# YAML Language Prompt Snippet

## Key Concepts

- **Indentation-Based Nesting**: Whitespace-sensitive structure (spaces only, no tabs) defining hierarchy
- **Anchors and Aliases**: `&anchor` defines a reusable block, `*anchor` references it to avoid duplication
- **Merge Keys**: `<<: *anchor` merges anchor contents into the current mapping
- **Multi-Line Strings**: Literal block (`|`) preserves newlines, folded block (`>`) joins lines
- **Document Separators**: `---` starts a new document, `...` ends one (multi-document streams)
- **Tags and Types**: `!!str`, `!!int`, `!!bool` for explicit typing; custom tags for application-specific types
- **Flow Style**: Inline JSON-like syntax `{key: value}` and `[item1, item2]` for compact notation
- **Environment Variable Substitution**: `${VAR}` patterns used in docker-compose and CI configs

## Notable File Patterns

- `docker-compose.yml` / `docker-compose.yaml` — Multi-container Docker application definition
- `.github/workflows/*.yml` — GitHub Actions CI/CD workflow definitions
- `.gitlab-ci.yml` — GitLab CI/CD pipeline configuration
- `kubernetes/*.yaml` / `k8s/*.yaml` — Kubernetes resource manifests
- `*.config.yaml` — Application configuration files
- `mkdocs.yml` — MkDocs documentation site configuration
- `serverless.yml` — Serverless Framework configuration

## Edge Patterns

- YAML config files `configures` the code modules they control (e.g., database settings affect data layer)
- CI/CD YAML files `triggers` build and deployment pipelines
- docker-compose YAML `deploys` services and `depends_on` Dockerfiles
- Kubernetes YAML `deploys` and `provisions` application services

## Summary Style

> "Docker Compose configuration defining N services with networking, volumes, and health checks."
> "GitHub Actions workflow running tests on push and deploying to production on merge to main."
> "Kubernetes deployment manifest with N replicas, resource limits, and liveness probes."