operator-sdk 简单入门

创建目录

operator-sdk init operator-sdk init --project-version="2" --domain=example.com --repo=github.com/wwq-2020/crd-demo

创建模板

operator-sdk create api --group=cache --version=v1alpha1 --kind=Memcached

创建 api

operator-sdk create api --group=cache --version=v1alpha1 --kind=Memcached

修改 api/v1alpha1/memcached_types.go 中 内容,如下

// MemcachedSpec defines the desired state of Memcached
type MemcachedSpec struct {
    // +kubebuilder:validation:Minimum=0
    // Size is the size of the memcached deployment
    Size int32 `json:"size"`
}

// MemcachedStatus defines the observed state of Memcached
type MemcachedStatus struct {
    // Nodes are the names of the memcached pods
    Nodes []string `json:"nodes"`
}

// Memcached is the Schema for the memcacheds API
// +kubebuilder:subresource:status
type Memcached struct {
    metav1.TypeMeta   `json:",inline"`
    metav1.ObjectMeta `json:"metadata,omitempty"`

    Spec   MemcachedSpec   `json:"spec,omitempty"`
    Status MemcachedStatus `json:"status,omitempty"`
}

生成这个资源的代码

make generate

生成 manifests

make manifests

修改 controllers/memcached_controller.go,内容如下

/*
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package controllers

import (
    "context"
    "reflect"

    "github.com/go-logr/logr"
    appsv1 "k8s.io/api/apps/v1"
    corev1 "k8s.io/api/core/v1"
    "k8s.io/apimachinery/pkg/api/errors"
    metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    "k8s.io/apimachinery/pkg/runtime"
    "k8s.io/apimachinery/pkg/types"
    ctrl "sigs.k8s.io/controller-runtime"
    "sigs.k8s.io/controller-runtime/pkg/client"

    cachev1alpha1 "github.com/example-inc/memcached-operator/api/v1alpha1"
)

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

// +kubebuilder:rbac:groups=cache.example.com,resources=memcacheds,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups=cache.example.com,resources=memcacheds/status,verbs=get;update;patch
// +kubebuilder:rbac:groups=apps,resources=deployments,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups=core,resources=pods,verbs=get;list;

func (r *MemcachedReconciler) Reconcile(req ctrl.Request) (ctrl.Result, error) {
    ctx := context.Background()
    log := r.Log.WithValues("memcached", req.NamespacedName)

    // Fetch the Memcached instance
    memcached := &cachev1alpha1.Memcached{}
    err := r.Get(ctx, req.NamespacedName, memcached)
    if err != nil {
        if errors.IsNotFound(err) {
            // Request object not found, could have been deleted after reconcile request.
            // Owned objects are automatically garbage collected. For additional cleanup logic use finalizers.
            // Return and don't requeue
            log.Info("Memcached resource not found. Ignoring since object must be deleted")
            return ctrl.Result{}, nil
        }
        // Error reading the object - requeue the request.
        log.Error(err, "Failed to get Memcached")
        return ctrl.Result{}, err
    }

    // Check if the deployment already exists, if not create a new one
    found := &appsv1.Deployment{}
    err = r.Get(ctx, types.NamespacedName{Name: memcached.Name, Namespace: memcached.Namespace}, found)
    if err != nil && errors.IsNotFound(err) {
        // Define a new deployment
        dep := r.deploymentForMemcached(memcached)
        log.Info("Creating a new Deployment", "Deployment.Namespace", dep.Namespace, "Deployment.Name", dep.Name)
        err = r.Create(ctx, dep)
        if err != nil {
            log.Error(err, "Failed to create new Deployment", "Deployment.Namespace", dep.Namespace, "Deployment.Name", dep.Name)
            return ctrl.Result{}, err
        }
        // Deployment created successfully - return and requeue
        return ctrl.Result{Requeue: true}, nil
    } else if err != nil {
        log.Error(err, "Failed to get Deployment")
        return ctrl.Result{}, err
    }

    // Ensure the deployment size is the same as the spec
    size := memcached.Spec.Size
    if *found.Spec.Replicas != size {
        found.Spec.Replicas = &size
        err = r.Update(ctx, found)
        if err != nil {
            log.Error(err, "Failed to update Deployment", "Deployment.Namespace", found.Namespace, "Deployment.Name", found.Name)
            return ctrl.Result{}, err
        }
        // Spec updated - return and requeue
        return ctrl.Result{Requeue: true}, nil
    }

    // Update the Memcached status with the pod names
    // List the pods for this memcached's deployment
    podList := &corev1.PodList{}
    listOpts := []client.ListOption{
        client.InNamespace(memcached.Namespace),
        client.MatchingLabels(labelsForMemcached(memcached.Name)),
    }
    if err = r.List(ctx, podList, listOpts...); err != nil {
        log.Error(err, "Failed to list pods", "Memcached.Namespace", memcached.Namespace, "Memcached.Name", memcached.Name)
        return ctrl.Result{}, err
    }
    podNames := getPodNames(podList.Items)

    // Update status.Nodes if needed
    if !reflect.DeepEqual(podNames, memcached.Status.Nodes) {
        memcached.Status.Nodes = podNames
        err := r.Status().Update(ctx, memcached)
        if err != nil {
            log.Error(err, "Failed to update Memcached status")
            return ctrl.Result{}, err
        }
    }

    return ctrl.Result{}, nil
}

// deploymentForMemcached returns a memcached Deployment object
func (r *MemcachedReconciler) deploymentForMemcached(m *cachev1alpha1.Memcached) *appsv1.Deployment {
    ls := labelsForMemcached(m.Name)
    replicas := m.Spec.Size

    dep := &appsv1.Deployment{
        ObjectMeta: metav1.ObjectMeta{
            Name:      m.Name,
            Namespace: m.Namespace,
        },
        Spec: appsv1.DeploymentSpec{
            Replicas: &replicas,
            Selector: &metav1.LabelSelector{
                MatchLabels: ls,
            },
            Template: corev1.PodTemplateSpec{
                ObjectMeta: metav1.ObjectMeta{
                    Labels: ls,
                },
                Spec: corev1.PodSpec{
                    Containers: []corev1.Container{{
                        Image:   "memcached:1.4.36-alpine",
                        Name:    "memcached",
                        Command: []string{"memcached", "-m=64", "-o", "modern", "-v"},
                        Ports: []corev1.ContainerPort{{
                            ContainerPort: 11211,
                            Name:          "memcached",
                        }},
                    }},
                },
            },
        },
    }
    // Set Memcached instance as the owner and controller
    ctrl.SetControllerReference(m, dep, r.Scheme)
    return dep
}

// labelsForMemcached returns the labels for selecting the resources
// belonging to the given memcached CR name.
func labelsForMemcached(name string) map[string]string {
    return map[string]string{"app": "memcached", "memcached_cr": name}
}

// getPodNames returns the pod names of the array of pods passed in
func getPodNames(pods []corev1.Pod) []string {
    var podNames []string
    for _, pod := range pods {
        podNames = append(podNames, pod.Name)
    }
    return podNames
}

func (r *MemcachedReconciler) SetupWithManager(mgr ctrl.Manager) error {
    return ctrl.NewControllerManagedBy(mgr).
        For(&cachev1alpha1.Memcached{}).
        Owns(&appsv1.Deployment{}).
        Complete(r)
}

生成 manifests

make manifests

注册到 apiserver

make install

在 k8s 外部运行

make run ENABLE_WEBHOOKS=false

在 k8s 内运行

make docker-build IMG=memcached-operator:v0.0.1
cd config/default/ && kustomize edit set namespace "default" && cd ../..
make deploy IMG=memcached-operator:v0.0.1

修改 config/samples/cache_v1alpha1_memcached.yaml 中内容

spec:
  # Add fields here
  size: 3