Systemd is the init system and service manager for RHEL 9 — it is PID 1, the parent of every other process on the system. Understanding how to manage systemd services is foundational to every other administrative task: installing Nginx means enabling the nginx service; configuring a database means understanding its unit file; debugging a […]
A single Redis instance has two failure modes: if the server goes down, all cached data is lost and every request hits the origin database; and if the dataset grows beyond a single server’s RAM, there’s no built-in way to distribute it. Redis provides two solutions: Redis Sentinel for high availability (automatic failover with a […]
Apache Kafka is a distributed event streaming platform designed for high-throughput, fault-tolerant, and replayable message streams. Unlike traditional message brokers, Kafka persists messages to disk in ordered, append-only topic logs and retains them for a configurable period (days or weeks). Consumers read messages at their own pace using consumer offsets, and any consumer can re-read […]
Accurate time synchronization is not optional on a server — it is a hard requirement. TLS certificate validation fails when the clock is wrong by more than a few minutes. Kerberos authentication rejects tickets with a clock skew over 5 minutes. Cron jobs fire at the wrong time. Log correlation across multiple servers becomes impossible […]
Rust is a systems programming language focused on memory safety, performance, and concurrency. Rust achieves memory safety without a garbage collector through its ownership and borrowing system, which enforces at compile time that there are no dangling pointers, buffer overflows, or data races. This makes Rust suitable for building high-performance systems software where both safety […]
PHP-FPM (FastCGI Process Manager) is the recommended way to run PHP behind a web server. Unlike the older Apache mod_php, which embeds a PHP interpreter in each Apache worker process, PHP-FPM runs as a separate service that manages a pool of PHP worker processes. Nginx communicates with PHP-FPM via a Unix socket or TCP socket […]
Postfix is a high-performance, open-source Mail Transfer Agent (MTA) that handles the sending and receiving of email over SMTP. It is the default MTA on many Linux distributions and integrates cleanly with the rest of the RHEL 9 mail stack, including Dovecot for IMAP delivery and OpenDKIM for email authentication. This tutorial covers installing Postfix, […]
Docker Compose transforms multi-container application deployment from a series of manual docker run commands into a declarative, version-controlled configuration. A production-ready Compose deployment includes health checks (to ensure services are truly ready before dependent services start), resource limits (to prevent runaway containers from consuming all host resources), restart policies (to automatically recover from failures), and […]
IPv6 adoption continues to accelerate as IPv4 address space is exhausted, and most production servers now need to serve traffic over both protocols simultaneously. RHEL 9 supports dual-stack networking natively through NetworkManager, allowing IPv4 and IPv6 addresses to coexist on the same interface without additional kernel modules. Configuring dual-stack correctly involves not only assigning addresses […]
HashiCorp Vault is an open-source secrets management platform that provides secure storage, access control, and auditing for sensitive data such as API keys, passwords, certificates, and encryption keys. Instead of hardcoding secrets in application configs or environment variables, applications request them from Vault at runtime using short-lived tokens or AppRole credentials. This tutorial covers installing […]
