Glossary

Quick definitions, A to Z. Terms point to the guide that explains them in context.

Agent — software that watches the repo and applies desired state. ArgoCD, Flux, ansible-pull, a cron job. See The GitOps Loop.

ArgoCD — widely used Kubernetes GitOps agent with a web UI.

Base + overlay — shared configuration plus per-environment differences. See Common Patterns.

Break-glass — documented emergency procedure for intervening by hand when automation is the problem.

CI — continuous integration: automated checks (tests, lint) run on proposed changes.

Declarative — describing the desired end state, not the steps to get there. See Core Principles.

Desired state — how the system should look, as stored in git. The thing everything converges toward.

Drift — reality differing from desired state. Found by reconciliation.

Dry run — previewing what the automation would change, without changing anything (ansible --check, terraform plan).

Flux — Kubernetes GitOps agent, CLI-driven. Alternative to ArgoCD.

Infrastructure as code (IaC) — managing infrastructure with versioned files. Adjacent to GitOps; Terraform is IaC, not GitOps by itself.

Kustomize — Kubernetes-native way to do base + overlays.

Manifest — a file describing desired state (usually YAML in Kubernetes land).

OpenTofu — open-source Terraform fork.

Operator — a Kubernetes agent encoding operational knowledge; often managed via GitOps, not the same thing.

Promotion — moving a tested change from one environment to the next (dev → staging → prod).

Pull model — agents inside the environment fetch and apply state. The GitOps default.

Push model — an outside pipeline pushes changes into the environment. Simpler; no built-in reconciliation.

Reconciliation — the continuous compare-and-correct loop between desired and actual state. See Core Principles.

Sealed Secrets — encrypted Kubernetes secrets safe to store in git.

SOPS — file encryption for secrets in git, decrypted at apply time.

Sync — one application of desired state to the environment.

Terraform — declarative cloud infrastructure tool (push-based).