Bug 1810470:Make EBS controllerexpansion idempotent

pkg/cloud/cloud.go

@@ -860,6 +860,20 @@ func (c *cloud) ResizeDisk(ctx context.Context, volumeID string, newSizeBytes in
 		return oldSizeGiB, nil
 	}
 
+	latestMod, err := c.getLatestVolumeModification(ctx, volumeID)
+	// if there are no errors fetching modifications
+	if err == nil && latestMod != nil {
+		state := aws.StringValue(latestMod.ModificationState)
+		targetSize := aws.Int64Value(latestMod.TargetSize)
+		if (state == ec2.VolumeModificationStateCompleted || state == ec2.VolumeModificationStateOptimizing) && targetSize >= newSizeGiB {
+			return targetSize, nil
+		}
+
+		if state == ec2.VolumeModificationStateModifying {
+			return oldSizeGiB, fmt.Errorf("volume %q is still being expanded to size %d", volumeID, targetSize)
+		}
+	}
+
 	req := &ec2.ModifyVolumeInput{
 		VolumeId: aws.String(volumeID),
 		Size:     aws.Int64(newSizeGiB),
@@ -893,10 +907,11 @@ func (c *cloud) ResizeDisk(ctx context.Context, volumeID string, newSizeBytes in
 
 // waitForVolumeSize waits for a volume modification to finish and return its size.
 func (c *cloud) waitForVolumeSize(ctx context.Context, volumeID string) (int64, error) {
+	// the default context is 10s and hence we should reduce this to more reasonable value and let external-resizer retry
 	backoff := wait.Backoff{
 		Duration: 1 * time.Second,
 		Factor:   1.8,
-		Steps:    20,
+		Steps:    3,
 	}
 
 	var modVolSizeGiB int64

pkg/cloud/cloud_test.go

@@ -659,6 +659,26 @@ func TestResizeDisk(t *testing.T) {
 			reqSizeGiB: 2,
 			expErr:     nil,
 		},
+		{
+			name:     "success: with previous expansion",
+			volumeID: "vol-test",
+			existingVolume: &ec2.Volume{
+				VolumeId:         aws.String("vol-test"),
+				Size:             aws.Int64(1),
+				AvailabilityZone: aws.String(defaultZone),
+			},
+			descModVolume: &ec2.DescribeVolumesModificationsOutput{
+				VolumesModifications: []*ec2.VolumeModification{
+					{
+						VolumeId:          aws.String("vol-test"),
+						TargetSize:        aws.Int64(2),
+						ModificationState: aws.String(ec2.VolumeModificationStateCompleted),
+					},
+				},
+			},
+			reqSizeGiB: 2,
+			expErr:     nil,
+		},
 		{
 			name:                "fail: volume doesn't exist",
 			volumeID:            "vol-test",
@@ -707,6 +727,9 @@ func TestResizeDisk(t *testing.T) {
 			}
 			if tc.descModVolume != nil {
 				mockEC2.EXPECT().DescribeVolumesModificationsWithContext(gomock.Eq(ctx), gomock.Any()).Return(tc.descModVolume, nil).AnyTimes()
+			} else {
+				emptyOutput := &ec2.DescribeVolumesModificationsOutput{}
+				mockEC2.EXPECT().DescribeVolumesModificationsWithContext(gomock.Eq(ctx), gomock.Any()).Return(emptyOutput, nil).AnyTimes()
 			}
 
 			newSize, err := c.ResizeDisk(ctx, tc.volumeID, util.GiBToBytes(tc.reqSizeGiB))