Quick Start

This Quick Start guide will cover:

• Creating a project
• Creating an API
• Running locally
• Running in-cluster

Prerequisites

• go version v1.19.0+
• 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 && 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 Defintions (CRDs) using

make manifests

// 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:"alias,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

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 -f config/samples/

Run It On the Cluster

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

Next Step

Now, see the architecture concept diagram for a better overview and follow up the CronJob tutorial to better understand how it works by developing a demo example project.