kubelet: refactor kubelet.Runtimehooks to container.ImagePuller.

pkg/kubelet/container/image_puller.go

@@ -0,0 +1,104 @@
+/*
+Copyright 2015 The Kubernetes Authors All rights reserved.
+
+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 container
+
+import (
+	"fmt"
+
+	"github.com/golang/glog"
+	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/client/record"
+)
+
+// imagePuller pulls the image using Runtime.PullImage().
+// It will check the presence of the image, and report the 'image pulling',
+// 'image pulled' events correspondingly.
+type imagePuller struct {
+	recorder record.EventRecorder
+	runtime  Runtime
+}
+
+// NewImagePuller takes an event recorder and container runtime to create a
+// image puller that wraps the container runtime's PullImage interface.
+func NewImagePuller(recorder record.EventRecorder, runtime Runtime) ImagePuller {
+	return &imagePuller{
+		recorder: recorder,
+		runtime:  runtime,
+	}
+}
+
+// shouldPullImage returns whether we should pull an image according to
+// the presence and pull policy of the image.
+func shouldPullImage(container *api.Container, imagePresent bool) bool {
+	if container.ImagePullPolicy == api.PullNever {
+		return false
+	}
+
+	if container.ImagePullPolicy == api.PullAlways ||
+		(container.ImagePullPolicy == api.PullIfNotPresent && (!imagePresent)) {
+		return true
+	}
+
+	return false
+}
+
+// reportImagePull reports 'image pulling', 'image pulled' or 'image pulling failed' events.
+func (puller *imagePuller) reportImagePull(ref *api.ObjectReference, event string, image string, pullError error) {
+	if ref == nil {
+		return
+	}
+
+	switch event {
+	case "pulling":
+		puller.recorder.Eventf(ref, "pulling", "Pulling image %q", image)
+	case "pulled":
+		puller.recorder.Eventf(ref, "pulled", "Successfully pulled image %q", image)
+	case "failed":
+		puller.recorder.Eventf(ref, "failed", "Failed to pull image %q: %v", image, pullError)
+	}
+}
+
+// PullImage pulls the image for the specified pod and container.
+func (puller *imagePuller) PullImage(pod *api.Pod, container *api.Container, pullSecrets []api.Secret) error {
+	ref, err := GenerateContainerRef(pod, container)
+	if err != nil {
+		glog.Errorf("Couldn't make a ref to pod %v, container %v: '%v'", pod.Name, container.Name, err)
+	}
+	spec := ImageSpec{container.Image}
+	present, err := puller.runtime.IsImagePresent(spec)
+	if err != nil {
+		if ref != nil {
+			puller.recorder.Eventf(ref, "failed", "Failed to inspect image %q: %v", container.Image, err)
+		}
+		return fmt.Errorf("failed to inspect image %q: %v", container.Image, err)
+	}
+
+	if !shouldPullImage(container, present) {
+		if present && ref != nil {
+			puller.recorder.Eventf(ref, "pulled", "Container image %q already present on machine", container.Image)
+		}
+		return nil
+	}
+
+	puller.reportImagePull(ref, "pulling", container.Image, nil)
+	if err = puller.runtime.PullImage(spec, pullSecrets); err != nil {
+		puller.reportImagePull(ref, "failed", container.Image, err)
+		return err
+	}
+	puller.reportImagePull(ref, "pulled", container.Image, nil)
+	return nil
+}

pkg/kubelet/container/runtime.go

@@ -100,17 +100,11 @@ type ContainerCommandRunner interface {
 	PortForward(pod *Pod, port uint16, stream io.ReadWriteCloser) error
 }
 
-// Customizable hooks injected into container runtimes.
-type RuntimeHooks interface {
-	// Determines whether the runtime should pull the specified container's image.
-	ShouldPullImage(pod *api.Pod, container *api.Container, imagePresent bool) bool
-
-	// Runs when we start to pull an image.
-	ReportImagePulling(pod *api.Pod, container *api.Container)
-
-	// Runs after an image is pulled reporting its status. Error may be nil
-	// for a successful pull.
-	ReportImagePulled(pod *api.Pod, container *api.Container, err error)
+// ImagePuller wraps Runtime.PullImage() to pull a container image.
+// It will check the presence of the image, and report the 'image pulling',
+// 'image pulled' events correspondingly.
+type ImagePuller interface {
+	PullImage(pod *api.Pod, container *api.Container, pullSecrets []api.Secret) error
 }
 
 // Pod is a group of containers, with the status of the pod.