on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Deploy a Ruby on Rails Application on RHEL 9

Ruby on Rails (Rails) is a full-stack web application framework built on Ruby that made convention-over-configuration and the MVC pattern mainstream in web development. Rails provides ActiveRecord (ORM), ActionController (routing and controllers), ActionView (templating with ERB/Haml), ActionMailer, ActiveJob (background jobs), ActionCable (WebSockets), and a comprehensive set of security defaults out of the box. A Rails […]

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How to Configure Apache with mod_pagespeed on Oracle Linux 9 — step-by-step Oracle Linux 9 tutorial on Progressive Robot

How to Configure Apache with mod_pagespeed on Oracle Linux 9

Introduction Oracle Linux 9 ships with a stable, security-hardened base that makes deploying configure apache with mod_pagespeed on oracle linux 9 both straightforward and auditable. This tutorial covers the complete procedure for how to Configure Apache with mod_pagespeed on Oracle Linux 9, including dnf module streams where applicable, systemd unit management, and the firewalld rules […]

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How to Configure Rate Limiting in Nginx on Debian 12 — step-by-step Debian 12 tutorial on Progressive Robot

How to Configure Rate Limiting in Nginx on Debian 12

Introduction This guide explains how to Configure Rate Limiting in Nginx on Debian 12 on Debian 12 Bookworm. Debian Bookworm uses systemd for service management, nftables as the underlying packet filter (with ufw or iptables front-ends still available), and AppArmor for mandatory access control. Every command is designed for a minimal Debian 12 install with […]

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How to Secure Apache with Let's Encrypt on CentOS Stream 9 — step-by-step CentOS Stream 9 tutorial on Progressive Robot

How to Secure Apache with Let’s Encrypt on CentOS Stream 9

Introduction This tutorial demonstrates how to Secure Apache with Let’s Encrypt on CentOS Stream 9 on CentOS Stream 9. It is written for administrators who want a repeatable, well-explained walkthrough that goes beyond a bare command list and explains each configuration choice. Every command is tested against a freshly registered CentOS Stream 9 system with […]

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How to Set Up a Highly Available Web Stack with Keepalived on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Set Up a Highly Available Web Stack with Keepalived on RHEL 9

Keepalived implements the Virtual Router Redundancy Protocol (VRRP) on Linux, allowing two or more servers to share a single virtual IP address (VIP). If the master server fails, the backup server automatically claims the VIP within seconds, providing high availability with no changes required on clients or DNS. On RHEL 9, Keepalived integrates cleanly with […]

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Common Problems 120125

Debian 12 NGINX 502 Bad Gateway with PHP-FPM

🟠 High   ⏱ 5–30 min  Last verified: 26 September 2023 Affected versions: Debian 12 📖 ~1 min read Table of contents Symptom & Impact Environment & Reproduction Root Cause Analysis Quick Triage Step-by-Step Diagnosis Solution – Primary Fix Solution – Alternative Approaches Verification & Acceptance Criteria Rollback Plan Prevention & Hardening Related Errors & […]

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How to Set Up WordPress with Nginx on Debian 12 — step-by-step Debian 12 tutorial on Progressive Robot

How to Set Up WordPress with Nginx on Debian 12

Introduction This guide explains how to Set Up WordPress with Nginx on Debian 12 on Debian 12 Bookworm. Debian Bookworm uses systemd for service management, nftables as the underlying packet filter (with ufw or iptables front-ends still available), and AppArmor for mandatory access control. Every command is designed for a minimal Debian 12 install with […]

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