Repurika is a Kubernetes Custom Resource works like ReplicaSet, an Kubernetes Native Resource. Repurika is developed using Kubebuilder, for Education purpose.

The improved version of Repurika is Seika

Install the CRD to Kubernetes System:

$ kubectl apply -f dist/install.yaml

Apply a Repurika (likes ReplicaSet)

$ cat dist/shuka-no-repurika.yaml
apiVersion: batch.bonavadeur.io/v1
kind: Repurika
metadata:
  labels:
    app.kubernetes.io/name: repurika
    app.kubernetes.io/instance: repurika-sample
    app.kubernetes.io/part-of: repurika
    app.kubernetes.io/managed-by: kustomize
    app.kubernetes.io/created-by: repurika
  name: shuka-no-repurika
spec:
  size: 2
  selector:
    matchLabels:
      app: shuka
  template:
    metadata:
      labels:
        app: shuka
    spec:
      containers:
      - name: shuka
        image: docker.io/bonavadeur/shuka:sleep

$ kubectl apply -f dist/shuka-no-repurika.yaml
repurika.batch.bonavadeur.io/shuka-no-repurika created

$ kubectl get pod | grep repurika
shuka-no-repurika-ytp55        1/1     Running   0              4m45s
shuka-no-repurika-zqu4h        1/1     Running   0              4m45s

Delete one shuka-no-repurika-*, you can see one more pod is created

Install Kubebuilder arcording site: Kubebuilder Quick Start

Scaffolding Out Our Project

# create a project directory, and then run the init command.
mkdir repurika
cd repurika
# scaffolding project
kubebuilder init --domain tesuto.bonavadeur.io --repo {your_repo}

Create atarashii API

kubebuilder create api --group batch --version v1 --kind Repurika

Define type in api/v1/repurika_types.go. Note that the field RepurikaSpec.Template.Metadata may be not embedded (don't worry about you do not understand this), means that you cannot apply the .yaml file with field .spec.template.metadata. Solution will be presented in following steps. Don't worry, I am here ^^.

Implement the Controller like file internal/controller/repurika_controller.go

In this Project, I used my library for logging named bonalib, located in internal/bonalib, so I didn't use default library. To disable logging of default library, change this in cmd/main.go

opts := zap.Options{
    Development: true,
    Level:       zapcore.Level(3),
}

Whenever you change *_types.go file, you need to regenerate code by:

make generate

To generate manifest:

make manifests

Install CRD in Kubernetes system:

make install

In install step, you may be encounter error

The CustomResourceDefinition "repurikas.batch.bonavadeur.io" is invalid: metadata.annotations: Too long: must have at most 262144 bytes

Let's change Makefile, in PHONY manifests, add crd:maxDescLen=0 option

.PHONY: manifests
manifests: controller-gen
	$(CONTROLLER_GEN) rbac:roleName=manager-role crd:maxDescLen=0 webhook paths="./..." output:crd:artifacts:config=config/crd/bases

Uninstall CRD:

make uninstall

Run controller locally:

make run

Apply an instance of Custom Resource

kubectl apply -f config/samples/batch_v1_repurika.yaml

You can encounter an error in this step.

Error from server (BadRequest): error when creating "config/samples/batch_v1_repurika.yaml": Repurika in version "v1" cannot be handled as a Repurika: strict decoding error: unknown field "spec.template.metadata.labels"

Let's enable embedded field in Makefile. Change PHONY manifests agains:

.PHONY: manifests
manifests: controller-gen
	$(CONTROLLER_GEN) rbac:roleName=manager-role crd:maxDescLen=0,generateEmbeddedObjectMeta=true webhook paths="./..." output:crd:artifacts:config=config/crd/bases

This is the final version of Makefile :). Trust me!

Then, you can see colorful logging from terminal running make run command!

Build image. Make sure that you have access to the Docker Repo

make docker-build docker-push docker.io/bonavadeur/repurika:latest
# change repo by yours, use full repo domain, include "docker.io", kudasai onegaishimasu.

You can deploy it now

make deploy IMG=docker.io/bonavadeur/repurika:latest

Chotto matte kudasai!!! Your product may be not work correctly! After you run make deploy command, your Kubernetes has a CR named repurika and you can list all repurika instance by command kubectl get repurika. But when apply a repurika instance, no Pod is created. Logging container manager in Pod repurika-controll-manager in namespace repurika-system you can see error:

pkg/mod/k8s.io/[email protected]/tools/cache/reflector.go:229: failed to list *v1.Pod: pods is forbidden: User "system:serviceaccount:repurika-system:repurika-controller-manager" cannot list resource "pods" in API group "" at the cluster scope

It means that your controller has no permission to list all Pods in Kubernetes system. Back to internal/controller/repurika_controller.go and add some markers:

type RepurikaReconciler struct {
	client.Client
	Scheme *runtime.Scheme
}

//+kubebuilder:rbac:groups=batch.bonavadeur.io,resources=repurikas,verbs=get;list;watch;create;update;patch;delete
//+kubebuilder:rbac:groups=batch.bonavadeur.io,resources=repurikas/status,verbs=get;update;patch
//+kubebuilder:rbac:groups=batch.bonavadeur.io,resources=repurikas/finalizers,verbs=update
//+kubebuilder:rbac:groups=core,resources=pods,verbs=get;list;watch;create;update;patch;delete
//+kubebuilder:rbac:groups=core,resources=pods/status,verbs=get

Now, generate the installer file and bring it out over the World! Ikimashou!!!

make build-installer IMG=docker.io/bonavadeur/repurika:latest

Your installer file locate in dist/install.yaml

I hope that this is a small tutorial beside the tutorial on Kuberbuilder Book. Repurika is surely not a perfectly Kubebuilder Project. But I hope that it is useful for beginner (like me).

Any improvement can be sent to me, via [email protected], or create a new issues

Đào Hiệp - Bonavadeur - ボナちゃん
The Future Internet Laboratory, E711 C7 Building, Hanoi University of Science and Technology, Vietnam. 未来のインターネット研究室, C7 の E ７１１、ハノイ百科大学、ベトナム。