在RC中需要動態調整叢集數量，使用PodControlInterface來實現Pod的增刪基本操作。

// PodControlInterface is an interface that knows how to add or delete pods
// created as an interface to allow testing.
type PodControlInterface interface {
	// CreatePods creates new pods according to the spec.
	CreatePods(namespace string, template *v1.PodTemplateSpec, object runtime.Object) error
	// CreatePodsOnNode creates a new pod according to the spec on the specified node,
	// and sets the ControllerRef.
	CreatePodsOnNode(nodeName, namespace string, template *v1.PodTemplateSpec, object runtime.Object, controllerRef *metav1.OwnerReference) error
	// CreatePodsWithControllerRef creates new pods according to the spec, and sets object as the pod's controller.
	CreatePodsWithControllerRef(namespace string, template *v1.PodTemplateSpec, object runtime.Object, controllerRef *metav1.OwnerReference) error
	// DeletePod deletes the pod identified by podID.
	DeletePod(namespace string, podID string, object runtime.Object) error
	// PatchPod patches the pod.
	PatchPod(namespace, name string, data []byte) error
}
 

介面實現如下：

// RealPodControl is the default implementation of PodControlInterface.
type RealPodControl struct {
	KubeClient clientset.Interface
	Recorder   record.EventRecorder
}

以CreatePodsOnNode為例，在某一個指定的Node節點上建立一個Pod

// CreatePodsOnNode creates a new pod according to the spec on the specified node,
	// and sets the ControllerRef.
	CreatePodsOnNode(nodeName, namespace string, template *v1.PodTemplateSpec, object runtime.Object, controllerRef *metav1.OwnerReference) error
 

func (r RealPodControl) CreatePodsOnNode(nodeName, namespace string, template *v1.PodTemplateSpec, object runtime.Object, controllerRef *metav1.OwnerReference) error {
	if err := validateControllerRef(controllerRef); err != nil {
		return err
	}
	return r.createPods(nodeName, namespace, template, object, controllerRef)
}
 

從模板物件中獲取Pod物件

func GetPodFromTemplate(template *v1.PodTemplateSpec, parentObject runtime.Object, controllerRef *metav1.OwnerReference) (*v1.Pod, error)

建立方法是通過KubeClient實現的

 newPod, err := r.KubeClient.CoreV1().Pods(namespace).Create(pod)

程式碼路徑：client-go/kubernetes/typed/core/v1/pod.go

// PodInterface has methods to work with Pod resources.
type PodInterface interface {
	Create(*v1.Pod) (*v1.Pod, error)
	Update(*v1.Pod) (*v1.Pod, error)
	UpdateStatus(*v1.Pod) (*v1.Pod, error)
	Delete(name string, options *metav1.DeleteOptions) error
	DeleteCollection(options *metav1.DeleteOptions, listOptions metav1.ListOptions) error
	Get(name string, options metav1.GetOptions) (*v1.Pod, error)
	List(opts metav1.ListOptions) (*v1.PodList, error)
	Watch(opts metav1.ListOptions) (watch.Interface, error)
	Patch(name string, pt types.PatchType, data []byte, subresources ...string) (result *v1.Pod, err error)
	PodExpansion
}

// Create takes the representation of a pod and creates it.  Returns the server's representation of the pod, and an error, if there is any.
func (c *pods) Create(pod *v1.Pod) (result *v1.Pod, err error) {
	result = &v1.Pod{}
	err = c.client.Post().
		Namespace(c.ns).
		Resource("pods").
		Body(pod).
		Do().
		Into(result)
	return
}

由RESTClient來實現

// Interface captures the set of operations for generically interacting with Kubernetes REST apis.
type Interface interface {
	GetRateLimiter() flowcontrol.RateLimiter
	Verb(verb string) *Request
	Post() *Request
	Put() *Request
	Patch(pt types.PatchType) *Request
	Get() *Request
	Delete() *Request
	APIVersion() schema.GroupVersion
}

呼叫Post方法

// Post begins a POST request. Short for c.Verb("POST").
func (c *RESTClient) Post() *Request {
	return c.Verb("POST")
}

func (c *RESTClient) Verb(verb string) *Request {
	backoff := c.createBackoffMgr()

	if c.Client == nil {
		return NewRequest(nil, verb, c.base, c.versionedAPIPath, c.contentConfig, c.serializers, backoff, c.Throttle, 0)
	}
	return NewRequest(c.Client, verb, c.base, c.versionedAPIPath, c.contentConfig, c.serializers, backoff, c.Throttle, c.Client.Timeout)
}

建立request物件

// NewRequest creates a new request helper object for accessing runtime.Objects on a server.
func NewRequest(client HTTPClient, verb string, baseURL *url.URL, versionedAPIPath string, content ContentConfig, serializers Serializers, backoff BackoffManager, throttle flowcontrol.RateLimiter, timeout time.Duration) *Request {
	

呼叫Do方法

func (r *Request) Do() Result {
	r.tryThrottle()

	var result Result
	err := r.request(func(req *http.Request, resp *http.Response) {
		result = r.transformResponse(resp, req)
	})
	if err != nil {
		return Result{err: err}
	}
	return result
}

Request物件

/ Request allows for building up a request to a server in a chained fashion.
// Any errors are stored until the end of your call, so you only have to
// check once.
type Request struct {
	// required
	client HTTPClient
	verb   string

	baseURL     *url.URL
	content     ContentConfig
	serializers Serializers

HTTPClient物件

// HTTPClient is an interface for testing a request object.
type HTTPClient interface {
	Do(req *http.Request) (*http.Response, error)
}

http.Request物件由基本類實現C:/Go/src/net/http/request.go

由上可知，建立Pod的核心方法是傳送Post請求到apiserver,

err = c.client.Post().
		Namespace(c.ns).
		Resource("pods").
		Body(pod).
		Do().
		Into(result)