Define the CartsStack RGD

A ResourceGraphDefinition is the heart of kro: it declares a new Kubernetes API kind and the graph of resources that get created whenever someone applies an instance of that kind.

The CartsStack RGD we'll define in this lab takes a couple of simple inputs (tableName, namespace, plus optional image and replicas) and expands into the full carts stack — a Namespace, an ACK Table, a ConfigMap, a ServiceAccount, a Deployment running the carts container, and a Service so other components can reach it. Here's an excerpt of the manifest we'll apply:

apiVersion: kro.run/v1alpha1
kind: ResourceGraphDefinition
metadata:
  name: cartsstack
spec:
  schema:
    apiVersion: v1alpha1
    kind: CartsStack
    group: kro.run
    spec:
      tableName: string | required=true
      namespace: string | required=true
      image: string | default="public.ecr.aws/aws-containers/retail-store-sample-cart:1.2.1"
      replicas: integer | default=1
    status:
      tableArn: ${table.status.ackResourceMetadata.arn}
  resources:
    - id: ns
      template:
        apiVersion: v1
        kind: Namespace
        metadata: { name: ${schema.spec.namespace} }
    - id: table
      template:
        apiVersion: dynamodb.services.k8s.aws/v1alpha1
        kind: Table
        metadata: { name: items, namespace: ${schema.spec.namespace} }
        spec:
          tableName: ${schema.spec.tableName}
          billingMode: PAY_PER_REQUEST
          # ...key schema + GSI omitted for brevity
    - id: sa
      template:
        apiVersion: v1
        kind: ServiceAccount
        metadata: { name: carts, namespace: ${schema.spec.namespace} }
    - id: config
      template:
        apiVersion: v1
        kind: ConfigMap
        metadata: { name: carts, namespace: ${schema.spec.namespace} }
        data:
          RETAIL_CART_PERSISTENCE_PROVIDER: dynamodb
          RETAIL_CART_PERSISTENCE_DYNAMODB_TABLE_NAME: ${schema.spec.tableName}
    - id: deployment
      template:
        apiVersion: apps/v1
        kind: Deployment
        metadata: { name: carts, namespace: ${schema.spec.namespace} }
        spec:
          replicas: ${schema.spec.replicas}
          # ...selector, podSpec wired to the SA + ConfigMap above
    - id: service
      template:
        apiVersion: v1
        kind: Service
        metadata: { name: carts, namespace: ${schema.spec.namespace} }
        spec:
          type: ClusterIP
          ports: [{ port: 80, targetPort: http, name: http }]

A few things to notice:

• spec.schema declares the shape of the user-facing CR. kro uses a SimpleSchema syntax (the string | required=true form), not raw OpenAPI. Optional fields like image and replicas get sensible defaults so a minimal instance only has to set tableName and namespace.
• spec.resources is the graph kro will create. Each entry has an id (used to reference its outputs from other resources) and a template (the actual manifest).
• ${schema.spec.X} references fields from the user's instance. ${table.status.ackResourceMetadata.arn} references runtime status from another resource — kro orders the graph so table is created before anything that reads its status.
• ${sa.metadata.name} and ${config.metadata.name} in the Deployment template are how the Pod's serviceAccountName and envFrom.configMapRef.name get wired up — kro infers the dependency from these references, so the Deployment is created only after the SA and ConfigMap exist.

Apply the RGD:

~$kubectl apply -k ~/environment/eks-workshop/modules/fastpaths/eks-capabilities/kro/rgd

resourcegraphdefinition.kro.run/cartsstack created

kro validates the RGD synchronously: it type-checks every ${...} expression against the actual Kubernetes schemas of the resources you reference, and detects circular dependencies. If anything is wrong, the apply fails immediately with a descriptive error.

Wait for the RGD to reach Active — at this point kro has dynamically generated and registered the CartsStack CRD in the cluster:

~$kubectl wait rgd cartsstack --for=jsonpath='{.status.state}'=Active --timeout=60s

resourcegraphdefinition.kro.run/cartsstack condition met

Confirm the new CartsStack kind is now a first-class Kubernetes API:

~$kubectl api-resources --api-group=kro.run | grep -E 'NAME|cartsstacks'

NAME                       SHORTNAMES   APIVERSION         NAMESPACED   KIND

cartsstacks                             kro.run/v1alpha1   true         CartsStack

備考

cartsstacks is namespaced even though the RGD that defines it is cluster-scoped. RGDs live cluster-wide; instances always live in a specific namespace.

The schema exists. Next we'll apply an instance.