This is an update that allows the iscsi volume to check if a iscsi device belongs to a mpio device

If it does belong to the device then we make sure we mount the mpio device instead of
the raw device.

Heuristics
Login into /dev/disk/by-path/iqn-example.com.2999 -> /dev/sde
Check if sde existsin in /sys/block/[dm-X]/slaves/xx
If it does mount /dev/[dm-x] which will look like /dev/mapper/mpiodevicename in mount

examples/iscsi has more details

examples/iscsi/README.md

@@ -32,48 +32,45 @@ Documentation for other releases can be found at
 
 <!-- END MUNGE: UNVERSIONED_WARNING -->
 
-## Step 1. Setting up iSCSI target and iSCSI initiator
+## Introduction
 
-**Setup A.** On Fedora 21 nodes
+The Kubernetes iSCSI implementation can connect to iSCSI devices via open-iscsi and multipathd on Linux.
+Currently supported features are
+  * Connecting to one portal
+  * Mounting a device directly or via multipathd
+  * Formatting and partitioning any new device connected
 
-If you use Fedora 21 on Kubernetes node, then first install iSCSI initiator on the node:
+## Prerequisites
 
-    # yum -y install iscsi-initiator-utils
+This example expects there to be a working iSCSI target to connect to.
+If there isn't one in place then it is possible to setup a software version on Linux by following these guides
 
-then edit */etc/iscsi/iscsid.conf* to match your iSCSI target configuration.
+  * [Setup a iSCSI target on Fedora](http://www.server-world.info/en/note?os=Fedora_21&p=iscsi)
+  * [Install the iSCSI initiator on Fedora](http://www.server-world.info/en/note?os=Fedora_21&p=iscsi&f=2)
+  * [Install multipathd for mpio support if required](http://www.linuxstories.eu/2014/07/how-to-setup-dm-multipath-on-rhel.html)
 
-I mostly followed these [instructions](http://www.server-world.info/en/note?os=Fedora_21&p=iscsi) to setup iSCSI target. and these [instructions](http://www.server-world.info/en/note?os=Fedora_21&p=iscsi&f=2) to setup iSCSI initiator.
 
-**Setup B.** On Unbuntu 12.04 and Debian 7 nodes on Google Compute Engine (GCE)
+## Creating the pod with iSCSI persistent storage
 
-GCE does not provide preconfigured Fedora 21 image, so I set up the iSCSI target on a preconfigured Ubuntu 12.04 image, mostly following these [instructions](http://www.server-world.info/en/note?os=Ubuntu_12.04&p=iscsi). My Kubernetes cluster on GCE was running Debian 7 images, so I followed these [instructions](http://www.server-world.info/en/note?os=Debian_7.0&p=iscsi&f=2) to set up the iSCSI initiator.
+Once you have configured the iSCSI initiator, you can create a pod based on the example *iscsi.yaml*. In the pod YAML, you need to provide *targetPortal* (the iSCSI target's **IP** address and *port* if not the default port 3260), target's *iqn*, *lun*, and the type of the filesystem that has been created on the lun, and *readOnly* boolean. No initiator information is required.
 
-## Step 2. Creating the pod with iSCSI persistent storage
+If you want to use an iSCSI offload card or other open-iscsi transports besides tcp, setup an iSCSI interface and provide *iscsiInterface* in the pod YAML. The default name for an iscsi iface (open-iscsi parameter iface.iscsi\_ifacename) is in the format transport\_name.hwaddress when generated by iscsiadm. See [open-iscsi](http://www.open-iscsi.org/docs/README) or [openstack](http://docs.openstack.org/kilo/config-reference/content/iscsi-iface-config.html) for detailed configuration information.
-
-Once you have installed iSCSI initiator and new Kubernetes, you can create a pod based on the example *iscsi.json*. In the pod JSON, you need to provide *targetPortal* (the iSCSI target's **IP** address and *port* if not the default port 3260), target's *iqn*, *lun*, and the type of the filesystem that has been created on the lun, and *readOnly* boolean. No initiator information is required.
-
-If you want to use an iSCSI offload card or other open-iscsi transports besides tcp, setup an iSCSI interface and provide *iscsiInterface* in the pod JSON. The default name for an iscsi iface (open-iscsi parameter iface.iscsi\_ifacename) is in the format transport\_name.hwaddress when generated by iscsiadm. See [open-iscsi](http://www.open-iscsi.org/docs/README) or [openstack](http://docs.openstack.org/kilo/config-reference/content/iscsi-iface-config.html) for detailed configuration information.
 
 **Note:** If you have followed the instructions in the links above you
 may have partitioned the device, the iSCSI volume plugin does not
-currently support partitions so format the device as one partition.
+currently support partitions so format the device as one partition or leave the device raw and Kubernetes will partition and format it one first mount.
-Make sure you have the correct device name then run the following as
+
-root to format it:
+
+Once the pod config is created, run it on the Kubernetes master:
 
 ```console
-mkfs.ext4 /dev/<name of device>
+kubectl create -f ./your_new_pod.yaml
 ```
 
-Once your pod is created, run it on the Kubernetes master:
+Here is the example pod created and expected output:
 
 ```console
-kubectl create -f ./your_new_pod.json
+# kubectl create -f examples/iscsi/iscsi.yaml
-```
-
-Here is my command and output:
-
-```console
-# kubectl create -f examples/iscsi/iscsi.json
 # kubectl get pods
 NAME      READY     STATUS    RESTARTS   AGE
 iscsipd   2/2       RUNNING   0           2m
@@ -81,6 +78,8 @@ iscsipd   2/2       RUNNING   0           2m
 
 On the Kubernetes node, verify the mount output
 
+For a non mpio device the output should look like the following
+
 ```console
 # mount |grep kub
 /dev/sdb on /var/lib/kubelet/plugins/kubernetes.io/iscsi/10.0.2.15:3260-iqn.2001-04.com.example:storage.kube.sys1.xyz-lun-0 type ext4 (ro,relatime,data=ordered)
@@ -89,6 +88,17 @@ On the Kubernetes node, verify the mount output
 /dev/sdc on /var/lib/kubelet/pods/f527ca5b-6d87-11e5-aa7e-080027ff6387/volumes/kubernetes.io~iscsi/iscsipd-rw type ext4 (rw,relatime,data=ordered)
 ```
 
+And for a node with mpio enabled the expected output would be similar to the following
+
+```console
+# mount |grep kub
+/dev/mapper/mpatha on /var/lib/kubelet/plugins/kubernetes.io/iscsi/10.0.2.15:3260-iqn.2001-04.com.example:storage.kube.sys1.xyz-lun-0 type ext4 (ro,relatime,data=ordered)
+/dev/mapper/mpatha on /var/lib/kubelet/pods/f527ca5b-6d87-11e5-aa7e-080027ff6387/volumes/kubernetes.io~iscsi/iscsipd-ro type ext4 (ro,relatime,data=ordered)
+/dev/mapper/mpathb on /var/lib/kubelet/plugins/kubernetes.io/iscsi/10.0.2.15:3260-iqn.2001-04.com.example:storage.kube.sys1.xyz-lun-1 type ext4 (rw,relatime,data=ordered)
+/dev/mapper/mpathb on /var/lib/kubelet/pods/f527ca5b-6d87-11e5-aa7e-080027ff6387/volumes/kubernetes.io~iscsi/iscsipd-rw type ext4 (rw,relatime,data=ordered)
+```
+
+
 If you ssh to that machine, you can run `docker ps` to see the actual pod.
 
 ```console

examples/iscsi/iscsi.json

@@ -1,53 +0,0 @@
-{
-    "apiVersion": "v1",
-    "kind": "Pod",
-    "metadata": {
-        "name": "iscsipd"
-    },
-    "spec": {
-        "containers": [
-            {
-                "name": "iscsipd-ro",
-                "image": "kubernetes/pause",
-                "volumeMounts": [
-                    {
-                        "mountPath": "/mnt/iscsipd",
-                        "name": "iscsipd-ro"
-                    }
-                ]
-            },
-            {
-                "name": "iscsipd-rw",
-                "image": "kubernetes/pause",
-                "volumeMounts": [
-                    {
-                        "mountPath": "/mnt/iscsipd",
-                        "name": "iscsipd-rw"
-                    }
-                ]
-            }
-        ],
-        "volumes": [
-            {
-                "name": "iscsipd-ro",
-                "iscsi": {
-                    "targetPortal": "10.0.2.15:3260",
-                    "iqn": "iqn.2001-04.com.example:storage.kube.sys1.xyz",
-                    "lun": 0,
-                    "fsType": "ext4",
-                    "readOnly": true
-                }
-            },
-            {
-                "name": "iscsipd-rw",
-                "iscsi": {
-                    "targetPortal": "10.0.2.15:3260",
-                    "iqn": "iqn.2001-04.com.example:storage.kube.sys1.xyz",
-                    "lun": 1,
-                    "fsType": "ext4",
-                    "readOnly": false
-                }
-            }
-        ]
-    }
-}

examples/iscsi/iscsi.yaml

@@ -0,0 +1,32 @@
+---
+apiVersion: v1
+kind: Pod
+metadata:
+  name: iscsipd
+spec:
+  containers:
+  - name: iscsipd-ro
+    image: kubernetes/pause
+    volumeMounts:
+    - mountPath: "/mnt/iscsipd"
+      name: iscsipd-ro
+  - name: iscsipd-rw
+    image: kubernetes/pause
+    volumeMounts:
+    - mountPath: "/mnt/iscsipd"
+      name: iscsipd-rw
+  volumes:
+  - name: iscsipd-ro
+    iscsi:
+      targetPortal: 10.0.2.15:3260
+      iqn: iqn.2001-04.com.example:storage.kube.sys1.xyz
+      lun: 0
+      fsType: ext4
+      readOnly: true
+  - name: iscsipd-rw
+    iscsi:
+      targetPortal: 10.0.2.15:3260
+      iqn: iqn.2001-04.com.example:storage.kube.sys1.xyz
+      lun: 1
+      fsType: ext4
+      readOnly: false

pkg/volume/fc/fc_util.go

@@ -51,6 +51,8 @@ func (handler *osIOHandler) WriteFile(filename string, data []byte, perm os.File
 }
 
 // given a disk path like /dev/sdx, find the devicemapper parent
+// TODO #23192 Convert this code to use the generic code in ../util
+// which is used by the iSCSI implementation
 func findMultipathDeviceMapper(disk string, io ioHandler) string {
 	sys_path := "/sys/block/"
 	if dirs, err := io.ReadDir(sys_path); err == nil {

pkg/volume/iscsi/iscsi.go

@@ -27,6 +27,7 @@ import (
 	"k8s.io/kubernetes/pkg/util/mount"
 	utilstrings "k8s.io/kubernetes/pkg/util/strings"
 	"k8s.io/kubernetes/pkg/volume"
+	ioutil "k8s.io/kubernetes/pkg/volume/util"
 )
 
 // This is the primary entrypoint for volume plugins.
@@ -106,6 +107,7 @@ func (plugin *iscsiPlugin) newMounterInternal(spec *volume.Spec, podUID types.UI
 		fsType:     iscsi.FSType,
 		readOnly:   readOnly,
 		mounter:    &mount.SafeFormatAndMount{Interface: mounter, Runner: exec.New()},
+		deviceUtil: ioutil.NewDeviceHandler(ioutil.NewIOHandler()),
 	}, nil
 }
 
@@ -155,6 +157,7 @@ type iscsiDiskMounter struct {
 	readOnly   bool
 	fsType     string
 	mounter    *mount.SafeFormatAndMount
+	deviceUtil ioutil.DeviceUtil
 }
 
 var _ volume.Mounter = &iscsiDiskMounter{}

pkg/volume/iscsi/iscsi_util.go

@@ -136,6 +136,10 @@ func (util *ISCSIUtil) AttachDisk(b iscsiDiskMounter) error {
 		return err
 	}
 
+	// check if the dev is using mpio and if so mount it via the dm-XX device
+	if mappedDevicePath := b.deviceUtil.FindMultipathDeviceForDevice(devicePath); mappedDevicePath != "" {
+		devicePath = mappedDevicePath
+	}
 	err = b.mounter.FormatAndMount(devicePath, globalPDPath, b.fsType, nil)
 	if err != nil {
 		glog.Errorf("iscsi: failed to mount iscsi volume %s [%s] to %s, error %v", devicePath, b.fsType, globalPDPath, err)

pkg/volume/util/device_util.go

@@ -0,0 +1,31 @@
+/*
+Copyright 2016 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 util
+
+//DeviceUtil is a util for common device methods
+type DeviceUtil interface {
+	FindMultipathDeviceForDevice(disk string) string
+}
+
+type deviceHandler struct {
+	get_io IoUtil
+}
+
+//NewDeviceHandler Create a new IoHandler implementation
+func NewDeviceHandler(io IoUtil) DeviceUtil {
+	return &deviceHandler{get_io: io}
+}

pkg/volume/util/device_util_linux.go

@@ -0,0 +1,61 @@
+// +build linux
+
+/*
+Copyright 2016 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 util
+
+import (
+	"errors"
+	"strings"
+)
+
+// FindMultipathDeviceForDevice given a device name like /dev/sdx, find the devicemapper parent
+func (handler *deviceHandler) FindMultipathDeviceForDevice(device string) string {
+	io := handler.get_io
+	disk, err := findDeviceForPath(device, io)
+	if err != nil {
+		return ""
+	}
+	sysPath := "/sys/block/"
+	if dirs, err := io.ReadDir(sysPath); err == nil {
+		for _, f := range dirs {
+			name := f.Name()
+			if strings.HasPrefix(name, "dm-") {
+				if _, err1 := io.Lstat(sysPath + name + "/slaves/" + disk); err1 == nil {
+					return "/dev/" + name
+				}
+			}
+		}
+	}
+	return ""
+}
+
+// findDeviceForPath Find the underlaying disk for a linked path such as /dev/disk/by-path/XXXX or /dev/mapper/XXXX
+// will return sdX or hdX etc, if /dev/sdX is passed in then sdX will be returned
+func findDeviceForPath(path string, io IoUtil) (string, error) {
+	devicePath, err := io.EvalSymlinks(path)
+	if err != nil {
+		return "", err
+	}
+	// if path /dev/hdX split into "", "dev", "hdX" then we will
+	// return just the last part
+	parts := strings.Split(devicePath, "/")
+	if len(parts) == 3 && strings.HasPrefix(parts[1], "dev") {
+		return parts[2], nil
+	}
+	return "", errors.New("Illegal path for device " + devicePath)
+}

pkg/volume/util/device_util_linux_test.go

@@ -0,0 +1,136 @@
+// +build linux
+
+/*
+Copyright 2016 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 util
+
+import (
+	"errors"
+	"os"
+	"testing"
+	"time"
+)
+
+type mockOsIOHandler struct{}
+
+func (handler *mockOsIOHandler) ReadDir(dirname string) ([]os.FileInfo, error) {
+	switch dirname {
+	case "/sys/block/dm-2/slaves/":
+		f := &fakeFileInfo{
+			name: "sda",
+		}
+		return []os.FileInfo{f}, nil
+	case "/sys/block/":
+		f1 := &fakeFileInfo{
+			name: "sda",
+		}
+		f2 := &fakeFileInfo{
+			name: "dm-1",
+		}
+		return []os.FileInfo{f1, f2}, nil
+	}
+	return nil, nil
+}
+
+func (handler *mockOsIOHandler) Lstat(name string) (os.FileInfo, error) {
+	links := map[string]string{
+		"/sys/block/dm-1/slaves/sda": "sda",
+		"/dev/sda":                   "sda",
+	}
+	if dev, ok := links[name]; ok {
+		return &fakeFileInfo{name: dev}, nil
+	}
+	return nil, errors.New("Not Implemented for Mock")
+}
+
+func (handler *mockOsIOHandler) EvalSymlinks(path string) (string, error) {
+	links := map[string]string{
+		"/returns/a/dev":                                              "/dev/sde",
+		"/returns/non/dev":                                            "/sys/block",
+		"/dev/disk/by-path/127.0.0.1:3260-eui.02004567A425678D-lun-0": "/dev/sda",
+		"/dev/dm-2": "/dev/dm-2",
+		"/dev/dm-3": "/dev/dm-3",
+		"/dev/sde":  "/dev/sde",
+	}
+	return links[path], nil
+}
+
+func (handler *mockOsIOHandler) WriteFile(filename string, data []byte, perm os.FileMode) error {
+	return errors.New("Not Implemented for Mock")
+}
+
+type fakeFileInfo struct {
+	name string
+}
+
+func (fi *fakeFileInfo) Name() string {
+	return fi.name
+}
+
+func (fi *fakeFileInfo) Size() int64 {
+	return 0
+}
+
+func (fi *fakeFileInfo) Mode() os.FileMode {
+	return 777
+}
+
+func (fi *fakeFileInfo) ModTime() time.Time {
+	return time.Now()
+}
+func (fi *fakeFileInfo) IsDir() bool {
+	return false
+}
+
+func (fi *fakeFileInfo) Sys() interface{} {
+	return nil
+}
+
+func TestFindMultipathDeviceForDevice(t *testing.T) {
+	mockDeviceUtil := NewDeviceHandler(&mockOsIOHandler{})
+	dev := mockDeviceUtil.FindMultipathDeviceForDevice("/dev/disk/by-path/127.0.0.1:3260-eui.02004567A425678D-lun-0")
+	if dev != "/dev/dm-1" {
+		t.Fatalf("mpio device not found dm-1 expected got [%s]", dev)
+	}
+	dev = mockDeviceUtil.FindMultipathDeviceForDevice("/dev/disk/by-path/empty")
+	if dev != "" {
+		t.Fatalf("mpio device not found '' expected got [%s]", dev)
+	}
+}
+
+func TestfindDeviceForPath(t *testing.T) {
+	io := &mockOsIOHandler{}
+
+	disk, err := findDeviceForPath("/dev/sde", io)
+	if disk != "sde" {
+		t.Fatalf("disk [%s] didn't match expected sde", disk)
+	}
+	disk, err = findDeviceForPath("/returns/a/dev", io)
+	if disk != "sde" {
+		t.Fatalf("disk [%s] didn't match expected sde", disk)
+	}
+	_, err = findDeviceForPath("/returns/non/dev", io)
+	if err == nil {
+		t.Fatalf("link is to incorrect dev")
+	}
+
+	_, err = findDeviceForPath("/path/doesnt/exist", &osIOHandler{})
+	if err == nil {
+		t.Fatalf("path shouldn't exist but still doesn't give an error")
+	}
+
+}

pkg/volume/util/device_util_unsupported.go

@@ -0,0 +1,24 @@
+// +build !linux
+
+/*
+Copyright 2016 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 util
+
+// FindMultipathDeviceForDevice unsupported returns ""
+func (handler *deviceHandler) FindMultipathDeviceForDevice(device string) string {
+	return ""
+}

pkg/volume/util/io_util.go

@@ -0,0 +1,48 @@
+/*
+Copyright 2016 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 util
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+)
+
+//IoUtil is a util for common IO operations
+//it also backports certain operations from golang 1.5
+type IoUtil interface {
+	ReadDir(dirname string) ([]os.FileInfo, error)
+	Lstat(name string) (os.FileInfo, error)
+	EvalSymlinks(path string) (string, error)
+}
+
+type osIOHandler struct{}
+
+//NewIOHandler Create a new IoHandler implementation
+func NewIOHandler() IoUtil {
+	return &osIOHandler{}
+}
+
+func (handler *osIOHandler) ReadDir(dirname string) ([]os.FileInfo, error) {
+	return ioutil.ReadDir(dirname)
+}
+func (handler *osIOHandler) Lstat(name string) (os.FileInfo, error) {
+	return os.Lstat(name)
+}
+func (handler *osIOHandler) EvalSymlinks(path string) (string, error) {
+	return filepath.EvalSymlinks(path)
+}