Feature: Multi-Attach for io2 block devices

Signed-off-by: Eddie Torres <[email protected]>
kubernetes-sigs · Oct 25, 2023 · 5918d0b · 5918d0b
1 parent fdb9866
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diff --git a/docs/multi-attach.md b/docs/multi-attach.md
@@ -0,0 +1,81 @@
+# Multi-Attach
+
+The multi-attach capability allows you to attach a single EBS volume to multiple EC2 instances located within the same Availability Zone (AZ). This shared volume can be utilized by several pods running on distinct nodes.
+
+## Important
+
+- EBS Multi-Attach does not support standard file systems. Standard file systems such as `XFS`, `EXT3`, `EXT4`, and `NTFS` aren't designed to be simultaneously accessed by multiple servers or EC2 instances.
+- Simultaneous access to a standard file system can result in data corruption or data loss.
+- You should use a clustered file system to ensure data resiliency and reliability for your production workloads.
+- Multi-Attach is only enabled for `IO2` block devices.
+
+Refer to the official AWS documentation on [Multi-Attach](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ebs-volumes-multi.html) for more information, best practices, and limitations of this capability.
+
+## Example
+
+1. Create a `StorageClass` referencing an `IO2` volume type:
+```
+apiVersion: storage.k8s.io/v1
+kind: StorageClass
+metadata:
+  name: ebs-sc
+provisioner: ebs.csi.aws.com
+volumeBindingMode: WaitForFirstConsumer
+parameters:
+  type: io2
+  iops: "1000"
+```
+
+2. Create a `PersistentVolumeClaim` referencing the `ReadWriteMany` access and `Block` device modes:
+```
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: block-claim
+spec:
+  accessModes:
+    - ReadWriteMany
+  volumeMode: Block
+  storageClassName: ebs-sc
+  resources:
+    requests:
+      storage: 4Gi
+```
+
+3. Create a `DaemonSet` to deploy the driver on all nodes:
+```
+apiVersion: apps/v1
+kind: DaemonSet
+metadata:
+  name: app-daemon
+spec:
+  selector:
+    matchLabels:
+      name: app
+  template:
+    metadata:
+      labels:
+        name: app
+    spec:
+      containers:
+      - name: app
+        image: busybox
+        command: ["/bin/sh", "-c"]
+        args: ["tail -f /dev/null"]
+        volumeDevices:
+        - name: data
+          devicePath: /dev/xvda
+      volumes:
+      - name: data
+        persistentVolumeClaim:
+          claimName: block-claim
+```
+
+4. Verify the `DaemonSet` is running:
+```
+$ kubectl get pods -A
+
+NAMESPACE     NAME                                   READY   STATUS    RESTARTS       AGE
+default       app-daemon-9hdgw                       1/1     Running   0              18s
+default       app-daemon-xm8zr                       1/1     Running   0              18s
+```
diff --git a/pkg/cloud/cloud.go b/pkg/cloud/cloud.go
@@ -197,8 +197,9 @@ type DiskOptions struct {
 	BlockExpress           bool
 	// KmsKeyID represents a fully qualified resource name to the key to use for encryption.
 	// example: arn:aws:kms:us-east-1:012345678910:key/abcd1234-a123-456a-a12b-a123b4cd56ef
-	KmsKeyID   string
-	SnapshotID string
+	KmsKeyID           string
+	SnapshotID         string
+	MultiAttachEnabled bool
 }
 
 // ModifyDiskOptions represents parameters to modify an EBS volume
@@ -345,6 +346,10 @@ func (c *cloud) CreateDisk(ctx context.Context, volumeName string, diskOptions *
 		return nil, fmt.Errorf("invalid AWS VolumeType %q", diskOptions.VolumeType)
 	}
 
+	if diskOptions.MultiAttachEnabled && createType != VolumeTypeIO2 {
+		return nil, fmt.Errorf("CreateDisk: multi-attach is only supported for io2 volumes")
+	}
+
 	if maxIops > 0 {
 		if diskOptions.IOPS > 0 {
 			requestedIops = int64(diskOptions.IOPS)
@@ -381,11 +386,12 @@ func (c *cloud) CreateDisk(ctx context.Context, volumeName string, diskOptions *
 	clientToken := sha256.Sum256([]byte(volumeName))
 
 	requestInput := &ec2.CreateVolumeInput{
-		AvailabilityZone: aws.String(zone),
-		ClientToken:      aws.String(hex.EncodeToString(clientToken[:])),
-		Size:             aws.Int64(capacityGiB),
-		VolumeType:       aws.String(createType),
-		Encrypted:        aws.Bool(diskOptions.Encrypted),
+		AvailabilityZone:   aws.String(zone),
+		ClientToken:        aws.String(hex.EncodeToString(clientToken[:])),
+		Size:               aws.Int64(capacityGiB),
+		VolumeType:         aws.String(createType),
+		Encrypted:          aws.Bool(diskOptions.Encrypted),
+		MultiAttachEnabled: aws.Bool(diskOptions.MultiAttachEnabled),
 	}
 
 	if !util.IsSBE(zone) {
@@ -549,40 +555,19 @@ func (c *cloud) AttachDisk(ctx context.Context, volumeID, nodeID string) (string
 
 		resp, attachErr := c.ec2.AttachVolumeWithContext(ctx, request)
 		if attachErr != nil {
-			var awsErr awserr.Error
-			if errors.As(attachErr, &awsErr) {
-				if awsErr.Code() == "VolumeInUse" {
-					return "", ErrVolumeInUse
-				}
-			}
 			return "", fmt.Errorf("could not attach volume %q to node %q: %w", volumeID, nodeID, attachErr)
 		}
 		klog.V(5).InfoS("[Debug] AttachVolume", "volumeID", volumeID, "nodeID", nodeID, "resp", resp)
 	}
 
-	attachment, err := c.WaitForAttachmentState(ctx, volumeID, volumeAttachedState, *instance.InstanceId, device.Path, device.IsAlreadyAssigned)
+	_, err = c.WaitForAttachmentState(ctx, volumeID, volumeAttachedState, *instance.InstanceId, device.Path, device.IsAlreadyAssigned)
 
 	// This is the only situation where we taint the device
 	if err != nil {
 		device.Taint()
 		return "", err
 	}
 
-	// Double check the attachment to be 100% sure we attached the correct volume at the correct mountpoint
-	// It could happen otherwise that we see the volume attached from a previous/separate AttachVolume call,
-	// which could theoretically be against a different device (or even instance).
-	if attachment == nil {
-		// Impossible?
-		return "", fmt.Errorf("unexpected state: attachment nil after attached %q to %q", volumeID, nodeID)
-	}
-	if device.Path != aws.StringValue(attachment.Device) {
-		// Already checked in waitForAttachmentState(), but just to be sure...
-		return "", fmt.Errorf("disk attachment of %q to %q failed: requested device %q but found %q", volumeID, nodeID, device.Path, aws.StringValue(attachment.Device))
-	}
-	if *instance.InstanceId != aws.StringValue(attachment.InstanceId) {
-		return "", fmt.Errorf("disk attachment of %q to %q failed: requested instance %q but found %q", volumeID, nodeID, *instance.InstanceId, aws.StringValue(attachment.InstanceId))
-	}
-
 	// TODO: Check volume capability matches for ALREADY_EXISTS
 	// This could happen when request volume already attached to request node,
 	// but is incompatible with the specified volume_capability or readonly flag
@@ -674,41 +659,12 @@ func (c *cloud) WaitForAttachmentState(ctx context.Context, volumeID, expectedSt
 			return false, nil
 		}
 
-		if len(volume.Attachments) > 1 {
-			// Shouldn't happen; log so we know if it is
-			klog.InfoS("Found multiple attachments for volume", "volumeID", volumeID, "volume", volume)
-		}
-		attachmentState := ""
+		attachmentState := volumeDetachedState
+
 		for _, a := range volume.Attachments {
-			if attachmentState != "" {
-				// Shouldn't happen; log so we know if it is
-				klog.InfoS("Found multiple attachments for volume", "volumeID", volumeID, "volume", volume)
-			}
-			if a.State != nil {
+			if a.State != nil && aws.StringValue(a.InstanceId) == expectedInstance && aws.StringValue(a.Device) == expectedDevice {
+				attachmentState = aws.StringValue(a.State)
 				attachment = a
-				attachmentState = *a.State
-			} else {
-				// Shouldn't happen; log so we know if it is
-				klog.InfoS("Ignoring nil attachment state for volume", "volumeID", volumeID, "attachment", a)
-			}
-		}
-		if attachmentState == "" {
-			attachmentState = volumeDetachedState
-		}
-		if attachment != nil {
-			// AWS eventual consistency can go back in time.
-			// For example, we're waiting for a volume to be attached as /dev/xvdba, but AWS can tell us it's
-			// attached as /dev/xvdbb, where it was attached before and it was already detached.
-			// Retry couple of times, hoping AWS starts reporting the right status.
-			device := aws.StringValue(attachment.Device)
-			if expectedDevice != "" && device != "" && device != expectedDevice {
-				klog.InfoS("Expected device for volume not found", "expectedDevice", expectedDevice, "expectedState", expectedState, "volumeID", volumeID, "device", device, "attachmentState", attachmentState)
-				return false, nil
-			}
-			instanceID := aws.StringValue(attachment.InstanceId)
-			if expectedInstance != "" && instanceID != "" && instanceID != expectedInstance {
-				klog.InfoS("Expected instance for volume not found", "expectedInstance", expectedInstance, "expectedState", expectedState, "volumeID", volumeID, "instanceID", instanceID, "attachmentState", attachmentState)
-				return false, nil
 			}
 		}
 

diff --git a/pkg/cloud/cloud_test.go b/pkg/cloud/cloud_test.go
@@ -575,6 +575,43 @@ func TestCreateDisk(t *testing.T) {
 			},
 			expErr: nil,
 		},
+		{
+			name:       "success: multi-attach with IO2",
+			volumeName: "vol-test-name",
+			diskOptions: &DiskOptions{
+				CapacityBytes:      util.GiBToBytes(4),
+				Tags:               map[string]string{VolumeNameTagKey: "vol-test", AwsEbsDriverTagKey: "true"},
+				VolumeType:         VolumeTypeIO2,
+				MultiAttachEnabled: true,
+				IOPSPerGB:          10000,
+			},
+			expDisk: &Disk{
+				VolumeID:         "vol-test",
+				CapacityGiB:      4,
+				AvailabilityZone: defaultZone,
+			},
+			expCreateVolumeInput: &ec2.CreateVolumeInput{
+				Iops: aws.Int64(2000),
+			},
+			expErr: nil,
+		},
+		{
+			name:       "failure: multi-attach with GP3",
+			volumeName: "vol-test-name",
+			diskOptions: &DiskOptions{
+				CapacityBytes:      util.GiBToBytes(4),
+				Tags:               map[string]string{VolumeNameTagKey: "vol-test", AwsEbsDriverTagKey: "true"},
+				VolumeType:         VolumeTypeGP3,
+				MultiAttachEnabled: true,
+				IOPSPerGB:          10000,
+			},
+			expDisk: &Disk{
+				VolumeID:         "vol-test",
+				CapacityGiB:      4,
+				AvailabilityZone: defaultZone,
+			},
+			expErr: fmt.Errorf("CreateDisk: multi-attach is only supported for io2 volumes"),
+		},
 	}
 
 	for _, tc := range testCases {
@@ -715,17 +752,18 @@ func TestAttachDisk(t *testing.T) {
 		name     string
 		volumeID string
 		nodeID   string
+		nodeID2  string
 		path     string
 		expErr   error
-		mockFunc func(*MockEC2API, context.Context, string, string, string, dm.DeviceManager)
+		mockFunc func(*MockEC2API, context.Context, string, string, string, string, dm.DeviceManager)
 	}{
 		{
 			name:     "success: AttachVolume normal",
 			volumeID: defaultVolumeID,
 			nodeID:   defaultNodeID,
 			path:     defaultPath,
 			expErr:   nil,
-			mockFunc: func(mockEC2 *MockEC2API, ctx context.Context, volumeID, nodeID, path string, dm dm.DeviceManager) {
+			mockFunc: func(mockEC2 *MockEC2API, ctx context.Context, volumeID, nodeID, nodeID2, path string, dm dm.DeviceManager) {
 				volumeRequest := createVolumeRequest(volumeID)
 				instanceRequest := createInstanceRequest(nodeID)
 				attachRequest := createAttachRequest(volumeID, nodeID, path)
@@ -743,7 +781,7 @@ func TestAttachDisk(t *testing.T) {
 			nodeID:   defaultNodeID,
 			path:     defaultPath,
 			expErr:   nil,
-			mockFunc: func(mockEC2 *MockEC2API, ctx context.Context, volumeID, nodeID, path string, dm dm.DeviceManager) {
+			mockFunc: func(mockEC2 *MockEC2API, ctx context.Context, volumeID, nodeID, nodeID2, path string, dm dm.DeviceManager) {
 				volumeRequest := createVolumeRequest(volumeID)
 				instanceRequest := createInstanceRequest(nodeID)
 
@@ -762,7 +800,7 @@ func TestAttachDisk(t *testing.T) {
 			nodeID:   defaultNodeID,
 			path:     defaultPath,
 			expErr:   fmt.Errorf("could not attach volume %q to node %q: %w", defaultVolumeID, defaultNodeID, errors.New("AttachVolume error")),
-			mockFunc: func(mockEC2 *MockEC2API, ctx context.Context, volumeID, nodeID, path string, dm dm.DeviceManager) {
+			mockFunc: func(mockEC2 *MockEC2API, ctx context.Context, volumeID, nodeID, nodeID2, path string, dm dm.DeviceManager) {
 				instanceRequest := createInstanceRequest(nodeID)
 				attachRequest := createAttachRequest(volumeID, nodeID, path)
 
@@ -778,7 +816,7 @@ func TestAttachDisk(t *testing.T) {
 			nodeID:   defaultNodeID,
 			path:     defaultPath,
 			expErr:   fmt.Errorf("could not attach volume %q to node %q: %w", defaultVolumeID, defaultNodeID, ErrVolumeInUse),
-			mockFunc: func(mockEC2 *MockEC2API, ctx context.Context, volumeID, nodeID, path string, dm dm.DeviceManager) {
+			mockFunc: func(mockEC2 *MockEC2API, ctx context.Context, volumeID, nodeID, nodeID2, path string, dm dm.DeviceManager) {
 				instanceRequest := createInstanceRequest(nodeID)
 				attachRequest := createAttachRequest(volumeID, nodeID, path)
 
@@ -788,6 +826,52 @@ func TestAttachDisk(t *testing.T) {
 				)
 			},
 		},
+		{
+			name:     "success: AttachVolume multi-attach",
+			volumeID: defaultVolumeID,
+			nodeID:   defaultNodeID,
+			nodeID2:  "node-1239",
+			path:     defaultPath,
+			expErr:   nil,
+			mockFunc: func(mockEC2 *MockEC2API, ctx context.Context, volumeID, nodeID, nodeID2, path string, dm dm.DeviceManager) {
+				volumeRequest := createVolumeRequest(volumeID)
+				instanceRequest := createInstanceRequest(nodeID)
+				attachRequest := createAttachRequest(volumeID, nodeID, path)
+
+				createInstanceRequest2 := createInstanceRequest(nodeID2)
+				attachRequest2 := createAttachRequest(volumeID, nodeID2, path)
+
+				dvOutput := &ec2.DescribeVolumesOutput{
+					Volumes: []*ec2.Volume{
+						{
+							VolumeId: aws.String(volumeID),
+							Attachments: []*ec2.VolumeAttachment{
+								{
+									Device:     aws.String(path),
+									InstanceId: aws.String(nodeID),
+									State:      aws.String("attached"),
+								},
+								{
+									Device:     aws.String(path),
+									InstanceId: aws.String(nodeID2),
+									State:      aws.String("attached"),
+								},
+							},
+						},
+					},
+				}
+
+				gomock.InOrder(
+					mockEC2.EXPECT().DescribeInstancesWithContext(ctx, instanceRequest).Return(newDescribeInstancesOutput(nodeID), nil),
+					mockEC2.EXPECT().AttachVolumeWithContext(ctx, attachRequest).Return(createAttachVolumeOutput(volumeID, nodeID, path, "attached"), nil),
+					mockEC2.EXPECT().DescribeVolumesWithContext(ctx, volumeRequest).Return(createDescribeVolumesOutput(volumeID, nodeID, path, "attached"), nil),
+
+					mockEC2.EXPECT().DescribeInstancesWithContext(ctx, createInstanceRequest2).Return(newDescribeInstancesOutput(nodeID2), nil),
+					mockEC2.EXPECT().AttachVolumeWithContext(ctx, attachRequest2).Return(createAttachVolumeOutput(volumeID, nodeID2, path, "attached"), nil),
+					mockEC2.EXPECT().DescribeVolumesWithContext(ctx, volumeRequest).Return(dvOutput, nil),
+				)
+			},
+		},
 	}
 
 	for _, tc := range testCases {
@@ -799,7 +883,7 @@ func TestAttachDisk(t *testing.T) {
 			ctx := context.Background()
 			dm := c.(*cloud).dm
 
-			tc.mockFunc(mockEC2, ctx, tc.volumeID, tc.nodeID, tc.path, dm)
+			tc.mockFunc(mockEC2, ctx, tc.volumeID, tc.nodeID, tc.nodeID2, tc.path, dm)
 
 			devicePath, err := c.AttachDisk(ctx, tc.volumeID, tc.nodeID)
 
@@ -811,6 +895,12 @@ func TestAttachDisk(t *testing.T) {
 				assert.Equal(t, tc.path, devicePath)
 			}
 
+			if tc.nodeID2 != "" {
+				devicePath, err := c.AttachDisk(ctx, tc.volumeID, tc.nodeID2)
+				assert.NoError(t, err)
+				assert.Equal(t, tc.path, devicePath)
+			}
+
 			mockCtrl.Finish()
 		})
 	}