DevOps and cloud cheat sheet

1. 1Linux, the shell and scriptingAlmost every server, container and pipeline runner is Linux. These are the commands and ideas you use daily.8 concepts

   1. 1File permissionsEach file has an owner, a group and read, write and execute bits for owner, group and others.
   2. 2Users, groups and sudoLinux runs everything as some user.
   3. 3Processes and signalsA process is a running program with a PID.
   4. 4systemd servicessystemd is the init system on most distributions.
   5. 5System logssystemd collects service output in the journal, read with journalctl.
   6. 6Pipes, grep, sed and awkA pipe | sends one command's output into the next.
   7. 7Safe Bash scriptsA Bash script is a file of commands with a shebang line.
   8. 8cron and systemd timerscron runs commands on a schedule written as five fields: minute, hour, day of month, month, day of week. systemd timers do the same with logging and dependency…

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2. 2Git workflowsEverything in DevOps, from app code to infrastructure and pipeline definitions, lives in Git and changes through reviewed commits.6 concepts

   1. 1Branches and pull requestsA branch is a movable pointer to a line of commits.
   2. 2Merge vs rebasegit merge joins histories with a merge commit.
   3. 3Trunk-based developmentEveryone merges small changes into one main branch at least daily, hiding unfinished work behind feature flags.
   4. 4Undoing changes: revert vs resetgit revert adds a new commit that undoes an earlier one.
   5. 5Tags and semantic versioningA tag names a specific commit, such as v2.4.1.
   6. 6.gitignore and secrets in Git.gitignore lists files Git should not track, such as .env, build output and Terraform state.

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3. Networking for engineersHow traffic finds your servers and what to check when it does not. Most outages that look like app bugs are DNS, ports, firewalls or certificates.8 conceptsOpens with credits
4. Containers with DockerPackage an app with everything it needs so it runs the same on a laptop, in CI and in production.9 conceptsOpens with credits
5. Cloud on AWS: the core servicesThe AWS services nearly every workload uses. The ideas carry over to Azure and Google Cloud under different names.11 conceptsOpens with credits
6. Infrastructure as code with TerraformDescribe infrastructure in versioned files, review changes as plans, and rebuild environments the same way every time.6 conceptsOpens with credits
7. CI/CD pipelinesAutomate the path from a commit to production so every change is built, tested and deployed the same way.7 conceptsOpens with credits
8. Kubernetes and GitOpsRun containers across a cluster of machines with self-healing, scaling and rollouts, and keep the cluster in sync with Git.10 conceptsOpens with credits
9. Observability and incident responseSee what production is doing, get paged only for what matters, and learn from every incident.8 conceptsOpens with credits
10. Security basicsThe habits that prevent most real-world breaches in cloud and DevOps work.6 conceptsOpens with credits
11. 11Glossary, A to ZEvery concept in the sheet and the smaller terms it uses, in one list.221 terms

Linux, Docker, Kubernetes, AWS.