kubebuilder VS crossplane

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!

The most obvious alternative to Pulumi is Terraform. But hey, keep an eye out for OpenTofu, an upcoming open-source alternative following a BSL license change. Crossplane is another alternative for those who enjoy building infrastructure using Kubernetes CRDs. Check out more details below.

did anyone adopt in production https://crossplane.io ?

- https://github.com/crossplane/crossplane/blob/master/design/one-pager-composition-environment.md

In the overall scheme of things , look at services like backstage.io , crossplane.io and opslevel.com to get ideas. This is not necessarily an endorsement of the services. If all you want is to handle cloud resources and that's it, Terraform can be enough with what ever flavor of web technologies you and your team are comfortable with and can support it along the way. Doesn't take much to create a js based website to collect data from a form, or use other means to collecting data as long as its recorded and transparent for accountability.

XRs are written in a fully declarative manner. And when I am building my XR from underlying managed resources provided by some crossplane provider I need to parametrize resources, use conditionals and create arrays of resuorces The issues of declarativeness in the world of automation are well known- we typically resort to some form of templating and we invent some imperative expressions into that templating language/format. This is currently not very well supported with Crossplane however Crossplane team realizes this issue and they are conteptualizing solution here

I have an idea for a project that would interface with Crossplane. The project has some code that would save tons of time if I could use it directly in my project, but it is located in the internal directory. I can't import the modules directly, but the project is open sourced under an Apache 2.0 license, so the code itself is available for use under that license.

There are always new projects like crossplane that sit on top on architecture systems like terraform, vagrant. The pressure to abstract away any sort of resources is mounting, companies can save a lot by for example by alt hosting S3 endpoints. The train is going the direction not to tie anything to a specific platform implementation if its not a must. Most of the companies I work with use AWS as a hosting provider, but Microsoft for github and related CI matters. As I learned, AWS quality is very dependent on location, eu-central-1 is dead stable for our use cases serving about millions requests a day.