CI/CD Explained

Plain-English answers to "what is…" questions about CI/CD.

Beginner-friendly explainer articles on continuous integration and delivery: what CI/CD is, how pipelines, runners, and GitHub Actions work, and the concepts behind fast, reliable, cost-efficient automation.

CI/CD basics

What CI/CD, pipelines, and automation are.

CI serverWhat is a CI server? Learn what a continuous integration server does, how it coordinates builds and runners, CI/CD pipelineWhat is a CI/CD pipeline? Learn the stages a change passes through, how they connect, an example pipeline, Continuous integrationWhat is continuous integration? A plain-English explainer covering what CI is, how it works, a worked

Runners explained

Hosted, self-hosted, managed, and ephemeral runners.

What ephemeral runners areWhat an ephemeral CI runner is, how just-in-time registration works, and what changes about caching, secrets

Reliability explained

Flaky tests, transient failures, self-healing CI.

Making a pipeline reliableThe metrics that tell you whether CI is trustworthy, why pass rate is the wrong headline number, and the What self-healing CI isWhat self-healing CI actually does, the difference between explaining a failure, proposing a fix and What is a rate limit error?A rate limit error means a service is rejecting requests because you sent too many too fast.

Core concepts

Containers, caching, artifacts, OIDC, and more.

CI security for GitHub ActionsThe GitHub Actions security controls that actually reduce exposure: token permissions, pinning actions, the What is a multi-stage build?A multi-stage build uses several FROM stages so build tools stay out of the final image. What is a post-deployment check?A post-deployment check verifies that a release is healthy after it goes live, catching bad deploys quickly. What is a shebang line?A shebang line is the first line of a script that tells the OS which interpreter to run it with. What is a tmpfs?A tmpfs is a filesystem that lives in memory rather than on disk.

Tools explained

npm, Docker, Jest, Terraform, and the rest of the toolchain.

How Docker is put togetherThe pieces behind the docker command: the CLI, the daemon, containerd, runc, the image layers and the kernel Webpack explainedWebpack explained: how the JavaScript module bundler builds a dependency graph, loaders and plugins, a config Where Docker stores imagesThe real on-disk location of Docker images on Linux, macOS and Windows, why the directory is unreadable by

Git & version control

Commits, branches, merges, and pull requests.

Merge queueWhat is a merge queue? Learn how it serializes pull-request merges, tests each against the latest main, and git stashWhat is git stash? An explainer on temporarily shelving uncommitted changes to switch context, how to restore

Explore other topics

GitHub ActionsWorkflow, runner, and YAML errors - diagnosed and fixed. Node.js & npmnpm, yarn, and pnpm failures in CI - solved. DockerBuild, run, compose, and registry errors - explained. Pythonpip, poetry, venv, and pytest failures - fixed. Java & JVMMaven, Gradle, and JVM failures in CI - resolved. GoGo build, module, and test failures - diagnosed.