Demo Scaffold The Same Operator With Operator SDK

You previously built a web app operator using Kubebuilder. In this lesson you’ll scaffold the same Go operator with the Operator SDK and compare the resulting project layout. The objective is to observe the initial scaffold and reconcile model—this is not a walkthrough to re-implement the web app logic. This guide covers:

Prerequisites
Installing the operator-sdk CLI (Linux / macOS)
Initializing a new Go operator project
Creating the WebApp API and controller
Inspecting generated code and manifests
Comparing the generated PROJECT layout and plugins

Prerequisites

Go toolchain installed and configured (Go 1.19+ recommended)
Git and curl available
Optional: a disposable workspace (example: an ephemeral container or temporary directory)

Install operator-sdk

Linux installation (recommended steps)

Download the release binary for your architecture, verify the signed checksums, and place the binary on your PATH as operator-sdk.

export OPERATOR_SDK_VERSION=v1.42.2
export OPERATOR_SDK_DL_URL="https://github.com/operator-framework/operator-sdk/releases/download/${OPERATOR_SDK_VERSION}"
curl -LO "${OPERATOR_SDK_DL_URL}/operator-sdk_linux_amd64"
curl -LO "${OPERATOR_SDK_DL_URL}/checksums.txt"
curl -LO "${OPERATOR_SDK_DL_URL}/checksums.txt.asc"

Import and verify the release signing key, then verify the checksums:

gpg --keyserver keyserver.ubuntu.com --recv-keys 052996E2A20B5C7E
gpg --verify checksums.txt.asc checksums.txt
sha256sum --check --ignore-missing checksums.txt
# expected output:
# operator-sdk_linux_amd64: OK

Make the binary executable and move it into a location on your PATH:

chmod +x operator-sdk_linux_amd64
sudo mv operator-sdk_linux_amd64 /usr/local/bin/operator-sdk

macOS (Homebrew)

You can also install via Homebrew on macOS:

brew install operator-sdk

Verify the CLI is available and inspect the binary metadata:

operator-sdk version
# sample output:
# operator-sdk version: "v1.42.2", commit: "6001c29067051e1a04e829ea033988b904d1845e", kubernetes version: "1.33.1", go version: "go1.25.7", GOOS: "linux", GOARCH: "amd64"

Note: the reported “kubernetes version” refers to the Kubernetes client libraries bundled with the SDK binary, not your cluster version.

If you are already familiar with the Kubebuilder scaffold, the operator-sdk Go scaffold will feel familiar: you still write API types and a reconciler, and you still run a controller manager. operator-sdk layers additional tooling and plugins (manifests, scorecard, OLM) around that shared foundation.

Initialize a clean Go operator-sdk project

Start from an empty directory (for disposable workspaces you may run rm -rf *).

rm -rf *
operator-sdk init --domain=kodekloud.com --repo=github.com/kodekloud/webapp-sdk --plugins=go/v4

What to watch for as the project initializes:

controller-runtime and Go module setup (the same controller-runtime library Kubebuilder uses).
Code generation steps (e.g., make generate, go generate) and go mod tidy.

This confirms the operator runtime foundation (manager, client, event watching, reconcile loop) is shared between Kubebuilder and operator-sdk.

Create the WebApp API and controller

Scaffold the API group webapp, version v1, and kind WebApp. Use --resource to scaffold the CRD types and --controller to add a reconciler skeleton.

operator-sdk create api --group webapp --version v1 --kind WebApp --resource --controller

Typical generated artifacts:

api/v1/webapp_types.go
internal/controller/webapp_controller.go
internal/controller/webapp_controller_test.go

The SDK also runs go mod tidy and the codegen tasks to produce boilerplate.

Inspect the generated code

API types are located under api/v1. The reconciler skeleton is under internal/controller (in some layouts it may appear under controllers). This separation mirrors the conceptual boundaries used by Kubebuilder. A corrected sample of the generated list type (ensure your generated WebAppList resembles this):

package v1

import (
    metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
)

// WebAppList contains a list of WebApp
type WebAppList struct {
    metav1.TypeMeta `json:",inline"`
    metav1.ListMeta `json:"metadata,omitempty"`
    Items           []WebApp `json:"items"`
}

func init() {
    SchemeBuilder.Register(&WebApp{}, &WebAppList{})
}

Generate manifests

After you implement API fields and reconciliation logic, generate the manifests (CRDs, RBAC, webhook manifests if applicable):

make manifests

This produces the CRD YAML, RBAC roles, and other required manifests for deploying your operator.

Comparing the PROJECT layout

The PROJECT file is the most useful artifact when comparing scaffolds. It records the project layout and plugins the scaffold used. operator-sdk, when configured with the Kubebuilder Go layout, will include entries reflecting the Go layout plus operator-sdk plugins (manifests, scorecard, OLM). Representative PROJECT fragment:

domain: kodekloud.com
layout:
  - go.kubebuilder.io/v4
plugins:
  manifests.sdk.operatorframework.io/v2: {}
  scorecard.sdk.operatorframework.io/v2: {}
projectName: webapp-sdk
repo: github.com/kodekloud/webapp-sdk
resources:
  - api:
      crdVersion: v1
      namespaced: true
      controller: true
      domain: kodekloud.com
      group: webapp
      kind: WebApp
      path: github.com/kodekloud/webapp-sdk/api/v1
      version: v1
version: "3"

Quick comparison table: Kubebuilder vs operator-sdk scaffolds

Area	Kubebuilder	Operator SDK (Go plugin)
Controller runtime	controller-runtime (same)	controller-runtime (same)
Project layout	Kubebuilder Go layout	Kubebuilder Go layout (via plugin)
Extra tooling	Minimal by default	Plugins for manifests, scorecard, OLM, packaging
Common files	`api/`, `controllers/`	`api/`, `internal/controller/` (layout may vary)
Packaging & validation	Manual or external	Built-in plugin support for OLM, scorecard, manifests

Files you typically see after scaffold:

Path	Purpose
`api/v1/webapp_types.go`	API type definitions and CRD annotations
`api/v1/webapp_webhook.go`	(Optional) Webhook scaffolding
`internal/controller/webapp_controller.go`	Reconciler skeleton and business logic entrypoint
`PROJECT`	Records layout, plugins, and resources
`config/` or `make` targets	Generated manifests and deployment resources

Key takeaway

The operator-sdk Go plugin uses the same controller-runtime and Kubebuilder-style project layout. The primary differences are the tooling additions and plugins operator-sdk provides for packaging, validation, and distribution (OLM/scorecard). If you understand the Kubebuilder workflow, the operator-sdk Go scaffold will be immediately recognizable and comfortable to work with.

Links and references

Watch Video

Operator SDK Its Relationship To Kubebuilder

Helm Based Operators Wrap A Chart As An Operator

Introduction to Operator Fundamentals

Custom Resource Definitions Deep Dive

Kubebuilder Scaffolding

Building The WebApp Operator Core Reconcile

Running Testing Debugging Locally

Status Conditions Events

Finalizers And Cleanup

Validation Webhooks And CEL Policies

Packaging And Distribution

Alternative Approaches Operator SDK Helm Operator

Consuming Popular Operators

Production Readiness Testing Wrap Up

Demo Scaffold The Same Operator With Operator SDK

Prerequisites

Install operator-sdk

Linux installation (recommended steps)

macOS (Homebrew)

Initialize a clean Go operator-sdk project

Create the WebApp API and controller

Inspect the generated code

Generate manifests

Comparing the PROJECT layout

Key takeaway

Links and references

Watch Video

​Prerequisites

​Install operator-sdk

​Linux installation (recommended steps)

​macOS (Homebrew)

​Initialize a clean Go operator-sdk project

​Create the WebApp API and controller

​Inspect the generated code

​Generate manifests

​Comparing the PROJECT layout

​Key takeaway

​Links and references

Watch Video

Prerequisites

Install operator-sdk

Linux installation (recommended steps)

macOS (Homebrew)

Initialize a clean Go operator-sdk project

Create the WebApp API and controller

Inspect the generated code

Generate manifests

Comparing the PROJECT layout

Key takeaway

Links and references