Quick Start

This Quick Start guide will cover:

Prerequisites

  • go version v1.12+.
  • docker version 17.03+.
  • kubectl version v1.11.3+.
  • kustomize v3.1.0+
  • Access to a Kubernetes v1.11.3+ cluster.

Installation

Install kubebuilder:

os=$(go env GOOS)
arch=$(go env GOARCH)

# download kubebuilder and extract it to tmp
curl -sL https://go.kubebuilder.io/dl/2.0.1/${os}/${arch} | tar -xz -C /tmp/

# move to a long-term location and put it on your path
# (you'll need to set the KUBEBUILDER_ASSETS env var if you put it somewhere else)
sudo mv /tmp/kubebuilder_2.0.1_${os}_${arch} /usr/local/kubebuilder
export PATH=$PATH:/usr/local/kubebuilder/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 $GOPATH/src/example
cd $GOPATH/src/example
kubebuilder init --domain my.domain

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.

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:"alias,omitempty"`
    
	// TLS policy of Guestbook nodes
	TLS *TLSPolicy `json:"TLS,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
	
	// GuestbookStatus is the set of Guestbook node specific statuses: Active or Standby
    GuestbookStatus GuestbookStatus `json:"guestbookStatus"`
    
    // Status of Guestbook Nodes
    Nodes []string `json:"nodes"`
}

type GuestbookStatus struct {

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

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

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 an (CR)Custom Resource for your (CRD)Custom Resource Definition 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

Next Step

Now, follow up the CronJob tutorial to better understand how it works by developing a demo example project.