| IDP | Internal Developer Platform — the sum of all tools, conventions, and workflows that allow engineers to self-serve infrastructure |
| Golden Path | A pre-approved, convention-compliant pathway for a common workflow, encoded as a Backstage Scaffolder template |
| Domain | An ownership boundary in the catalog. Maps to a Backstage Domain entity, an ArgoCD AppProject, and a {domain}-gitops repository |
| System | A logical product grouping within a domain. Contains one or more services (Components) |
| Component | A single deployable unit — service, worker, frontend, cronjob — within a system |
| Resource | A cloud infrastructure asset (database, cluster, queue) that a Component depends on |
| Claim (XRC) | A Crossplane Composite Resource Claim — a Kubernetes object that declares desired cloud infrastructure |
| XRD | Crossplane Composite Resource Definition — defines the API for a resource type (e.g. GKECluster) |
| Composition | A Crossplane resource that implements an XRD for a specific cloud provider |
| ApplicationSet | An ArgoCD resource that generates multiple Applications from a template and generator |
| App of Apps | A single ArgoCD Application that manages all other Applications and ApplicationSets |
| Infra namespace | A Kubernetes namespace ({domain}-{env}-infra) dedicated to Crossplane Claims, separate from app namespaces |
| Sealed Secret | A Kubernetes Secret encrypted with the cluster's public key — safe to commit to Git |
| Reflector | A Kubernetes operator that mirrors Secrets and ConfigMaps across namespaces |
| Sync wave | An ArgoCD ordering mechanism that controls which resources are applied first within a sync operation |
| DORA metrics | Four key DevOps performance indicators: deployment frequency, lead time for changes, change failure rate, and MTTR |
| GitOps | Operational model where Git is the single source of truth for deployed state, with automated reconciliation |