templating-controller

Generic Templating Controller

This controller fetches the given StackDefinition custom resource as configuration and reconciles the given CustomResourceDefinition with specified behavior.

The controller will construct a reconciler in the initialization phase and register it to the api-server to receive events for the CRD given in spec.behavior.crd. The reconciler is constructed with the configuration under spec.behavior.engine.

Here is an example StackDefinition object that uses kustomize engine:

---
apiVersion: stacks.crossplane.io/v1alpha1
kind: StackDefinition
metadata:
  name: template-stack-test
spec:
  behavior:
    source:
      image: crossplane/stack-minimal-gcp:0.1.0
      path: "kustomize"
    crd:
      kind: MinimalGCP
      apiVersion: gcp.resourcepacks.crossplane.io/v1alpha1
    engine:
      type: kustomize
      kustomize:
        overlays:
          - apiVersion: gcp.crossplane.io/v1alpha3
            kind: Provider
            name: gcp-provider
            bindings:
              - from: "spec.credentialsSecretRef"
                to: "spec.credentialsSecretRef"
              - from: "spec.projectID"
                to: "spec.projectID"
          - apiVersion: cache.gcp.crossplane.io/v1beta1
            kind: CloudMemorystoreInstanceClass
            name: cloudmemorystore
            bindings:
              - from: "spec.region"
                to: "specTemplate.forProvider.region"

The reconciler will use kustomize as engine and it will produce an overlay with the given objects above. What's happening there is that a Provider object will be created as strategic patch overlay with two bindinds; from is the field path for the actual CR instance and to is the field path of the field on the Provider object.

The following is an example that uses Helm 3 engine:

---
apiVersion: stacks.crossplane.io/v1alpha1
kind: StackDefinition
metadata:
  name: template-stack-test
spec:
  behavior:
    source:
      image: crossplane/sample-stack-wordpress:0.1.0
      path: "helm-chart"
    crd:
      kind: WordpressInstance
      apiVersion: wordpress.samples.stacks.crossplane.io/v1alpha1
    engine:
      type: helm3

A big difference here is that there is no overlay. The spec of an instance of the Custom Resource is directly translated to be used as values.yaml in the helm chart.

See test folder to give it a spin.

Build

Run make to build the latest version.