kubebuilder VS kubegres

By default, operators built using Kubebuilder and controller-runtime process a single reconcile request at a time. This is a sensible setting, since it's easier for operator developers to reason about and debug the logic in their applications. It also constrains throughput from the controller to core Kubernetes resources like ectd and the API server.

client-go is the official Golang client for Kubernetes, responsible for interacting with the Kubernetes API server using REST API. In fact, client-go can do almost anything, not just for writing operators. Even the internal implementation of kubectl is based on client-go. As for more specialized frameworks used to write operators, including controller-runtime, kubebuilder, and operator-sdk, they will be introduced later in this series.

And it is only because of the focus on extensibility and interoperability that today, we can run WebAssembly workloads in Kubernetes so seamlessly. SpinKube is an open source stack of projects for running WebAssembly applications. A core piece of the stack is a containerd shim. I remember when containerd was donated to the CNCF in 2017. That took work and collaboration from several companies, most notably Docker, to make happen. SpinKube also depends on CRDs and operators. I recall seeing one the early demos of scaffolding an operator and a CRD in a SIG meeting from Phillip Wittrock, who went on to work on Kubebuilder in a Kubernetes SIG. Kubebuilder is a key piece of SpinKube’s Spin operator development. As I reflect on the last decade, I appreciate every contribution even more deeply.

Kubebuilder, a framework by Kubernetes SIGs, simplifies creating Kubernetes APIs using Custom Resource Definitions.

The Spin operator uses the Kubebuilder framework and contains a Spin App Custom Resource Definition (CRD) and controller. It watches Spin App Custom Resources and realizes the desired state in the K8s cluster. Aside from the immediate benefits gained by running Wasm workloads in k8s, additional optimizations such as Horizontal Pod Scaling (HPA) and k8s Event-driven Autoscaling (KEDA) can be achieved in a pinch.

kubebuilder: brew install kubebuilder

The operator that I've been working on is designed to manage the full lifecycle of a QuestDB database instance, including version and hardware upgrades, config changes, backups, and (eventually) recovery from node failure. I used the Operator SDK and kubebuilder frameworks to provide scaffolding and API support.

Recently, I've been spending a lot of time writing a Kubernetes operator using the go operator-sdk, which is built on top of the Kubebuilder framework. This is a list of a few tips and tricks that I've compiled over the past few months working with these frameworks.

Since we built our operator using the Kubebuilder framework, most standard monitoring tasks were handled for us out-of-the-box. Our operator automatically exposes a rich set of Prometheus metrics that measure reconciliation performance, the number of k8s API calls, workqueue statistics, and memory-related metrics. We we were able to ingest these metrics into pre-built dashboards by leveraging the grafana/v1-alpha plugin, which scaffolds two Grafana dashboards to monitor Operator resource usage and performance. All we had to do was add these to our existing Grafana manifests and we were good to go!

A good comparison with other operators here [2022]: https://blog.palark.com/cloudnativepg-and-other-kubernetes-o...

Personally I've only used Kubegres (https://www.kubegres.io/), which didn't even make the above list. It's ok for a personal project.

All k8s solutions for postgres take subtly different approaches. It seems that they've all converged on the Operator pattern. The basics are easy: run a database process which persists data to a cloud disk of your choice. The hard parts are how to update, migrate, backup, restore, monitor, failover, replicate, etc. These kubernetes "operators" promise to fulfill the role of a DBA but, just like hiring a DBA, it requires buy-in to their approach.

Reactive-Tech / Kubegres (opérateur)

I like https://www.kubegres.io, it takes a little getting used to how it works. I probably wouldn't use it for a huge database, but for things under a few TB it works great.

I don't know if you're using Kubernetes, but Kubegres is great for self hosting postgres on a cluster.

Any experience with https://www.kubegres.io/ ?

How does this compare with something like kubegres?

https://www.kubegres.io/

https://www.kubegres.io/ has worked well for me. You can use custom images, provided they follow the conventions of the official postgres image. I haven't tried a major-version upgrade yet - my impression is that it will probably be a bit painful and involve some downtime and manual ops.

Some of the more advanced operators might better handle the upgrade problem? But in general, I've been happy with Kubegres for a ~10GB database with low traffic.

There are some great operators out there that make deployment and management easy. I use kubegres managed with pgadmin and it has been working well for me.

reactive-tech/kubegres (operator)