ResourceTemplate

In order to make customizations easier, Koreo provides ResourceTemplate. ResourceTemplate allows static resources to be defined which ResourceFunctions may then overlay with dynamic values to produce a fully materialized resource. ResourceFunctions can dynamically compute the ResourceTemplate name, making it easy to support a range of use cases and configurations for a managed resource. By allowing the statically defined resource to be dynamically loaded, it reduces the need to create complex or verbose Functions.

For instance, ResourceTemplates may be provided for different environments, for specific resource types, or dynamically supplied configuration values. ResourceTemplates are also useful for simple static templates to provide common configuration, such as regions. This allows the ResourceFunction to be responsible for defining the interface and applying the values while ResourceTemplates supply the bulk of static configuration.

This model makes it easy to turn existing resources into ResourceTemplates, then use a Function only to apply dynamic values.

Static Resource Specification

The template is a static Target Resource Specification. Both apiVersion and kind must be provided, but everything else is optional. This static template will be (optionally) overlaid within the ResourceFunction. The metadata.name and metadata.namespace properties are always overlaid by the ResourceFunction, so you need not specify them.

ResourceTemplate Example

The example below demonstrates a ResourceFunction which dynamically loads a ResourceTemplate based on a provided input along with a corresponding FunctionTest.

ResourceTemplate 1

apiVersion: koreo.dev/v1beta1
kind: ResourceTemplate
metadata:
  # The template will be looked up by its name.
  name: docs-template-one.v1
  namespace: koreo-demo
spec:
  # Template contains the static resource that will be used as the base.
  # apiVersion and kind are required. The template is the actual body, or some
  # portion thereof, which you'd like to set static values for.
  template:
    apiVersion: koreo.dev/v1beta1
    kind: TestDummy
    metadata:
      labels:
        docs.koreo.dev/example: template-label
    spec:
      value: one
      nested:
      - 1
      - 2

ResourceTemplate 2

apiVersion: koreo.dev/v1beta1
kind: ResourceTemplate
metadata:
  name: docs-template-two.v1
  namespace: koreo-demo
spec:
  template:
    apiVersion: koreo.dev/v1beta1
    kind: TestDummy
    metadata:
      labels:
        docs.koreo.dev/example: template-label
      annotations:
        docs.koreo.dev/example: template-two
    spec:
      value: two
      structure:
      - name: doc
      - name: examples

ResourceFunction

apiVersion: koreo.dev/v1beta1
kind: ResourceFunction
metadata:
  name: docs-template-function.v1
  namespace: koreo-demo
spec:
  locals:
    template_name: ="docs-template-" + inputs.template + ".v1"

  apiConfig:
    apiVersion: koreo.dev/v1beta1
    kind: TestDummy
    plural: testdummies

    name: =inputs.metadata.name + "-template-docs"
    namespace: =inputs.metadata.namespace

  resourceTemplateRef:
    name: =locals.template_name

  overlays:
  - overlay:
      metadata: =resource.metadata.overlay(inputs.metadata)
      spec:
        value: =inputs.value
        addedProperty: =inputs.value * 17

FunctionTest

apiVersion: koreo.dev/v1beta1
kind: FunctionTest
metadata:
  name: docs-template-function.v1
  namespace: koreo-demo
spec:
  functionRef:
    kind: ResourceFunction
    name: docs-template-function.v1

  # Template 'one' will be the base case.
  inputs:
    template: one
    value: 42
    metadata:
      name: test-demo
      namespace: tests
      labels:
        docs.koreo.dev/from-function: label

  testCases:
  - label: Template One
    expectResource:
      apiVersion: koreo.dev/v1beta1
      kind: TestDummy
      metadata:
        name: test-demo-template-docs
        namespace: tests
        labels:
          docs.koreo.dev/example: template-label
          docs.koreo.dev/from-function: label
      spec:
        value: 42
        addedProperty: 714
        nested:
        - 1
        - 2

  - label: Template Two
    inputOverrides:
      template: two
    expectResource:
      apiVersion: koreo.dev/v1beta1
      kind: TestDummy
      metadata:
        name: test-demo-template-docs
        namespace: tests
        labels:
          docs.koreo.dev/example: template-label
          docs.koreo.dev/from-function: label
        annotations:
          docs.koreo.dev/example: template-two
      spec:
        value: 42
        addedProperty: 714
        structure:
        - name: doc
        - name: examples

Specification

v1beta1

Name	Type	Description	Required
apiVersion	string	koreo.dev/v1beta1	true
kind	string	ResourceTemplate	true
metadata	object	Refer to the Kubernetes API documentation for the fields of the metadata field.	true
spec	object		false
status	object		false

spec

Name	Type	Description	Required
template	RawExtension		true
context	object		false