AWS Documentation
The official AWS docs — always the ground truth for services like EC2, EKS, RDS, WAF, and over 200+ services. Bookmark the Architecture Center too.
Kubernetes Official Documentation
Complete Kubernetes docs covering concepts, API reference, tasks, and tutorials. The Concepts section is essential reading for anyone running k8s in production.
The Phoenix Project
A novel about DevOps transformation — follows an IT manager fixing a failing project. Changes how you think about work, flow, and feedback loops. Must-read.
Terraform: Up & Running (3rd Ed.)
The definitive guide to Terraform by Yevgeniy Brikman. Covers modules, state management, testing, and running Terraform in teams. Highly practical.
Linux Command Line Cheatsheet
A comprehensive reference for Linux commands — file operations, networking, process management, grep, awk, sed. Essential for any DevOps engineer daily.
Docker Official Documentation
Complete Docker docs — from basics to advanced topics like multi-stage builds, Docker Compose, networking, volumes, and the Docker daemon internals.
Prometheus & Grafana for Beginners — KodeKloud
Hands-on course covering Prometheus architecture, PromQL queries, recording rules, alerts, and building production-grade Grafana dashboards.
GitHub Actions Documentation
Official docs for GitHub Actions — workflow syntax, reusable workflows, secrets management, self-hosted runners, and CI/CD best practices.
CKA Exam Prep — Kubernetes The Hard Way
Kelsey Hightower's famous guide to bootstrapping Kubernetes from scratch. Understanding this deeply prepares you for the CKA and makes k8s concepts click.
OWASP Top Ten
The most critical web application security risks — essential reading for anyone doing DevSecOps, setting up WAF rules, or code-reviewing applications.
Bash Scripting Cheatsheet
Quick reference for Bash scripting — variables, loops, conditionals, functions, arrays, string manipulation, and common patterns for automation scripts.
Google SRE Book (Free)
Google's Site Reliability Engineering book — covers error budgets, SLOs/SLAs, production readiness reviews, postmortems, and on-call practices. Free online.