Implementing Custom Resource Definitions With Kubernetes Operators

This Pulumi program demonstrates how to implement custom resource definitions (CRDs) with Kubernetes Operators. The program will define a CRD and then create a Kubernetes Operator to manage instances of this CRD.

Introduction

In this solution, we will use Pulumi to define a Kubernetes Custom Resource Definition (CRD) and implement a Kubernetes Operator to manage the lifecycle of custom resources. The key services involved are the Kubernetes API and Pulumi’s Kubernetes provider.

Step-by-Step Explanation

Step 1: Define the Custom Resource Definition (CRD)

First, we will define the CRD using Pulumi’s Kubernetes provider. The CRD will specify the schema for the custom resource.

Step 2: Create the Kubernetes Operator

Next, we will create a Kubernetes Operator that will manage instances of the custom resource defined by the CRD. The Operator will watch for changes to the custom resources and perform actions accordingly.

Step 3: Deploy the CRD and Operator

Finally, we will deploy the CRD and the Operator to the Kubernetes cluster using Pulumi.

Summary

In this solution, we defined a Kubernetes Custom Resource Definition (CRD) and implemented a Kubernetes Operator to manage the lifecycle of custom resources. This approach allows for the automation of complex application management tasks in Kubernetes.

Full Code Example

import * as pulumi from "@pulumi/pulumi";
import * as k8s from "@pulumi/kubernetes";

// Define the Custom Resource Definition (CRD)
const crd = new k8s.apiextensions.v1.CustomResourceDefinition("mycrd", {
    metadata: { name: "myresources.mydomain.com" },
    spec: {
        group: "mydomain.com",
        versions: [{
            name: "v1",
            served: true,
            storage: true,
            schema: {
                openAPIV3Schema: {
                    type: "object",
                    properties: {
                        spec: {
                            type: "object",
                            properties: {
                                foo: { type: "string" },
                                bar: { type: "integer" },
                            },
                        },
                    },
                },
            },
        }],
        scope: "Namespaced",
        names: {
            plural: "myresources",
            singular: "myresource",
            kind: "MyResource",
            shortNames: ["mr"],
        },
    },
});

// Define the Kubernetes Operator (Deployment)
const operator = new k8s.apps.v1.Deployment("my-operator", {
    metadata: { name: "my-operator" },
    spec: {
        selector: { matchLabels: { app: "my-operator" } },
        replicas: 1,
        template: {
            metadata: { labels: { app: "my-operator" } },
            spec: {
                containers: [{
                    name: "my-operator",
                    image: "my-operator-image:latest",
                    env: [{ name: "WATCH_NAMESPACE", valueFrom: { fieldRef: { fieldPath: "metadata.namespace" } } }],
                }],
            },
        },
    },
});

// Define a Service for the Operator
const operatorService = new k8s.core.v1.Service("my-operator-service", {
    metadata: { name: "my-operator-service" },
    spec: {
        selector: { app: "my-operator" },
        ports: [{ port: 80, targetPort: 8080 }],
    },
});

// Export the CRD name
export const crdName = crd.metadata.name;
export const operatorName = operator.metadata.name;
export const operatorServiceName = operatorService.metadata.name;