Remove block-device-mapping from attach limit

meta-data/block-device-mapping reports devices that were attached to the
VM at the time the VM was started. It does not reflect devices
attached/detached later.

In addition, even when it showed the attachments accurately, the CSI driver
uses this information only at the driver startup. At this time, there
may be some CSI volumes attached from the previous node boot. Those
volumes are then counted as permanently attached to the node, while
Kubernetes may detach them later.

Therefore do not count block-device-mapping at all and always reserve just
1 attachment for the root disk. Assume all other attachments are CSI
volumes, and let Kubernetes do the calculations of attached volumes
instead.

pkg/cloud/metadata.go

@@ -26,13 +26,12 @@ import (
 
 // Metadata is info about the ec2 instance on which the driver is running
 type Metadata struct {
-	InstanceID             string
-	InstanceType           string
-	Region                 string
-	AvailabilityZone       string
-	NumAttachedENIs        int
-	NumBlockDeviceMappings int
-	OutpostArn             arn.ARN
+	InstanceID       string
+	InstanceType     string
+	Region           string
+	AvailabilityZone string
+	NumAttachedENIs  int
+	OutpostArn       arn.ARN
 }
 
 const (
@@ -72,10 +71,6 @@ func (m *Metadata) GetNumAttachedENIs() int {
 	return m.NumAttachedENIs
 }
 
-func (m *Metadata) GetNumBlockDeviceMappings() int {
-	return m.NumBlockDeviceMappings
-}
-
 // GetOutpostArn returns outpost arn if instance is running on an outpost. empty otherwise.
 func (m *Metadata) GetOutpostArn() arn.ARN {
 	return m.OutpostArn

pkg/cloud/metadata_ec2.go

@@ -61,23 +61,13 @@ func EC2MetadataInstanceInfo(svc EC2Metadata, regionFromSession string) (*Metada
 	}
 
 	attachedENIs := strings.Count(enis, "\n") + 1
-	blockDevMappings := 0
-
-	if !util.IsSBE(doc.Region) {
-		mappings, mapErr := svc.GetMetadata(blockDevicesEndpoint)
-		if mapErr != nil {
-			return nil, fmt.Errorf("could not get number of block device mappings: %w", err)
-		}
-		blockDevMappings = strings.Count(mappings, "ebs")
-	}
 
 	instanceInfo := Metadata{
-		InstanceID:             doc.InstanceID,
-		InstanceType:           doc.InstanceType,
-		Region:                 doc.Region,
-		AvailabilityZone:       doc.AvailabilityZone,
-		NumAttachedENIs:        attachedENIs,
-		NumBlockDeviceMappings: blockDevMappings,
+		InstanceID:       doc.InstanceID,
+		InstanceType:     doc.InstanceType,
+		Region:           doc.Region,
+		AvailabilityZone: doc.AvailabilityZone,
+		NumAttachedENIs:  attachedENIs,
 	}
 
 	outpostArn, err := svc.GetMetadata(outpostArnEndpoint)

pkg/cloud/metadata_interface.go

@@ -12,7 +12,6 @@ type MetadataService interface {
 	GetRegion() string
 	GetAvailabilityZone() string
 	GetNumAttachedENIs() int
-	GetNumBlockDeviceMappings() int
 	GetOutpostArn() arn.ARN
 }
 

pkg/cloud/metadata_k8s.go

@@ -75,12 +75,11 @@ func KubernetesAPIInstanceInfo(clientset kubernetes.Interface) (*Metadata, error
 	}
 
 	instanceInfo := Metadata{
-		InstanceID:             instanceID,
-		InstanceType:           instanceType,
-		Region:                 region,
-		AvailabilityZone:       availabilityZone,
-		NumAttachedENIs:        1, // All nodes have at least 1 attached ENI, so we'll use that
-		NumBlockDeviceMappings: 0,
+		InstanceID:       instanceID,
+		InstanceType:     instanceType,
+		Region:           region,
+		AvailabilityZone: availabilityZone,
+		NumAttachedENIs:  1, // All nodes have at least 1 attached ENI, so we'll use that
 	}
 
 	return &instanceInfo, nil

pkg/cloud/metadata_test.go

@@ -60,7 +60,6 @@ func TestNewMetadataService(t *testing.T) {
 		imdsBlockDeviceOutput            string
 		imdsENIOutput                    string
 		expectedENIs                     int
-		expectedBlockDevices             int
 		expectedOutpostArn               arn.ARN
 		expectedErr                      error
 		node                             v1.Node
@@ -318,20 +317,6 @@ func TestNewMetadataService(t *testing.T) {
 			imdsENIOutput: "00:00:00:00:00:00\n00:00:00:00:00:01",
 			expectedENIs:  2,
 		},
-		{
-			name:                 "success: GetMetadata() returns correct number of block device mappings",
-			ec2metadataAvailable: true,
-			getInstanceIdentityDocumentValue: ec2metadata.EC2InstanceIdentityDocument{
-				InstanceID:       stdInstanceID,
-				InstanceType:     stdInstanceType,
-				Region:           stdRegion,
-				AvailabilityZone: stdAvailabilityZone,
-			},
-			imdsENIOutput:         "00:00:00:00:00:00",
-			expectedENIs:          1,
-			imdsBlockDeviceOutput: "ami\nroot\nebs1\nebs2",
-			expectedBlockDevices:  2,
-		},
 		{
 			name:                 "success: region from session is snow",
 			ec2metadataAvailable: true,
@@ -341,10 +326,9 @@ func TestNewMetadataService(t *testing.T) {
 				Region:           "",
 				AvailabilityZone: "",
 			},
-			imdsENIOutput:        "00:00:00:00:00:00",
-			expectedENIs:         1,
-			regionFromSession:    snowRegion,
-			expectedBlockDevices: 0,
+			imdsENIOutput:     "00:00:00:00:00:00",
+			expectedENIs:      1,
+			regionFromSession: snowRegion,
 		},
 	}
 
@@ -425,9 +409,6 @@ func TestNewMetadataService(t *testing.T) {
 				if m.GetNumAttachedENIs() != tc.expectedENIs {
 					t.Errorf("GetMetadata() failed for %s: got %v, expected %v", enisEndpoint, m.GetNumAttachedENIs(), tc.expectedENIs)
 				}
-				if m.GetNumBlockDeviceMappings() != tc.expectedBlockDevices {
-					t.Errorf("GetMetadata() failed for %s: got %v, expected %v", blockDevicesEndpoint, m.GetNumBlockDeviceMappings(), tc.expectedBlockDevices)
-				}
 			}
 			mockCtrl.Finish()
 		})

pkg/driver/node.go

@@ -777,7 +777,6 @@ func (d *nodeService) getVolumesLimit() int64 {
 
 	isNitro := cloud.IsNitroInstanceType(instanceType)
 	availableAttachments := cloud.GetMaxAttachments(isNitro)
-	blockVolumes := d.metadata.GetNumBlockDeviceMappings()
 	dedicatedLimit := cloud.GetDedicatedLimitForInstanceType(instanceType)
 
 	// For special dedicated limit instance types, the limit is only for EBS volumes
@@ -789,7 +788,7 @@ func (d *nodeService) getVolumesLimit() int64 {
 		nvmeInstanceStoreVolumes := cloud.GetNVMeInstanceStoreVolumesForInstanceType(instanceType)
 		availableAttachments = availableAttachments - enis - nvmeInstanceStoreVolumes
 	}
-	availableAttachments = availableAttachments - blockVolumes - 1 // -1 for root device
+	availableAttachments = availableAttachments - 1 // -1 for root device
 	if availableAttachments < 0 {
 		availableAttachments = 0
 	}

pkg/driver/node_test.go

@@ -2025,7 +2025,6 @@ func TestNodeGetInfo(t *testing.T) {
 		availabilityZone  string
 		region            string
 		attachedENIs      int
-		blockDevices      int
 		volumeAttachLimit int64
 		expMaxVolumes     int64
 		outpostArn        arn.ARN
@@ -2137,54 +2136,6 @@ func TestNodeGetInfo(t *testing.T) {
 			expMaxVolumes:     11,
 			outpostArn:        emptyOutpostArn,
 		},
-		{
-			name:              "nitro instances already attached EBS volumes",
-			instanceID:        "i-123456789abcdef01",
-			instanceType:      "t3.xlarge",
-			availabilityZone:  "us-west-2b",
-			region:            "us-west-2",
-			volumeAttachLimit: -1,
-			attachedENIs:      1,
-			blockDevices:      2,
-			expMaxVolumes:     24,
-			outpostArn:        emptyOutpostArn,
-		},
-		{
-			name:              "nitro instance already attached max EBS volumes",
-			instanceID:        "i-123456789abcdef01",
-			instanceType:      "t3.xlarge",
-			availabilityZone:  "us-west-2b",
-			region:            "us-west-2",
-			volumeAttachLimit: -1,
-			attachedENIs:      1,
-			blockDevices:      27,
-			expMaxVolumes:     0,
-			outpostArn:        emptyOutpostArn,
-		},
-		{
-			name:              "non-nitro instance already attached max EBS volumes",
-			instanceID:        "i-123456789abcdef01",
-			instanceType:      "m5.xlarge",
-			availabilityZone:  "us-west-2b",
-			region:            "us-west-2",
-			volumeAttachLimit: -1,
-			attachedENIs:      1,
-			blockDevices:      39,
-			expMaxVolumes:     0,
-			outpostArn:        emptyOutpostArn,
-		},
-		{
-			name:              "nitro instance already attached max ENIs",
-			instanceID:        "i-123456789abcdef01",
-			instanceType:      "t3.xlarge",
-			availabilityZone:  "us-west-2b",
-			region:            "us-west-2",
-			volumeAttachLimit: -1,
-			attachedENIs:      27,
-			blockDevices:      1,
-			expMaxVolumes:     0,
-			outpostArn:        emptyOutpostArn,
-		},
 		{
 			name:              "nitro instance with dedicated limit",
 			instanceID:        "i-123456789abcdef01",
@@ -2217,7 +2168,6 @@ func TestNodeGetInfo(t *testing.T) {
 
 			if tc.volumeAttachLimit < 0 {
 				mockMetadata.EXPECT().GetInstanceType().Return(tc.instanceType)
-				mockMetadata.EXPECT().GetNumBlockDeviceMappings().Return(tc.blockDevices)
 				if cloud.IsNitroInstanceType(tc.instanceType) && cloud.GetDedicatedLimitForInstanceType(tc.instanceType) == 0 {
 					mockMetadata.EXPECT().GetNumAttachedENIs().Return(tc.attachedENIs)
 				}