ytt (Carvel)

ytt (Carvel) is a YAML templating tool that allows users to create reusable and extensible configurations. It focuses on structure-oriented templating, using YAML documents as templates and enabling the setting of values and attaching statements like if and for loops directly on nodes. This approach enhances readability and simplifies structure reuse, avoiding common text insertion issues. ytt supports modularized configuration, allowing users to weave templating into their configurations, externalize values to variables, and extract repeated snippets into functions. It also enables patching on top of existing configurations using overlays for precise structural edits. ytt's deterministic execution environment ensures consistent outputs with the same inputs by restricting access to external resources like the filesystem, network, or operating system interfaces. It is designed for users who manage complex YAML configurations, such as Kubernetes configurations, Concourse pipelines, or Docker Compose files.