We're continuing to see increasing use of the Kubernetes Operator pattern for purposes other than managing applications deployed on the cluster. Using the Operator pattern for nonclustered resources takes advantage of custom resource definitions and the event-driven scheduling mechanism implemented in the Kubernetes control plane to manage activities that are related to yet outside of the cluster. This technique builds on the idea of Kube-managed cloud services and extends it to other activities, such as continuous deployment or reacting to changes in external repositories. One advantage of this technique over a purpose-built tool is that it opens up a wide range of tools that either come with Kubernetes or are part of the wider ecosystem. You can use commands such as diff, dry-run or apply to interact with the operator's custom resources. Kube's scheduling mechanism makes development easier by eliminating the need to orchestrate activities in the proper order. Open-source tools such as Crossplane, Flux and Argo CD take advantage of this technique, and we expect to see more of these emerge over time. Although these tools have their use cases, we're also starting to see the inevitable misuse and overuse of this technique and need to repeat some old advice: Just because you can do something with a tool doesn't mean you should. Be sure to rule out simpler, conventional approaches before creating a custom resource definition and taking on the complexity that comes with this approach.
We're seeing increasing use of the Kubernetes Operator pattern for purposes other than managing applications deployed on the cluster. Using the operator pattern for nonclustered resources takes advantage of custom resource definitions and the event-driven scheduling mechanism implemented in the Kubernetes control plane to manage activities that are related to yet outside of the cluster. This technique builds on the idea of Kube-managed cloud services and extends it to other activities, such as continuous deployment or reacting to changes in external repositories. One advantage of this technique over a purpose-built tool is that it opens up a wide range of tools that either come with Kubernetes or are part of the wider ecosystem. You can use commands such as diff, dry-run or apply to interact with the operator's custom resources. Kube's scheduling mechanism makes development easier by eliminating the need to orchestrate activities in the proper order. Open-source tools such as Crossplane, Flux and ArgoCD take advantage of this technique and we expect to see more of these emerge over time.
