Learn DevOps by Doing
Not Just Reading
Master Docker, Kubernetes, CI/CD, Terraform and more with hands-on tutorials and interactive browser playgrounds. Follow structured roadmaps to become a DevOps Engineer.
Real commands. Safe sandbox. No install, no sign-up.
Start Your DevOps Journey
Hand-picked tutorials to help you master essential DevOps tools and practices. From beginner to advanced levels.
Docker Fundamentals
Learn containerization from scratch. Build, ship, and run applications in containers.
Kubernetes Essentials
Master container orchestration with K8s. Deploy and manage containerized applications.
CI/CD with GitLab
Automate your deployment pipeline. Build, test, and deploy with confidence.
Terraform Basics
Infrastructure as Code made easy. Provision and manage cloud resources declaratively.
AWS for DevOps
Deploy applications on AWS. Learn EC2, S3, RDS, and essential AWS services.
Practice in a Real Terminal, Not a Video
Practice real commands in safe, full-screen browser labs, no install, no sign-up, nothing to break. Each lab guides you step by step from beginner to advanced and checks your work as you type.
Docker
Pull images, run and inspect containers, read logs and clean up: the full Docker workflow, hands-on.
Kubernetes
Run pods, create deployments and services, scale and roll out updates with kubectl in a simulated cluster.
Terraform
Write HCL, run plan and apply, and manage state as you provision simulated infrastructure.
Linux & Bash
Navigate the filesystem, manage permissions and processes, and sharpen your shell skills.
Structured Learning Paths
Follow our comprehensive roadmaps designed by industry experts. Get a clear path from beginner to professional.
DevOps Engineer
Complete roadmap from beginner to professional DevOps engineer.
What you'll learn
Cloud Engineer
Master cloud platforms (AWS, Azure, GCP) and become a certified cloud professional.
What you'll learn
Site Reliability Engineering
Learn to build and maintain highly reliable, scalable systems at enterprise level.
What you'll learn
164 Questions With Worked Answers
Sorted by seniority, because the same question is asked differently of a junior and a senior. Every answer is written out in full, with the follow-up the interviewer asks next.
Docker
28 QsImages, Fundamentals, Production and more.
Start revising →Kubernetes
30 QsWorkloads, Fundamentals, Networking and more.
Start revising →AWS
29 QsNetworking, IAM, Storage and more.
Start revising →Terraform
25 QsState, Workflow, Fundamentals and more.
Start revising →Linux
26 QsFilesystem, Processes, Shell and more.
Start revising →Git
26 QsFundamentals, History, Remote and more.
Start revising →Something Broken? Start Here
81 errors you will meet in real work, each one leading with the commands that fix it. The explanation is underneath, for when the system is back up.
CrashLoopBackOff
Your container starts, exits, and Kubernetes restarts it with growing delay. How to find which of the six causes is responsible, in order of likelihood.
Read the fix →ImagePullBackOff and ErrImagePull
Kubernetes cannot pull your container image. The events name the exact reason. Here is how to read them and fix each of the five causes.
Read the fix →OOMKilled (Exit Code 137)
The kernel killed your container for exceeding its memory limit. Why the application logged nothing, how to tell a leak from a bad limit, and the JVM trap.
Read the fix →Cannot connect to the Docker daemon
The Docker CLI cannot reach the daemon. Six causes. Daemon not running, group membership, wrong context, Desktop not started, WSL integration, CI without a daemon.
Read the fix →exec format error
Your container image was built for a different CPU architecture, usually arm64 on Apple Silicon running on amd64 servers. How to confirm it and build multi-arch.
Read the fix →Service has no endpoints
Your Kubernetes Service accepts connections and forwards them nowhere. There are exactly two causes: a selector that matches nothing, or Pods that are not Ready.
Read the fix →Terraform. Error acquiring the state lock
Terraform will not run because the state is locked. When force-unlock is safe, when it will corrupt your state, and how to stop it recurring.
Read the fix →git: Permission denied (publickey)
SSH is refusing your key before Git is involved at all. How to prove which key is offered, fix the four causes, and stop it recurring.
Read the fix →Free Cheatsheets & Tools
Quick-reference cheatsheets and browser-based tools, free with no sign-up required.
Docker
CheatsheetKubernetes
CheatsheetTerraform
CheatsheetLinux
CheatsheetGit
CheatsheetKubernetes YAML Generator
Free ToolDockerfile Linter
Free ToolYAML Validator
Free ToolCron Parser
Free ToolRegex Tester
Free ToolWant even more resources?
View All Tools & CheatsheetsReady to Become a
DevOps Professional?
Join thousands of learners who have transformed their careers with our comprehensive DevOps tutorials and roadmaps. Start learning today.