Bits of .NET

🔌 Define Your Own Kubernetes Objects

Kubernetes has Pods, Services, Deployments. Custom Resource Definitions (CRD) create your own objects. Extend Kubernetes for your needs.

📝 Create a CRD

apiVersion: apiextensions.k8s.io/v1
kind: CustomResourceDefinition
metadata:
  name: databases.myapp.com
spec:
  group: myapp.com
  versions:
  - name: v1
    served: true
    storage: true
    schema:
      openAPIV3Schema:
        type: object
        properties:
          spec:
            type: object
            properties:
              engine:
                type: string
                enum: ["postgres", "mysql"]
              version:
                type: string
              replicas:
                type: integer
                minimum: 1
                maximum: 10
  scope: Namespaced
  names:
    plural: databases
    singular: database
    kind: Database
    shortNames:
    - db

🎯 Use Custom Resource

apiVersion: myapp.com/v1
kind: Database
metadata:
  name: my-postgres
spec:
  engine: postgres
  version: "15"
  replicas: 3

# Apply CRD
kubectl apply -f database-crd.yaml

# Create custom resource
kubectl apply -f my-postgres.yaml

# List custom resources
kubectl get databases
kubectl get db

# Describe
kubectl describe database my-postgres

💡 Use Cases

• Database CRD (PostgreSQL, MySQL)
• Application deployment CRD
• Resource quota CRD (custom limits)
• Config management CRD
• Operator pattern (controller manages CRD)