Memcached Operator Example built using Kubebuilder

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Table of Contents

• Memcached Operator Example built using Kubebuilder
• Overview
• Prerequisites
• Getting Started
  • Cloning the repository
  • [Optional] Minishift installation and setup
  • Installing as standalone
  • Verifying
  • Uninstalling
• Quick Start Kubebuilder
• Contributing

Overview

IMPORTANT This project is deprecated and has no longer been maintained.

Simple example over how to know how getting started with Kubebuilder

Prerequisites

Install Golang v1.12+

Ensure the $GOPATH environment variable is set

Install kubectl

Access to a Kubernetes v1.11.3+ cluster

kubebuilder

Getting Started

Cloning the repository

By the following commands you will create a local directory and clone this project.

$ git clone git@github.com:dev4devs-com/memcached-kubebuilder.git $GOPATH/src/github.com/dev4devs-com/memcached-kubebuilder

[Optional] Minishift installation and setup

Install Minishift then enable Operators on it by running the following commands.

# create a new profile to test the operator
$ minishift profile set operator

# enable the admin-user add-on
$ minishift addon enable admin-user

# add insecure registry to download the images from docker
$ minishift config set insecure-registry 172.30.0.0/16

# start the instance
$ minishift start

❗	Please, feel free to use Minikube your any Kubernetes cluster as you wish.

Installing as standalone

Use the following command to install the Operator(Manager) and the Memcached example CR.

ℹ️	To install you need be logged in as a user with cluster privileges like the system:admin user. E.g. By using: oc login -u system:admin.

$ make app/install

Verifying

To verify that the installation was successful completed you can check the deployment.apps/controller-manager and deployment.apps/memcached-sample were created and are running. Following an example of the expected result when all is applied.

 $ kubectl get all
NAME                                     READY   STATUS    RESTARTS   AGE
pod/controller-manager-bd74bb8f8-dvgxc   1/1     Running   0          14m
pod/memcached-sample-7484db9bc9-88bh8    1/1     Running   0          13m


NAME                                         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)     AGE
service/controller-manager-metrics-service   ClusterIP   172.30.161.134   <none>        8443/TCP    14m
service/memcached-sample                     ClusterIP   172.30.148.254   <none>        11211/TCP   13m


NAME                                 DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/controller-manager   1         1         1            1           14m
deployment.apps/memcached-sample     1         1         1            1           13m

NAME                                           DESIRED   CURRENT   READY   AGE
replicaset.apps/controller-manager-bd74bb8f8   1         1         1       14m
replicaset.apps/memcached-sample-7484db9bc9    1         1         1       13m

Uninstalling

Use the following command will delete all since it will remove the namespace where all was installed.

$ make app/uninstal

ℹ️	To uninstall you need be logged in as a user with cluster privileges like the system:admin user. E.g. By using: oc login -u system:admin.

Quick Start Kubebuilder

Following the steps used to create this project

• To create the project

$ mkdir mkdir memcached-kubebuilder
$ cd memcached-kubebuilder/
$ kubebuilder init --domain example.com Memcached
#Select the options y and y

• To create the APIs and controllerr

$ kubebuilder create api --group memcached --version v1 --kind Memcached #Select the options y and y

• Update the api/v1/memcached_types.go as follows to add the specs and status

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

    //Quantity of instances
    Size int32 `json:"size"`
}

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

    //Status of pods
    Nodes []string `json:"nodes"`
}

• Run the command make in the root of the project to update the deepcopy files.

• Add the implementation in the Memcached controllers/memcached_controller.go

• Change the MemcachedReconciler Struct in order to pass the schema as follows.

// MemcachedReconciler reconciles a Memcached object
type MemcachedReconciler struct {
    client.Client
    Log logr.Logger
    *runtime.Scheme
}

• Add the schema to the MemcachedReconciler in the main.go as follows.

if err = (&controllers.MemcachedReconciler{
    Client: mgr.GetClient(),
    Log:    ctrl.Log.WithName("controllers").WithName("Memcached"),
    Scheme: mgr.GetScheme(), // todo check because was required to add it to set the owner
}).SetupWithManager(mgr); err != nil {
    setupLog.Error(err, "unable to create controller", "controller", "Memcached")
    os.Exit(1)
}

• Remove from the command generate in the Makefile the instrutions to update the roles.

• Add the instrutions to install/unistall the project in the Makefile as follows.

.PHONY: app/install
app/install:
    - kubectl apply -f config/manager/manager.yaml
    - kubectl apply -f config/crd/bases/memcached.example.com_memcacheds.yaml -n system
    - kubectl apply -f config/samples/memcached_v1_memcached.yaml -n system
    - kubectl apply -f config/rbac/ -n system

.PHONY: app/uninstall
app/uninstall:
    - kubectl delete namespace system

• Add the serviceAccount in the config/rbac/service_account.yaml as follows.

apiVersion: v1
kind: ServiceAccount
metadata:
  name: default

• Replace the Roles in config/rbac/role.yaml as follows.

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  creationTimestamp: null
  name: manager-role
rules:
- apiGroups:
  - ""
  resources:
  - pods
  - services
  - endpoints
  - persistentvolumeclaims
  - events
  - configmaps
  - secrets
  verbs:
  - '*'
- apiGroups:
  - ""
  resources:
  - namespaces
  verbs:
  - get
- apiGroups:
  - memcached.example.com
  resources:
  - memcacheds
  verbs:
  - create
  - delete
  - get
  - list
  - patch
  - update
  - watch
- apiGroups:
  - apps
  resources:
  - deployments
  - daemonsets
  - replicasets
  - statefulsets
  verbs:
  - '*'
- apiGroups:
  - apps
  resourceNames:
  - controller-manager
  resources:
  - deployments/finalizers
  verbs:
  - update
- apiGroups:
  - memcached.example.com
  resources:
  - '*'
  verbs:
  - '*'

• Update the IMG in the Makefile with your repository and image:tag as you wish. E.g quay.io/dev4devs-com/memcached-kubebuilder:latest

• Run in the root of the project make docker-build

• Run in the root of the project make docker-push

ℹ️	You need perform the login into your regestry locally for the docker-push command be able to push the image to it.

• Update the memcached-kubebuilder/controllers/memcached_controller.go with the image:tag created and pushed

• Ensure that the image was pushed and your cluster is able to pull it.

ℹ️	Just for tests purposes make the image public and setting up the cluster to allow use insecure registry. ( E.g --insecure-registry 172.30.0.0/16 )

❗	See that the Watches were not implemented in this example so far.

• Now, you are able to test it. Run make app/install. Note that as result of it you should be able to check 1 pod running for the operator manager and another one for the Memcached.

Contributing

All contributions are hugely appreciated. Please see our Contribution Guide for guidelines on how to open issues and pull requests. Please check out our Code of Conduct too.