add rados block device(rbd) volume plugin

Signed-off-by: Huamin Chen <hchen@redhat.com>

pkg/volume/rbd/rbd_util.go

@@ -0,0 +1,140 @@
+/*
+Copyright 2014 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.
+*/
+
+//
+// utility functions to setup rbd volume
+// mainly implement diskManager interface
+//
+
+package rbd
+
+import (
+	"errors"
+	"fmt"
+	"math/rand"
+	"os"
+	"path"
+	"strings"
+	"time"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/util/mount"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/volume"
+	"github.com/golang/glog"
+)
+
+// stat a path, if not exists, retry maxRetries times
+func waitForPathToExist(devicePath string, maxRetries int) bool {
+	for i := 0; i < maxRetries; i++ {
+		_, err := os.Stat(devicePath)
+		if err == nil {
+			return true
+		}
+		if err != nil && !os.IsNotExist(err) {
+			return false
+		}
+		time.Sleep(time.Second)
+	}
+	return false
+}
+
+// make a directory like /var/lib/kubelet/plugins/kubernetes.io/pod/rbd/pool-image-image
+func makePDNameInternal(host volume.VolumeHost, pool string, image string) string {
+	return path.Join(host.GetPluginDir(RBDPluginName), "rbd", pool+"-image-"+image)
+}
+
+type RBDUtil struct{}
+
+func (util *RBDUtil) MakeGlobalPDName(rbd rbd) string {
+	return makePDNameInternal(rbd.plugin.host, rbd.pool, rbd.image)
+}
+
+func (util *RBDUtil) AttachDisk(rbd rbd) error {
+	var err error
+	devicePath := strings.Join([]string{"/dev/rbd", rbd.pool, rbd.image}, "/")
+	exist := waitForPathToExist(devicePath, 1)
+	if !exist {
+		// modprobe
+		_, err = rbd.plugin.execCommand("modprobe", []string{"rbd"})
+		if err != nil {
+			return fmt.Errorf("rbd: failed to modprobe rbd error:%v", err)
+		}
+		// rbd map
+		l := len(rbd.mon)
+		// avoid mount storm, pick a host randomly
+		start := rand.Int() % l
+		// iterate all hosts until mount succeeds.
+		for i := start; i < start+l; i++ {
+			mon := rbd.mon[i%l]
+			glog.V(1).Infof("rbd: map mon %s", mon)
+			if rbd.secret != "" {
+				_, err = rbd.plugin.execCommand("rbd",
+					[]string{"map", rbd.image, "--pool", rbd.pool, "--id", rbd.id, "-m", mon, "--key=" + rbd.secret})
+			} else {
+				_, err = rbd.plugin.execCommand("rbd",
+					[]string{"map", rbd.image, "--pool", rbd.pool, "--id", rbd.id, "-m", mon, "-k", rbd.keyring})
+			}
+			if err == nil {
+				break
+			}
+		}
+	}
+	if err != nil {
+		return err
+	}
+	exist = waitForPathToExist(devicePath, 10)
+	if !exist {
+		return errors.New("Could not map image: Timeout after 10s")
+	}
+	// mount it
+	globalPDPath := rbd.manager.MakeGlobalPDName(rbd)
+	mountpoint, err := rbd.mounter.IsMountPoint(globalPDPath)
+	if err != nil {
+		return fmt.Errorf("rbd: %s failed to check mountpoint", globalPDPath)
+	}
+	if mountpoint {
+		return nil
+	}
+
+	if err := os.MkdirAll(globalPDPath, 0750); err != nil {
+		return fmt.Errorf("rbd: failed to mkdir %s, error", globalPDPath)
+	}
+
+	if err = rbd.mounter.Mount(devicePath, globalPDPath, rbd.fsType, nil); err != nil {
+		err = fmt.Errorf("rbd: failed to mount rbd volume %s [%s] to %s, error %v", devicePath, rbd.fsType, globalPDPath, err)
+	}
+
+	return err
+}
+
+func (util *RBDUtil) DetachDisk(rbd rbd, mntPath string) error {
+	device, cnt, err := mount.GetDeviceNameFromMount(rbd.mounter, mntPath)
+	if err != nil {
+		return fmt.Errorf("rbd detach disk: failed to get device from mnt: %s\nError: %v", mntPath, err)
+	}
+	if err = rbd.mounter.Unmount(mntPath); err != nil {
+		return fmt.Errorf("rbd detach disk: failed to umount: %s\nError: %v", mntPath, err)
+	}
+	// if device is no longer used, see if can unmap
+	if cnt <= 1 {
+		// rbd unmap
+		_, err = rbd.plugin.execCommand("rbd", []string{"unmap", device})
+		if err != nil {
+			return fmt.Errorf("rbd: failed to unmap device %s:Error: %v", device, err)
+		}
+		glog.Infof("rbd: successfully unmap device %s", device)
+	}
+	return nil
+}