Fix GCP disk size conversion

aws/disk.go

@@ -7,8 +7,6 @@ import (
 	"github.com/grafana/unused"
 )
 
-const GiBbytes = 1073741824
-
 var _ unused.Disk = &Disk{}
 
 // Disk holds information about an AWS EC2 volume.
@@ -49,7 +47,7 @@ func (d *Disk) Meta() unused.Meta { return d.meta }
 func (d *Disk) SizeGB() int { return int(*d.Volume.Size) }
 
 // SizeBytes returns the size of this AWS EC2 volume in bytes.
-func (d *Disk) SizeBytes() float64 { return float64(*d.Volume.Size) * GiBbytes }
+func (d *Disk) SizeBytes() float64 { return float64(*d.Volume.Size) * unused.GiBbytes }
 
 // LastUsedAt returns a zero [time.Time] value, as AWS does not
 // provide this information.

aws/disk_test.go

@@ -11,6 +11,7 @@ import (
 
 func TestDisk(t *testing.T) {
 	createdAt := time.Date(2021, 7, 16, 5, 55, 00, 0, time.UTC)
+	size := int32(10)
 
 	for _, keyName := range []string{"Name", "CSIVolumeName"} {
 		t.Run(keyName, func(t *testing.T) {
@@ -24,6 +25,7 @@ func TestDisk(t *testing.T) {
 							Value: aws.String("my-disk"),
 						},
 					},
+					Size: &size,
 				},
 				nil,
 				nil,
@@ -44,6 +46,14 @@ func TestDisk(t *testing.T) {
 			if !createdAt.Equal(d.CreatedAt()) {
 				t.Errorf("expecting CreatedAt() %v, got %v", createdAt, d.CreatedAt())
 			}
+
+			if exp, got := int(size), d.SizeGB(); exp != got {
+				t.Errorf("expecting SizeGB() %d, got %d", exp, got)
+			}
+
+			if exp, got := float64(size) * unused.GiBbytes, d.SizeBytes(); exp != got {
+				t.Errorf("expecting SizeBytes() %f, got %f", exp, got)
+			}
 		})
 	}
 }

azure/disk.go

@@ -27,6 +27,8 @@ func (d *Disk) Provider() unused.Provider { return d.provider }
 func (d *Disk) Name() string { return *d.Disk.Name }
 
 // SizeGB returns the size of this Azure compute disk in GB.
+// Note that Azure uses binary GB, aka, GiB
+// https://learn.microsoft.com/en-us/dotnet/api/microsoft.azure.management.compute.models.datadisk.disksizegb?view=azure-dotnet-legacy
 func (d *Disk) SizeGB() int { return int(*d.Disk.DiskSizeGB) }
 
 // SizeBytes returns the size of this Azure compute disk in bytes.

azure/disk_test.go

@@ -13,6 +13,8 @@ func TestDisk(t *testing.T) {
 	createdAt := time.Date(2021, 7, 16, 5, 55, 00, 0, time.UTC)
 	name := "my-disk"
 	id := "my-disk-id"
+	sizeGB := int32(10)
+	sizeBytes := int64(10_737_418_240)
 
 	var d unused.Disk = &Disk{
 		compute.Disk{
@@ -23,6 +25,8 @@ func TestDisk(t *testing.T) {
 			},
 			DiskProperties: &compute.DiskProperties{
 				TimeCreated: &date.Time{Time: createdAt},
+				DiskSizeGB: &sizeGB,
+				DiskSizeBytes: &sizeBytes,
 			},
 		},
 		nil,
@@ -49,6 +53,14 @@ func TestDisk(t *testing.T) {
 		t.Errorf("expecting CreatedAt() %v, got %v", createdAt, d.CreatedAt())
 	}
 
+	if exp, got := int(sizeGB), d.SizeGB(); exp != got {
+		t.Errorf("expecting SizeGB() %d, got %d", exp, got)
+	}
+
+	if exp, got := float64(sizeBytes), d.SizeBytes(); exp != got {
+		t.Errorf("expecting SizeBytes() %f, got %f", exp, got)
+	}
+
 	if !d.LastUsedAt().IsZero() {
 		t.Errorf("Azure doesn't provide a last usage timestamp for disks, got %v", d.LastUsedAt())
 	}

disk.go

@@ -41,3 +41,5 @@ const (
 	HDD     DiskType = "hdd"
 	Unknown DiskType = "unknown"
 )
+
+const GiBbytes = 1_073_741_824 // 2^30

gcp/disk.go

@@ -9,8 +9,6 @@ import (
 	compute "google.golang.org/api/compute/v1"
 )
 
-const GBbytes = 1_000_000_000
-
 // ensure we are properly defining the interface
 var _ unused.Disk = &Disk{}
 
@@ -50,11 +48,14 @@ func (d *Disk) LastUsedAt() time.Time {
 	return t
 }
 
-// SizeGB returns the size of the GCP compute disk in GB.
+// SizeGB returns the size of the GCP compute disk in binary GB (aka GiB).
+// GCP Storage docs: https://cloud.google.com/compute/docs/disks
+// GCP pricing docs: https://cloud.google.com/compute/disks-image-pricing
+// Note that it specifies the use of JEDEC binary gigabytes for the disk size.
 func (d *Disk) SizeGB() int { return int(d.Disk.SizeGb) }
 
 // SizeBytes returns the size of the GCP compute disk in bytes.
-func (d *Disk) SizeBytes() float64 { return float64(d.Disk.SizeGb) * GBbytes }
+func (d *Disk) SizeBytes() float64 { return float64(d.Disk.SizeGb) * unused.GiBbytes }
 
 // DiskType Type returns the type of the GCP compute disk.
 func (d *Disk) DiskType() unused.DiskType {

gcp/disk_test.go

@@ -12,13 +12,15 @@ import (
 func TestDisk(t *testing.T) {
 	createdAt := time.Date(2021, 7, 16, 5, 55, 00, 0, time.UTC)
 	detachedAt := createdAt.Add(1 * time.Hour)
+	size := 10
 
 	var d unused.Disk = &Disk{
 		&compute.Disk{
 			Id:                  1234,
 			Name:                "my-disk",
 			CreationTimestamp:   createdAt.Format(time.RFC3339),
 			LastDetachTimestamp: detachedAt.Format(time.RFC3339),
+			SizeGb:              int64(size),
 		},
 		nil,
 		unused.Meta{"foo": "bar"},
@@ -44,6 +46,14 @@ func TestDisk(t *testing.T) {
 		t.Errorf("expecting LastUsedAt() %v, got %v", detachedAt, d.LastUsedAt())
 	}
 
+	if exp, got := size, d.SizeGB(); exp != got {
+		t.Errorf("expecting SizeGB() %d, got %d", exp, got)
+	}
+
+	if exp, got := float64(size) * unused.GiBbytes, d.SizeBytes(); exp != got {
+		t.Errorf("expecting SizeBytes() %f, got %f", exp, got)
+	}
+
 	err := unusedtest.AssertEqualMeta(unused.Meta{"foo": "bar"}, d.Meta())
 	if err != nil {
 		t.Fatalf("metadata doesn't match: %v", err)

unusedtest/disk.go

@@ -8,8 +8,6 @@ import (
 
 var _ unused.Disk = Disk{}
 
-const GBbytes = 1_000_000_000
-
 // Disk implements [unused.Disk] for testing purposes.
 type Disk struct {
 	id, name  string
@@ -32,5 +30,5 @@ func (d Disk) CreatedAt() time.Time      { return d.createdAt }
 func (d Disk) Meta() unused.Meta         { return d.meta }
 func (d Disk) LastUsedAt() time.Time     { return d.createdAt.Add(1 * time.Minute) }
 func (d Disk) SizeGB() int               { return d.size }
-func (d Disk) SizeBytes() float64        { return float64(d.size) * GBbytes }
+func (d Disk) SizeBytes() float64        { return float64(d.size) * unused.GiBbytes }
 func (d Disk) DiskType() unused.DiskType { return d.diskType }