OpenSSL is the most widely used toolkit for working with SSL/TLS certificates on Linux systems. On RHEL 9, it provides everything you need to generate private keys, create certificate signing requests (CSRs), sign certificates using your own certificate authority, and convert between certificate formats. Understanding OpenSSL is essential for any sysadmin managing secure services. This […]
Docker containers are ephemeral by default — all data written inside a container is lost when the container is removed. Docker provides two mechanisms for persisting data and sharing files between containers and the host: volumes (managed by Docker, stored in /var/lib/docker/volumes/) and bind mounts (map a host directory directly into a container). Volumes are […]
Podman is RHEL 9’s default container engine and, unlike Docker, runs entirely rootless and integrates natively with systemd. Socket activation is a systemd feature that lets the kernel hold a listening socket open while the service is stopped; the moment the first connection arrives, systemd starts the corresponding service and hands the socket over. This […]
cAdvisor (Container Advisor) is an open-source daemon from Google that collects, aggregates, and exposes resource usage and performance metrics for every running container on a host. Unlike Docker’s built-in docker stats, cAdvisor exposes its data in Prometheus format, making it a natural fit for scraping alongside Node Exporter. This tutorial covers running cAdvisor on RHEL […]
NetworkManager is the default network management service on RHEL 9, and it provides a powerful command-line tool called nmcli for configuring network interfaces. Assigning a static IP address is a common requirement for servers that need a predictable, stable address on the network. This tutorial walks through every method available on RHEL 9 to configure […]
Helm is the package manager for Kubernetes — it allows defining, installing, and upgrading complex Kubernetes applications using charts, which are pre-configured packages of Kubernetes resource manifests. Instead of manually writing and applying dozens of YAML files for a complex application (deployments, services, config maps, secrets, ingress rules, RBAC), a single helm install command deploys […]
Podman is Red Hat’s recommended Docker-compatible container engine that runs containers without requiring a root-owned daemon. Unlike Docker, which requires the Docker daemon (dockerd) running as root, Podman runs containers directly as the user executing the command — a model called rootless containers. This eliminates an entire class of privilege escalation vulnerabilities: even if a […]
Gitea is a lightweight, self-hosted Git service written in Go that provides GitHub-like functionality (repositories, issues, pull requests, wikis, webhooks, and CI/CD via Gitea Actions) in a single binary consuming under 100 MB of RAM. Compared to GitLab CE (which requires 4–8 GB RAM and a complex Omnibus bundle), Gitea is ideal for small teams, […]
VictoriaMetrics is a high-performance, open-source time-series database and monitoring solution that is fully compatible with the Prometheus query API. It offers significantly better data compression, faster ingestion rates, and lower memory consumption compared to Prometheus, making it an attractive choice for large or long-retention deployments. On RHEL 9 you can run VictoriaMetrics as a drop-in […]
PgBouncer is a lightweight PostgreSQL connection pooler that solves one of PostgreSQL’s most common scalability problems: the high cost of creating new database connections. Unlike MySQL, PostgreSQL spawns a new OS process for each client connection, which consumes approximately 5–10 MB of memory and requires significant CPU time to establish. Web applications that open hundreds […]
