Choosing the Right Scaffold for MySQL Operator: Kubebuilder vs Operator SDK

This is the second part of the MySQL Operator design series; the first introduced the overall architecture and design ideas. This part focuses on selecting an operator scaffolding tool and creating the project.

Operator Scaffolding Selection

Just as a construction site needs a scaffold for safe and fast building, an Operator project needs a scaffold to accelerate development and iteration. The Kubernetes community offers several mature scaffolding tools.

Operator Framework SDK : https://operatorframework.io/

Kubebuilder : https://book.kubebuilder.io/

KUDO (Kubernetes Universal Declarative Operator) : https://kudo.dev/

Charmed Operator Framework : https://juju.is/

The most active and widely used tools are Operator SDK and Kubebuilder . Both rely on the official controller‑tools and controller‑runtime, share a similar project layout, and differ in features.

Kubebuilder

Includes the envtest package for isolated etcd and apiserver testing.

Automatically generates a Makefile to build, test, run, and generate code.

Uses kustomize to build deployment manifests.

Improved support for admission and CRD conversion WebHooks.

Operator SDK

Better support for higher‑level operators such as Ansible and Helm.

Integrates with Operator Lifecycle Manager (OLM) for upgrades and management.

Provides a scorecard sub‑command to verify best‑practice compliance.

Includes an e2e testing framework for real‑cluster tests.

Because the two ecosystems are converging and Operator SDK is moving toward Kubebuilder, we chose the more native Kubebuilder (currently at version 3.0) as the scaffolding for this project.

Creating the Project

Initialize Operator and Controller API

Kubebuilder offers quick tutorials and scaffolding for generating code related to CRDs and controller APIs. The architecture is illustrated below:

Creation Steps

Follow these two steps to create the project:

Initialize the Operator project Run the following command (domain set to radondb.com ) to generate the Makefile, image build script, configuration files, and main.go : kubebuilder init --domain=radondb.com Create the Controller Specify the API group, version, and kind as mysql , v1alpha1 , and MysqlCluster respectively, and enable both the resource and controller scaffolding:

kubebuilder create api --group mysql --version v1alpha1 --kind MysqlCluster --resource=true --controller=true

After executing the second command, the project gains api, crd, and controllers directories.

Design Goals

The following shows the current directory structure and function overview of the radondb-mysql-kubernetes project.

Summary

The Operator builds on Kubernetes resources and controller concepts while embedding application‑specific domain knowledge. Designing a robust Operator hinges on well‑crafted Custom Resource Definitions (CRDs). The next article will analyze the CRD design of the radondb‑mysql‑kubernetes project.