Quick Start

This Quick Start guide will cover:

Prerequisites

  • go version v1.24.5+
  • docker version 17.03+.
  • kubectl version v1.11.3+.
  • Access to a Kubernetes v1.11.3+ cluster.

Installation

Install kubebuilder:

# download kubebuilder and install locally.
curl -L -o kubebuilder "https://go.kubebuilder.io/dl/latest/$(go env GOOS)/$(go env GOARCH)"
chmod +x kubebuilder && sudo mv kubebuilder /usr/local/bin/

Create a Project

Create a directory, and then run the init command inside of it to initialize a new project. Follows an example.

mkdir -p ~/projects/guestbook
cd ~/projects/guestbook
kubebuilder init --domain my.domain --repo my.domain/guestbook

Create an API

Run the following command to create a new API (group/version) as webapp/v1 and the new Kind(CRD) Guestbook on it:

kubebuilder create api --group webapp --version v1 --kind Guestbook

OPTIONAL: Edit the API definition and the reconciliation business logic. For more info see Designing an API and What’s in a Controller.

If you are editing the API definitions, generate the manifests such as Custom Resources (CRs) or Custom Resource Definitions (CRDs) using

make manifests
Click here to see an example. (api/v1/guestbook_types.go) 

// GuestbookSpec defines the desired state of Guestbook
type GuestbookSpec struct {
	// INSERT ADDITIONAL SPEC FIELDS - desired state of cluster
	// Important: Run "make" to regenerate code after modifying this file

	// Quantity of instances
	// +kubebuilder:validation:Minimum=1
	// +kubebuilder:validation:Maximum=10
	Size int32 `json:"size"`

	// Name of the ConfigMap for GuestbookSpec's configuration
	// +kubebuilder:validation:MaxLength=15
	// +kubebuilder:validation:MinLength=1
	ConfigMapName string `json:"configMapName"`

	// +kubebuilder:validation:Enum=Phone;Address;Name
	Type string `json:"type,omitempty"`
}

// GuestbookStatus defines the observed state of Guestbook
type GuestbookStatus struct {
	// INSERT ADDITIONAL STATUS FIELD - define observed state of cluster
	// Important: Run "make" to regenerate code after modifying this file

	// PodName of the active Guestbook node.
	Active string `json:"active"`

	// PodNames of the standby Guestbook nodes.
	Standby []string `json:"standby"`
}

// +kubebuilder:object:root=true
// +kubebuilder:subresource:status
// +kubebuilder:resource:scope=Cluster

// Guestbook is the Schema for the guestbooks API
type Guestbook struct {
	metav1.TypeMeta   `json:",inline"`
	metav1.ObjectMeta `json:"metadata,omitempty"`

	Spec   GuestbookSpec   `json:"spec,omitempty"`
	Status GuestbookStatus `json:"status,omitempty"`
}

Test It Out

You’ll need a Kubernetes cluster to run against. You can use KinD to get a local cluster for testing, or run against a remote cluster.

Install the CRDs into the cluster:

make install

For quick feedback and code-level debugging, run your controller (this will run in the foreground, so switch to a new terminal if you want to leave it running):

make run

Install Instances of Custom Resources

If you pressed y for Create Resource [y/n] then you created a CR for your CRD in your samples (make sure to edit them first if you’ve changed the API definition):

kubectl apply -k config/samples/

Run It On the Cluster

When your controller is ready to be packaged and tested in other clusters.

Build and push your image to the location specified by IMG:

make docker-build docker-push IMG=<some-registry>/<project-name>:tag

Deploy the controller to the cluster with image specified by IMG:

make deploy IMG=<some-registry>/<project-name>:tag

Uninstall CRDs

To delete your CRDs from the cluster:

make uninstall

Undeploy controller

Undeploy the controller to the cluster:

make undeploy

Using Plugins

Kubebuilder design is based on Plugins and you can use available plugins to add optional features to your project.

Creating an API and Controller with code to manage an image

For example, you can scaffold an API and controller that manages container images by using the deploy-image plugin:

kubebuilder create api --group webapp --version v1alpha1 --kind Busybox --image=busybox:1.36.1 --plugins="deploy-image/v1-alpha"

This command generates:

  • The API definition in api/v1alpha1/busybox_types.go.
  • The controller logic in internal/controllers/busybox_controller.go.
  • A test scaffold in internal/controllers/busybox_controller_test.go, which uses EnvTest for integration-style testing.

Keeping your project up to date with ecosystem changes

Kubebuilder provides the AutoUpdate Plugin to help keep your project aligned with the latest ecosystem changes. When a new release is available, the plugin opens an Issue with a Pull Request compare link. You can then review the updates and, if helpful, use GitHub AI models to understand what changes are needed to keep your project current.

kubebuilder edit --plugins="autoupdate/v1-alpha"

This command scaffolds a GitHub workflow file at .github/workflows/autoupdate.yml.

Next Step