Add image in GCP only if its a boot disk

Author: ngopalak-redhat

pkg/webhooks/machine_webhook.go

@@ -1372,7 +1372,7 @@ func defaultGCPDisks(disks []*machinev1beta1.GCPDisk, clusterID string) []*machi
 			disk.Type = defaultGCPDiskType
 		}
 
-		if disk.Image == "" {
+		if disk.Boot && disk.Image == "" {
 			disk.Image = defaultGCPDiskImage()
 		}
 	}

pkg/webhooks/machine_webhook_test.go

@@ -5124,6 +5124,39 @@ func TestDefaultGCPProviderSpec(t *testing.T) {
 			expectedError:    "",
 			expectedWarnings: itWarnings,
 		},
+		{
+			testCase: "non-boot disk without image remains empty",
+			providerSpec: &machinev1beta1.GCPMachineProviderSpec{
+				Disks: []*machinev1beta1.GCPDisk{
+					{
+						Boot:  true,
+						Image: "custom-boot-image",
+					},
+					{
+						Boot:   false,
+						SizeGB: 100,
+					},
+				},
+			},
+			modifyDefault: func(p *machinev1beta1.GCPMachineProviderSpec) {
+				p.Disks = []*machinev1beta1.GCPDisk{
+					{
+						Boot:  true,
+						Image: "custom-boot-image",
+						Type:  defaultGCPDiskType,
+					},
+					{
+						Boot:   false,
+						SizeGB: 100,
+						Type:   defaultGCPDiskType,
+						Image:  "",
+					},
+				}
+			},
+			expectedOk:       true,
+			expectedError:    "",
+			expectedWarnings: itWarnings,
+		},
 	}
 
 	platformStatus := &osconfigv1.PlatformStatus{