ExampleCorp Order System: ACK + KRO Integrated Deployment

Last Updated: February 21, 2026

Scenario Overview

An end-to-end example of deploying ExampleCorp's Order API to Kubernetes. ACK provisions AWS infrastructure (NLB, Aurora PostgreSQL, Route 53), while KRO manages application resources (Deployment, Service, TargetGroupBinding, ConfigMap) as a single Custom Resource.

ACK (AWS Infrastructure)    KRO (App Deployment)
─────────────────────     ─────────────────────
NLB + TargetGroup    ←──  TargetGroupBinding
Aurora PostgreSQL    ←──  ConfigMap (endpoints)
Route 53 Record           Deployment + Service

ACK uses the ELBv2, Route 53, and RDS controllers described in the ACK document to create infrastructure, and KRO manages the application resources referencing this infrastructure as a single CR.

Architecture Diagram

Step 1: Infrastructure Provisioning with ACK

Use ACK controllers (elbv2, route53, rds) to provision the following infrastructure. For detailed YAML for each resource, see ACK Resource Examples.

• NLB + TargetGroup + Listener: Application traffic ingress
• Route 53 DNS Record: app.example.com → NLB mapping
• Aurora PostgreSQL: DBSubnetGroup + DBCluster + Writer + 2 Readers + Custom Endpoint

Step 2: KRO ResourceGraphDefinition

apiVersion: kro.run/v1alpha1
kind: ResourceGraphDefinition
metadata:
  name: webapp-graph
spec:
  resourceKind:
    group: kro.example.com
    kind: WebApp
    version: v1
  childResources:
    # 1. ConfigMap — Aurora connection info
    - apiVersion: v1
      kind: ConfigMap
      nameTemplate: "{{.parent.metadata.name}}-db-config"
      template: |
        data:
          DB_WRITER_HOST: "{{.parent.spec.aurora.writerEndpoint}}"
          DB_READER_HOST: "{{.parent.spec.aurora.readerEndpoint}}"
          DB_PORT: "{{.parent.spec.aurora.port}}"
          DB_NAME: "{{.parent.spec.aurora.dbName}}"

    # 2. Deployment — App container
    - apiVersion: apps/v1
      kind: Deployment
      nameTemplate: "{{.parent.metadata.name}}"
      template: |
        spec:
          replicas: {{.parent.spec.replicas}}
          selector:
            matchLabels:
              app: {{.parent.spec.appName}}
          template:
            metadata:
              labels:
                app: {{.parent.spec.appName}}
            spec:
              containers:
              - name: {{.parent.spec.appName}}
                image: {{.parent.spec.image}}
                ports:
                - containerPort: {{.parent.spec.port}}
                envFrom:
                - configMapRef:
                    name: {{.children.configmap.metadata.name}}

    # 3. Service — ClusterIP
    - apiVersion: v1
      kind: Service
      nameTemplate: "{{.parent.metadata.name}}"
      template: |
        spec:
          selector:
            app: {{.parent.spec.appName}}
          ports:
          - port: {{.parent.spec.port}}
            targetPort: {{.parent.spec.port}}
          type: ClusterIP

    # 4. TargetGroupBinding — ACK Target Group connection
    - apiVersion: elbv2.k8s.aws/v1beta1
      kind: TargetGroupBinding
      nameTemplate: "{{.parent.metadata.name}}-tgb"
      template: |
        spec:
          targetGroupARN: {{.parent.spec.targetGroupARN}}
          serviceRef:
            name: {{.children.service.metadata.name}}
            port: {{.parent.spec.port}}
          targetType: ip

  statusMappings:
    - childResource:
        kind: Deployment
        name: "{{.parent.metadata.name}}"
      conditions:
        - type: Available
          mapping:
            type: Ready
    - childResource:
        kind: Service
        name: "{{.parent.metadata.name}}"
      fieldMappings:
        - child: "spec.clusterIP"
          parent: "status.serviceIP"

Input Field Description

Field	Description
appName	Application name (used in labels, selectors)
image	Container image URI
replicas	Deployment replica count
port	Container and service port
targetGroupARN	Target Group ARN created by ACK
aurora.writerEndpoint	ACK DBCluster Writer endpoint
aurora.readerEndpoint	ACK DBCluster Reader endpoint
aurora.port	Aurora port (default 5432)
aurora.dbName	Database name

Step 3: Application Deployment

apiVersion: kro.example.com/v1
kind: WebApp
metadata:
  name: order-api
  namespace: production
spec:
  appName: order-api
  image: 123456789012.dkr.ecr.ap-northeast-2.amazonaws.com/order-api:v1.2.0
  replicas: 3
  port: 8080
  targetGroupARN: <ACK TargetGroup's .status.targetGroupARN>
  aurora:
    writerEndpoint: <ACK DBCluster's .status.endpoint>
    readerEndpoint: <ACK DBCluster's .status.readerEndpoint>
    port: "5432"
    dbName: orders

Inject the output values from ACK-created infrastructure (Target Group ARN, Aurora endpoints) into the KRO CR spec.

Step 4: Verification

# Check WebApp CR status
kubectl get webapp order-api -n production -o yaml

# Check created resources
kubectl get deploy,svc,targetgroupbinding,configmap -n production -l app=order-api

Operational Patterns

Adding New Services

Reuse existing infrastructure by simply adding a new WebApp CR:

apiVersion: kro.example.com/v1
kind: WebApp
metadata:
  name: payment-api
  namespace: production
spec:
  appName: payment-api
  image: 123456789012.dkr.ecr.ap-northeast-2.amazonaws.com/payment-api:v1.0.0
  replicas: 2
  port: 8080
  targetGroupARN: <new Target Group ARN>
  aurora:
    writerEndpoint: <existing Aurora Writer Endpoint>
    readerEndpoint: <existing Aurora Reader Endpoint>
    port: "5432"
    dbName: payments

Aurora Scaling

Add ACK DBInstances to horizontally scale Read Replicas:

apiVersion: rds.services.k8s.aws/v1alpha1
kind: DBInstance
metadata:
  name: my-aurora-reader-3
  namespace: infra
spec:
  dbInstanceIdentifier: my-aurora-reader-3
  dbClusterIdentifier: my-aurora-cluster
  dbInstanceClass: db.r6g.xlarge
  engine: aurora-postgresql

Blue/Green Deployment

Perform zero-downtime deployment by replacing the KRO CR. Applying a new version of the CR causes KRO to automatically update the Deployment.

Reference Documents

• ACK Concepts and Installation
• ACK Resource Examples: ELBv2, Route 53, RDS
• KRO Concepts and RGD