<name> | GREEN text in angle brackets is a placeholder. Replace it (with the brackets) with your own value, e.g. <pod> becomes my-app-7d9f. |
--flag | BLUE text is an option / flag that changes how the command works. |
# comment | GREY text on the right explains what the command does. Do not type it. |
$ | The $ sign is the terminal prompt. Do not type it. Lines without $ are code snippets for a file (Jenkinsfile, YAML, HCL). |
No. | Tool | What you will find |
1 | AWS CLI | 48 commands - Manage every AWS service from the terminal - the base skill for any cloud DevOps role. |
2 | Linux | 51 commands - Daily-use commands for servers: files, processes, services, network and troubleshooting. |
3 | Jenkins | 30 commands - CI/CD automation server - service control, CLI, API calls and Jenkinsfile (pipeline) essentials. |
4 | Terraform | 40 commands - Infrastructure as Code - plan, apply, state management and safe production practices. |
5 | Ansible | 44 commands - Agentless configuration management - ad-hoc commands, playbooks, vault, roles and inventory. |
6 | Docker | 48 commands - Build, ship and run containers - images, containers, volumes, networks, compose and cleanup. |
7 | Kubernetes | 49 commands - Production edition: nodes, pods, rollouts, rollback, debugging and cluster health. |
8 | Helm | 36 commands - Kubernetes package manager - install, upgrade, rollback and test applications with charts. |
9 | OpenShift (oc) | 49 commands - Red Hat OpenShift CLI - projects, routes, builds, cluster operators, SCC and node debugging. |
10 | Azure CLI | 41 commands - Manage Azure resources - subscriptions, VMs, AKS, ACR, storage, Key Vault, RBAC and web apps. |
11 | Git | 54 commands - Daily Git workflow plus the recovery commands you need when something goes wrong. |
12 | Monitoring Tools | 38 commands - Prometheus, PromQL, Alertmanager, Grafana, Loki and Elasticsearch - the commands used in on-call. |
13 | Linux Observability | 49 commands - Find CPU, memory, disk, network and application bottlenecks on a live server - USE method. |
14 | Argo CD & GitOps | 34 commands - GitOps continuous delivery for Kubernetes - Git is the single source of truth. |
15 | HashiCorp Vault | 34 commands - Secrets management - store, rotate and audit secrets, dynamic credentials and backups. |
16 | DevSecOps Tools | 28 commands - Shift-left security - scan images, code, IaC, dependencies, secrets and sign artifacts in CI/CD. |
17 | GitHub Actions | 34 commands - CI/CD workflow syntax - triggers, jobs, secrets, OIDC to cloud, approvals and reusable patterns. |
18 | Kubernetes Power Tools | 38 commands - Ecosystem tools top companies use daily - k9s, stern, kubectx, Kustomize, Istio, cert-manager, Karpenter, KEDA. |
Production Golden Rules | • Always run 'aws sts get-caller-identity' BEFORE any change - confirm you are in the right account/role. | • Use '--dry-run' (EC2) and '--query' + '--output table' to preview and filter results safely. | • Never hard-code access keys. Use SSO / IAM roles / OIDC and rotate keys regularly. | • Take a snapshot (EBS / RDS) before any risky production change. |
Production Golden Rules | • 'df -h' shows free space but 'df -i' shows free inodes - a server can be 'full' with space left. | • Use 'kill -15' (graceful) first. Use 'kill -9' only as last resort - it can corrupt data. | • Always take a backup (cp -a / tar) before editing config files in /etc. | • Use 'journalctl -u <service>' first when a service fails - the reason is almost always there. |
Production Golden Rules | • Back up JENKINS_HOME (/var/lib/jenkins) regularly - it holds all jobs, credentials and config. | • Use 'safeRestart' (not 'restart') so running builds finish first. | • Never print secrets in logs - use credentials() / withCredentials() and keep 'mask passwords' on. | • Add an 'input' approval step and 'disableConcurrentBuilds()' for production deployments. |
Production Golden Rules | • ALWAYS run 'terraform plan -out=tfplan' and review it before 'apply tfplan'. | • Keep state in a remote backend (S3 + DynamoDB lock / Terraform Cloud) with versioning enabled. | • Use 'state pull > backup.tfstate' before any 'state mv/rm' operation. | • Use '-target' only for emergencies - it can leave your infrastructure out of sync. |
Production Golden Rules | • Always dry-run first: 'ansible-playbook site.yml --check --diff'. | • Use 'serial: 1' (rolling update) and 'max_fail_percentage' so one bad host does not take down production. | • Encrypt every secret with ansible-vault - never commit plain passwords to Git. | • Write idempotent tasks (use modules, not raw shell) so playbooks are safe to re-run. |
Production Golden Rules | • Never run containers as root - add 'USER appuser' in the Dockerfile and use a small base image. | • Always set '--restart unless-stopped' and memory/CPU limits for production containers. | • 'docker system prune -af --volumes' DELETES unused volumes (data!). Check before running. | • Pin image tags (nginx:1.27) - never use ':latest' in production. Scan images with Trivy. |
Production Golden Rules | • Rollback fast: 'kubectl rollout undo deployment/<name>' - the first thing to try after a bad release. | •CrashLoopBackOff? Use 'kubectl logs --previous <pod>' and 'kubectl describe pod <pod>' (check Events). | • Always 'cordon' + 'drain' a node before maintenance. Set PodDisruptionBudgets for critical apps. | • Use 'kubectl diff -f' and '--dry-run=server' before 'apply' in production. |
Production Golden Rules | • Use 'helm upgrade --install --atomic --timeout 10m' - it auto-rolls back if the release fails. | • Preview with 'helm diff upgrade' (plugin) or '--dry-run --debug' before touching production. | • Keep one values file per environment (values-dev.yaml, values-prod.yaml) in Git. | • Pin chart versions with '--version' so deployments are repeatable. |
Production Golden Rules | • After any upgrade check 'oc get clusteroperators' - all should be Available=True, Degraded=False. | • Use 'oc debug node/<node>' to troubleshoot nodes - no SSH needed. | • Run 'oc adm must-gather' and attach it to Red Hat support cases. | • Avoid 'anyuid' / 'privileged' SCC - give the least privilege that works. |
Production Golden Rules | • Check 'az account show' before every change - wrong subscription is the #1 Azure mistake. | • 'az group delete' removes EVERYTHING inside the group. Use resource locks on production. | • Use Managed Identity / Service Principal with least-privilege RBAC - not personal accounts in pipelines. | • Use deployment slots (staging -> swap) for zero-downtime web app releases. |
Production Golden Rules | • Never 'git push --force' on shared branches - use '--force-with-lease'. | • 'git reflog' can bring back 'lost' commits after a bad reset or rebase. | • Use 'git revert <sha>' to undo a commit on main (history stays clean and safe). | •Committed a secret? Rotate it immediately - then clean history with git filter-repo. |
Production Golden Rules | • Watch the 4 Golden Signals: Latency, Traffic, Errors, Saturation. | • Alert on symptoms users feel (error rate, latency) - not only on CPU / memory. | • Always validate config with 'promtool check config / rules' BEFORE reloading Prometheus. | • Add a '--comment' when creating silences so the next engineer knows why. |
Production Golden Rules | • USE method: for every resource check Utilization, Saturation and Errors. | • Load average higher than CPU cores = saturation. Check 'vmstat 1' column 'r' and 'wa'. | • Disk full but 'du' shows less? A deleted file is still open - find it with 'lsof +L1'. | • OOM kills? 'dmesg -T | grep -i oom' tells exactly which process was killed. |
Production Golden Rules | • Enable 'automated' sync with 'selfHeal' and 'prune' so manual cluster changes are reverted. | • Rollback by 'git revert' in the config repo - that is the real GitOps way. | • Use 'argocd app diff' before sync to see exactly what will change in prod. | • Use separate Projects (AppProject) to limit which repos / namespaces a team can deploy to. |
Production Golden Rules | • Take Raft snapshots regularly: 'vault operator raft snapshot save'. Test the restore. | • Enable an audit device on day one - you need it for every security investigation. | • Prefer dynamic (short-lived) credentials over static passwords. | • Leaked token? 'vault token revoke' or 'vault lease revoke -prefix <path>' immediately. |
Production Golden Rules | • Fail the pipeline on HIGH / CRITICAL findings: 'trivy image --exit-code 1 --severity HIGH,CRITICAL'. | • Scan at 3 points: source code (SAST / secrets), build (dependencies, images) and runtime (cluster). | • Generate an SBOM for every release and sign images with cosign. | • Use '--ignore-unfixed' to focus the team on vulnerabilities that actually have a fix. |
Production Golden Rules | • Use OIDC ('id-token: write') to assume cloud roles - no long-lived cloud keys in secrets. | • Pin third-party actions to a commit SHA and set minimal 'permissions'. | • Protect production with 'environment: production' + required reviewers (manual approval). | • Add 'concurrency' so two deployments never run at the same time. |
Production Golden Rules | • k9s + stern + kubectx/kubens save hours during an incident - install them on day one. | • Use Kustomize overlays (base + dev / prod) to avoid copy-pasting YAML. | • Expired certificate = outage. Always monitor cert-manager 'Certificate' objects. | • Use Karpenter / Cluster Autoscaler + KEDA to scale nodes and pods on real demand. |