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@domac
domac committed Mar 8, 2020
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# crddemo : Kubernetes 自定义控制器Demo例子

----

## 基本目录结构

Expand Down Expand Up @@ -96,4 +95,148 @@ k8s.io/client-go/tools/record
command-line-arguments
go clean -i
... ...
```
```

## 执行程序文件

把crddemo放到kubernetes集群中，或者本地也行，只要能访问到apiserver和具备kubeconfig

可以看到，程序运行的时候，一开始会报错。这是因为，此时 Mydemo 对象的 CRD 还没有被创建出来，所以 Informer 去 APIServer 里获取 Mydemos 对象时，并不能找到 Mydemo 这个 API 资源类型的定义

```
$ ./crddemo --kubeconfig=/data/svr/projects/kubernetes/config/kubectl.kubeconfig --master=http://127.0.0.1:8080 -alsologtostderr=true
I0308 12:23:18.494507 27426 controller.go:79] Setting up mydemo event handlers
I0308 12:23:18.494829 27426 controller.go:105] Starting Mydemo control loop
I0308 12:23:18.494840 27426 controller.go:108] Waiting for informer caches to sync
E0308 12:23:18.496902 27426 reflector.go:178] github.com/domac/crddemo/pkg/client/informers/externalversions/factory.go:117: Failed to list *v1.Mydemo: the server could not find the requested resource (get mydemos.crddemo.k8s.io)
E0308 12:23:18.497477 27426 reflector.go:178] github.com/domac/crddemo/pkg/client/informers/externalversions/factory.go:117: Failed to list *v1.Mydemo: the server could not find the requested resource (get mydemos.crddemo.k8s.io)
E0308 12:23:21.604508 27426 reflector.go:178] github.com/domac/crddemo/pkg/client/informers/externalversions/factory.go:117: Failed to list *v1.Mydemo: the server could not find the requested resource (get mydemos.crddemo.k8s.io)
E0308 12:23:26.932293 27426 reflector.go:178] github.com/domac/crddemo/pkg/client/informers/externalversions/factory.go:117: Failed to list *v1.Mydemo: the server could not find the requested resource (get mydemos.crddemo.k8s.io)
... ...
```

接下来，我们执行我们自定义资源的定义文件：

```yaml
apiVersion: apiextensions.k8s.io/v1beta1
kind: CustomResourceDefinition
metadata:
name: mydemos.crddemo.k8s.io
spec:
group: crddemo.k8s.io
version: v1
names:
kind: Mydemo
plural: mydemos
scope: Namespaced
```

执行创建

```
$ kubectl apply -f crd/mydemo.yaml
customresourcedefinition.apiextensions.k8s.io/mydemos.crddemo.k8s.io created
```

此时，观察crddemo的日志输出，可以看到Controller的日志恢复了正常，控制循环启动成功

```
I0308 12:30:29.956263 28282 controller.go:113] Starting workers
I0308 12:30:29.956307 28282 controller.go:118] Started workers
```

然后，我们可以对我们的Mydemo对象进行增删改查操作了。

首先，新建一个自定义资源对象

example-mydemo.yaml

```yaml
apiVersion: crddemo.k8s.io/v1
kind: Mydemo
metadata:
name: example-mydemo
spec:
ip: "127.0.0.1"
port: 8080
```

执行创建

```
$ kubectl apply -f example-mydemo.yaml
mydemo.crddemo.k8s.io/example-mydemo created
```

创建成功够，看k8s集群是否成功存储起来

```
$ kubectl get Mydemo
NAME AGE
example-mydemo 2s
```

这时候，查看一下控制器的输出：

```
I0308 12:31:24.983663 28282 controller.go:216] [DemoCRD] Try to process mydemo: &v1.Mydemo{TypeMeta:v1.TypeMeta{Kind:"", APIVersion:""}, ObjectMeta:v1.ObjectMeta{Name:"example-mydemo", GenerateName:"", Namespace:"default", SelfLink:"/apis/crddemo.k8s.io/v1/namespaces/default/mydemos/example-mydemo", UID:"8a6d17f7-17f3-4a1d-8250-bb092678ae7e", ResourceVersion:"10818363", Generation:1, CreationTimestamp:v1.Time{Time:time.Time{wall:0x0, ext:63719238684, loc:(*time.Location)(0x1e566c0)}}, DeletionTimestamp:(*v1.Time)(nil), DeletionGracePeriodSeconds:(*int64)(nil), Labels:map[string]string(nil), Annotations:map[string]string{"kubectl.kubernetes.io/last-applied-configuration":"{\"apiVersion\":\"crddemo.k8s.io/v1\",\"kind\":\"Mydemo\",\"metadata\":{\"annotations\":{},\"name\":\"example-mydemo\",\"namespace\":\"default\"},\"spec\":{\"ip\":\"127.0.0.1\",\"port\":8080}}\n"}, OwnerReferences:[]v1.OwnerReference(nil), Finalizers:[]string(nil), ClusterName:"", ManagedFields:[]v1.ManagedFieldsEntry(nil)}, Spec:v1.MydemoSpec{Ip:"127.0.0.1", Port:8080}} ...
I0308 12:31:24.983844 28282 controller.go:174] Successfully synced 'default/example-mydemo'
I0308 12:31:24.983893 28282 event.go:278] Event(v1.ObjectReference{Kind:"Mydemo", Namespace:"default", Name:"example-mydemo", UID:"8a6d17f7-17f3-4a1d-8250-bb092678ae7e", APIVersion:"crddemo.k8s.io/v1", ResourceVersion:"10818363", FieldPath:""}): type: 'Normal' reason: 'Synced' Mydemo synced successfully
```

可以看到，我们上面创建 example-mydemo.yaml 的操作，触发了 EventHandler 的`添加`事件，从而被放进了工作队列。紧接着，控制循环就从队列里拿到了这个对象，并且打印出了正在`处理`这个 Mydemo 对象的日志。


我们这时候，尝试修改资源，对对应的port属性进行修改

```yaml
apiVersion: crddemo.k8s.io/v1
kind: Mydemo
metadata:
name: example-mydemo
spec:
ip: "127.0.0.1"
port: 9090
```

手段执行修改

```
$ kubectl apply -f example-mydemo.yaml
```

此时，crddemo新增出来的日志如下：

```
I0308 12:32:05.663044 28282 controller.go:216] [DemoCRD] Try to process mydemo: &v1.Mydemo{TypeMeta:v1.TypeMeta{Kind:"", APIVersion:""}, ObjectMeta:v1.ObjectMeta{Name:"example-mydemo", GenerateName:"", Namespace:"default", SelfLink:"/apis/crddemo.k8s.io/v1/namespaces/default/mydemos/example-mydemo", UID:"8a6d17f7-17f3-4a1d-8250-bb092678ae7e", ResourceVersion:"10818457", Generation:2, CreationTimestamp:v1.Time{Time:time.Time{wall:0x0, ext:63719238684, loc:(*time.Location)(0x1e566c0)}}, DeletionTimestamp:(*v1.Time)(nil), DeletionGracePeriodSeconds:(*int64)(nil), Labels:map[string]string(nil), Annotations:map[string]string{"kubectl.kubernetes.io/last-applied-configuration":"{\"apiVersion\":\"crddemo.k8s.io/v1\",\"kind\":\"Mydemo\",\"metadata\":{\"annotations\":{},\"name\":\"example-mydemo\",\"namespace\":\"default\"},\"spec\":{\"ip\":\"127.0.0.1\",\"port\":9080}}\n"}, OwnerReferences:[]v1.OwnerReference(nil), Finalizers:[]string(nil), ClusterName:"", ManagedFields:[]v1.ManagedFieldsEntry(nil)}, Spec:v1.MydemoSpec{Ip:"127.0.0.1", Port:9080}} ...
I0308 12:32:05.663179 28282 controller.go:174] Successfully synced 'default/example-mydemo'
I0308 12:32:05.663208 28282 event.go:278] Event(v1.ObjectReference{Kind:"Mydemo", Namespace:"default", Name:"example-mydemo", UID:"8a6d17f7-17f3-4a1d-8250-bb092678ae7e", APIVersion:"crddemo.k8s.io/v1", ResourceVersion:"10818457", FieldPath:""}): type: 'Normal' reason: 'Synced' Mydemo synced successfully
```

可以看到，这一次，Informer 注册的“更新”事件被触发，更新后的 Mydemo 对象的 Key 被添加到了工作队列之中。

所以，接下来控制循环从工作队列里拿到的 Mydemo 对象，与前一个对象是不同的：它的 ResourceVersion 的值从 10818363 变成了 10818457 ；而 Spec 里的Port字段，则变成了 9080。最后，我再把这个对象删除掉：

```
$ kubectl delete -f example-mydemo.yaml
mydemo.crddemo.k8s.io "example-mydemo" deleted
```


这一次，在控制器的输出里，我们就可以看到，Informer 注册的“删除”事件被触发,输出如下：

```
W0308 12:33:08.494755 28282 controller.go:203] DemoCRD: default/example-mydemo does not exist in local cache, will delete it from Mydemo ...
I0308 12:33:08.495793 28282 controller.go:206] [DemoCRD] Deleting mydemo: default/example-mydemo ...
I0308 12:33:08.495808 28282 controller.go:174] Successfully synced 'default/example-mydemo'
```
然后，k8s集群的资源也被清除了：

```
$ kubectl get Mydemo
No resources found in default namespace.
```

以上，就是编写和使用自定义控制器的全部流程了。

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