SadServers Labs

Learn by Technology

Guides, troubleshooting tips, cheatsheets, and hands-on scenarios to level-up or start your DevOps / SRE career.

Linux & Bash

Bash

Shell, scripts, pipelines

Cron

Scheduled jobs, crontab, logs

Disk volumes

Mounts, LVM, fstab, space

DNS

Resolution, records, resolv.conf

SSH

Keys, sshd, scp, bastions

Supervisord

Process supervisor (legacy)

systemd

Units, services, timers, journal

Web Servers

Apache

httpd, vhosts, modules, logs

Caddy

Reverse proxy, TLS, Caddyfile

Nginx

Server blocks, proxy, upstreams

HAProxy

Load balancing, ACLs, health checks

Gunicorn

WSGI workers, Django, Flask

SSL / TLS

Certs, openssl, Let's Encrypt

Traefik

Dynamic proxy, Docker, K8s

Databases

ClickHouse

OLAP, merges, replication

Postgres

SQL, psql, locks, vacuum

MySQL

MariaDB, InnoDB, replication

SQLite

Embedded DB, WAL, Litestream

Redis

Cache, pub/sub, persistence, replication

MongoDB

Documents, replica sets, indexes

etcd

K8s state store, Raft, snapshots

Data Processing

Data processing

JSON, CSV, ETL, batch vs stream

Docker

Images, containers, Compose, networks

Podman

Daemonless, rootless, pods, Quadlet

Kubernetes

Pods, kubectl, RBAC, krew plugins

Helm

Charts, releases, values, rollback

CI/CD

Jenkins

Pipelines, agents, CI/CD automation

GitHub Actions

Workflows, runners, YAML pipelines

Infrastructure as Code

Ansible

Playbooks, inventory, roles, modules

Terraform

HCL, state, plan/apply, modules

Tooling / Applications

Git

Clone, branch, merge, remotes

FTP

vsftpd, PASV, legacy B2B feeds

RabbitMQ

RMQ, dashboard, queues, consumers

Envoy

Proxy, xDS, admin API, mesh

HashiCorp Vault

Secrets, seal/unseal, policies

Harbor

Registry, scan, replicate, RBAC

Prometheus

Metrics, PromQL, Grafana dashboards