FAQ

1. What is kro?

   Kube Resource Orchestrator (kro) is a new operator for Kubernetes that simplifies the creation of complex Kubernetes resource configurations. kro lets you create and manage custom groups of Kubernetes resources by defining them as a ResourceGraphDefinition, the project's fundamental custom resource. ResourceGraphDefinition specifications define a set of resources and how they relate to each other functionally. Once defined, resource groups can be applied to a Kubernetes cluster where the kro controller is running. Once validated by kro, you can create instances of your resource group. kro translates your ResourceGraphDefinition instance and its parameters into specific Kubernetes resources and configurations which it then manages for you.

2. How does kro work?

   kro is designed to use core Kubernetes primitives to make resource grouping, customization, and dependency management simpler. When a ResourceGraphDefinition is applied to the cluster, the kro controller verifies its specification, then dynamically creates a new CRD and registers it with the API server. kro then deploys a dedicated controller to respond to instance events on the CRD. This microcontroller is responsible for managing the lifecycle of resources defined in the ResourceGraphDefinition for each instance that is created.

3. How do I use kro?

   First, you define your custom resource groups by creating ResourceGraphDefinition specifications. These specify one or more Kubernetes resources, and can include specific configuration for each resource.

   For example, you can define a WebApp resource group that is composed of a Deployment, pre-configured to deploy your web server backend, and a Service configured to run on a specific port. You can just as easily create a more complex WebAppWithDB resource group by combining the existing WebApp resource group with a Table custom resource to provision a cloud managed database instance for your web app to use.

   Once you have defined a ResourceGraphDefinition, you can apply it to a Kubernetes cluster where the kro controller is running. kro will take care of the heavy lifting of creating CRDs and deploying dedicated controllers in order to manage instances of your new custom resource group.

   You are now ready to create instances of your new custom resource group, and kro will respond by dynamically creating, configuring, and managing the underlying Kubernetes resources for you.

4. Why did you build this project?

   We want to help streamline and simplify building with Kubernetes. Building with Kubernetes means dealing with resources that need to operate and work together, and orchestrating this can get complex and difficult at scale. With this project, we're taking a first step in reducing the complexity of resource dependency management and customization, paving the way for a simple and scalable way to create complex custom resources for Kubernetes.

5. How do I use KRO resources with ArgoCD?

   To use KRO resources with ArgoCD, you need to add a specific tracking annotation to all templated resources in your ResourceGraphDefinition.

   The following code needs to be added to each templated resource:

   metadata:
      ownerReferences:
         - apiVersion: kro.run/v1alpha1
           kind: ${schema.kind}
           name: ${schema.metadata.name}
           uid: ${schema.metadata.uid}
           blockOwnerDeletion: true
           controller: false
      annotations:
        argocd.argoproj.io/tracking-id: ${schema.metadata.?annotations["argocd.argoproj.io/tracking-id"]}

   This annotation allows ArgoCD to properly track and manage the resources created by KRO instances.

   

   Note that the example shown above depicts ArgoCD's default resource tracking via annotations. You may choose to use annotation+label or just label and if so the example has to be modified to support your configuration. For more detailed information about ArgoCD resource tracking, please see the ArgoCD documentation.

6. Can I use this in production?

   This project is in active development and not yet intended for production use. The ResourceGraphDefinition CRD and other APIs used in this project are not solidified and highly subject to change.