Customizing Clusters and Plans with ytt Overlays

This topic explains how you can use ytt Overlays to customize Tanzu Kubernetes (workload) clusters and cluster plans.

Tanzu Kubernetes Grid distributes configuration files for clusters and cluster plans in the ~/.config/tanzu/tkg/providers/ directory.

You can customize these configurations by adding or modifying configuration files directly, or by using ytt overlays.

Directly customizing configuration files is simpler, but if you are comfortable with ytt overlays, they let you customize configurations at different scopes and manage multiple, modular configuration files, without destructively editing upstream and inherited configuration values.

For more information about ytt, including overlay examples and an interactive validator tool, see:

Clusters and Cluster Plans

The ~/.config/tanzu/tkg/providers/ directory includes ytt directories and overlay.yaml files at different levels, which lets you scope configuration settings at each level:

  • Provider- and version-specific ytt directories. For example, ~/.config/tanzu/tkg/providers/infrastructure-aws/v0.6.4/ytt.
    • Specific configurations for provider API version.
    • The base-template.yaml file contains all-caps placeholders such as "${CLUSTER_NAME}" and should not be edited.
    • The overlay.yaml file is tailored to overlay values into base-template.yaml.
  • Provider-wide ytt directories. For example, ~/.config/tanzu/tkg/providers/infrastructure-aws/ytt.
    • Provider-wide configurations that apply to all versions.
  • Top-level ytt directory, ~/.config/tanzu/tkg/providers/ytt.
    • Cross-provider configurations.
    • Organized into numbered directories, and processed in number order.
    • ytt traverses directories in alphabetical order and overwrites duplicate settings, so you can create a /04_user_customizations subdirectory for configurations that take precedence over any in lower-numbered ytt subdirectories.

IMPORTANT: You can only use ytt overlays to modify workload clusters. Using ytt overlays to modify management clusters is not supported.

Cluster and Plan Examples

Examples of ytt overlays for customizing workload clusters and cluster plans include:

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