sample-controller VS percona-server-mongodb-operator

- Sample controller: https://github.com/kubernetes/sample-controller

The most low-level approach I have seen is using the client-go package. Both kubebuilder and controller-runtime are based on this package. You can see an official example here: https://github.com/kubernetes/sample-controller/blob/master/docs/controller-client-go.md But even that sample requires some code generation on top of it https://cloud.redhat.com/blog/kubernetes-deep-dive-code-generation-customresources

I would still recommend gitOps tools or if you want to create your own abstraction (CRD) that encapsulates whatever behaviour you want to watch/act upon, take a look into kubernetes sample controller (https://github.com/kubernetes/sample-controller) or the kubernetes operator pattern https://kubernetes.io/docs/concepts/extend-kubernetes/operator/

Either should be fine. In case though you want something more basic then consider sample-controller: https://github.com/kubernetes/sample-controller

As far as Operator development goes, if you are comfortable with golang then I would recommend checking out sample-controller https://github.com/kubernetes/sample-controller It does not abstract the underlying client-go machinery and so provides a good way to understand how various parts of an Operator come together. On the other hand, if you don't want to get exposed to that much details then either Operator SDK or Kubebuilder will be good options. In case you are not into golang then there are SDKs for other languages as well (Python, Java, etc.).

Cool! Given that you mention you are a beginner in K8s operator development, here is a plan that I would like to suggest. 1. Get basic understanding of Kubernetes custom controllers first. The sample controller repo is a good place to start. https://github.com/kubernetes/sample-controller

the sample controller using client-go to learn about informers: https://github.com/kubernetes/sample-controller

Deploying the Percona Operator for MongoDB using ArgoCD represents a significant step forward in managing complex database systems within Kubernetes. By integrating Helm charts with GitOps principles, organizations can achieve more consistent, scalable, and error-resistant deployments.

It's the turn of percona/percona-server-mongodb-operator; Denys Kondratenko is the maintainer of this project. It is an excellent opportunity to learn about Kubernetes and how to extend it and maintain stateful databases inside Kubernetes. Most of the things are tracked in GitHub and Jira.