kubelet/rkt: Add PullImage()/IsImagePresent() to rkt runtime.

pkg/kubelet/rkt/pull.go

@@ -0,0 +1,110 @@
+/*
+Copyright 2015 Google Inc. 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 rkt
+
+import (
+	"fmt"
+	"os"
+	"path"
+	"strings"
+
+	"github.com/docker/docker/pkg/parsers"
+	docker "github.com/fsouza/go-dockerclient"
+	"github.com/golang/glog"
+)
+
+const (
+	authDir            = "auth.d"
+	dockerAuthTemplate = `{"rktKind":"dockerAuth","rktVersion":"v1","registries":[%q],"credentials":{"user":%q,"password":%q}}`
+)
+
+// writeDockerAuthConfig writes the docker credentials to rkt auth config files.
+// This enables rkt to pull docker images from docker registry with credentials.
+func (r *Runtime) writeDockerAuthConfig(image string, creds docker.AuthConfiguration) error {
+	registry := "index.docker.io"
+	// Image spec: [<registry>/]<repository>/<image>[:<version]
+	explicitRegistry := (strings.Count(image, "/") == 2)
+	if explicitRegistry {
+		registry = strings.Split(image, "/")[0]
+	}
+
+	localConfigDir := rktLocalConfigDir
+	if r.config.LocalConfigDir != "" {
+		localConfigDir = r.config.LocalConfigDir
+	}
+	authDir := path.Join(localConfigDir, "auth.d")
+	if _, err := os.Stat(authDir); os.IsNotExist(err) {
+		if err := os.Mkdir(authDir, 0600); err != nil {
+			glog.Errorf("rkt: Cannot create auth dir: %v", err)
+			return err
+		}
+	}
+	f, err := os.Create(path.Join(localConfigDir, authDir, registry+".json"))
+	if err != nil {
+		glog.Errorf("rkt: Cannot create docker auth config file: %v", err)
+		return err
+	}
+	defer f.Close()
+	config := fmt.Sprintf(dockerAuthTemplate, registry, creds.Username, creds.Password)
+	if _, err := f.Write([]byte(config)); err != nil {
+		glog.Errorf("rkt: Cannot write docker auth config file: %v", err)
+		return err
+	}
+	return nil
+}
+
+// PullImage invokes 'rkt fetch' to download an aci.
+func (r *Runtime) PullImage(img string) error {
+	// Use credentials for docker images. This string operation can be cleaned up
+	// once the format of image is landed, see:
+	// https://github.com/GoogleCloudPlatform/kubernetes/issues/7203
+	//
+	if strings.HasPrefix(img, dockerPrefix) {
+		repoToPull, tag := parsers.ParseRepositoryTag(img)
+		// If no tag was specified, use the default "latest".
+		if len(tag) == 0 {
+			tag = "latest"
+		}
+
+		creds, ok := r.dockerKeyring.Lookup(repoToPull)
+		if !ok {
+			glog.V(1).Infof("Pulling image %s without credentials", img)
+		}
+
+		// Let's update a json.
+		// TODO(yifan): Find a way to feed this to rkt.
+		if err := r.writeDockerAuthConfig(img, creds); err != nil {
+			return err
+		}
+	}
+
+	output, err := r.runCommand("fetch", img)
+	if err != nil {
+		return fmt.Errorf("rkt: Failed to fetch image: %v:", output)
+	}
+	return nil
+}
+
+// IsImagePresent returns true if the image is available on the machine.
+// TODO(yifan): 'rkt image' is now landed on master, use that once we bump up
+// the rkt version.
+func (r *Runtime) IsImagePresent(img string) (bool, error) {
+	if _, err := r.runCommand("prepare", "--local=true", img); err != nil {
+		return false, nil
+	}
+	return true, nil
+}

pkg/kubelet/rkt/rkt.go

@@ -58,10 +58,6 @@ const (
 	Garbage        = "garbage"
 )
 
-const (
-	dockerAuthTemplate = `{"rktKind":"dockerAuth","rktVersion":"v1","registries":[%q],"credentials":{"user":%q,"password":%q}}`
-)
-
 // Runtime implements the ContainerRuntime for rkt. The implementation
 // uses systemd, so in order to run this runtime, systemd must be installed
 // on the machine.