server: Fix #6263 Cannot scale VM with custom offering (#6267)

* When scaling with custom offering, which changes only CPU/Memory and keeps same disk offering an exception is thrown.

This commit fixes such cases by checking if the operation is happening on a custom service offering.

* Improve the unit tests that cover null objects.

server/src/main/java/com/cloud/storage/VolumeApiServiceImpl.java

@@ -1705,6 +1705,12 @@ public class VolumeApiServiceImpl extends ManagerBase implements VolumeApiServic
         boolean volumeMigrateRequired = false;
         boolean volumeResizeRequired = false;
 
+        // Skip the Disk offering change on Volume if Disk Offering is the same and is linked to a custom Service Offering
+        if(isNewDiskOfferingTheSameAndCustomServiceOffering(existingDiskOffering, newDiskOffering)) {
+            s_logger.debug(String.format("Scaling CPU and/or Memory of VM with custom service offering. New disk offering stills the same. Skipping the Disk offering change on Volume %s.", volume.getUuid()));
+            return volume;
+        }
+
         // VALIDATIONS
         Long[] updateNewSize = {newSize};
         Long[] updateNewMinIops = {newMinIops};
@@ -1796,6 +1802,19 @@ public class VolumeApiServiceImpl extends ManagerBase implements VolumeApiServic
         return volume;
     }
 
+    /**
+     * Returns true if the new disk offering is the same than current offering, and the respective Service offering is a custom (constraint or unconstraint) offering.
+     */
+    protected boolean isNewDiskOfferingTheSameAndCustomServiceOffering(DiskOfferingVO existingDiskOffering, DiskOfferingVO newDiskOffering) {
+        if (newDiskOffering.getId() == existingDiskOffering.getId()) {
+            ServiceOfferingVO serviceOffering = _serviceOfferingDao.findServiceOfferingByComputeOnlyDiskOffering(newDiskOffering.getId());
+            if (serviceOffering != null && serviceOffering.isCustomized()) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     private VolumeVO resizeVolumeInternal(VolumeVO volume, DiskOfferingVO newDiskOffering, Long currentSize, Long newSize, Long newMinIops, Long newMaxIops, Integer newHypervisorSnapshotReserve, boolean shrinkOk) throws ResourceAllocationException {
         UserVmVO userVm = _userVmDao.findById(volume.getInstanceId());
         HypervisorType hypervisorType = _volsDao.getHypervisorType(volume.getId());
@@ -1896,11 +1915,11 @@ public class VolumeApiServiceImpl extends ManagerBase implements VolumeApiServic
         }
 
         if (newDiskOffering.getId() == existingDiskOffering.getId()) {
-            throw new InvalidParameterValueException(String.format("Volume %s already have the new disk offering %s provided", volume.getUuid(), existingDiskOffering.getUuid()));
+            throw new InvalidParameterValueException(String.format("Volume %s already have the new disk offering %s provided.", volume.getUuid(), existingDiskOffering.getUuid()));
         }
 
         if (existingDiskOffering.getDiskSizeStrictness() != newDiskOffering.getDiskSizeStrictness()) {
-            throw new InvalidParameterValueException("Disk offering size strictness does not match with new disk offering");
+            throw new InvalidParameterValueException("Disk offering size strictness does not match with new disk offering.");
         }
 
         if (MatchStoragePoolTagsWithDiskOffering.valueIn(volume.getDataCenterId())) {

server/src/test/java/com/cloud/storage/VolumeApiServiceImplTest.java

@@ -1156,4 +1156,48 @@ public class VolumeApiServiceImplTest {
         boolean result = volumeApiServiceImpl.isNotPossibleToResize(volume, diskOffering);
         Assert.assertEquals(expectedIsNotPossibleToResize, result);
     }
+
+    @Test
+    public void isNewDiskOfferingTheSameAndCustomServiceOfferingTestDifferentOfferings() {
+        prepareAndRunIsNewDiskOfferingTheSameAndCustomServiceOffering(1l, 2l, false, true, false);
+    }
+
+    @Test
+    public void isNewDiskOfferingTheSameAndCustomServiceOfferingTestDifferentOfferingsCustom() {
+        prepareAndRunIsNewDiskOfferingTheSameAndCustomServiceOffering(1l, 2l, true, true, false);
+    }
+
+    @Test
+    public void isNewDiskOfferingTheSameAndCustomServiceOfferingTestSameOfferingsCustom() {
+        prepareAndRunIsNewDiskOfferingTheSameAndCustomServiceOffering(1l, 1l, true, true, true);
+    }
+
+    @Test
+    public void isNewDiskOfferingTheSameAndCustomServiceOfferingTestSameOfferingsNotCustom() {
+        prepareAndRunIsNewDiskOfferingTheSameAndCustomServiceOffering(1l, 1l, false, true, false);
+    }
+
+    @Test
+    public void isNewDiskOfferingTheSameAndCustomServiceOfferingTestDifferentOfferingsAndNullOffering() {
+        prepareAndRunIsNewDiskOfferingTheSameAndCustomServiceOffering(1l, 2l, true, false, false);
+    }
+    @Test
+    public void isNewDiskOfferingTheSameAndCustomServiceOfferingTestSameOfferingsNullOffering() {
+        prepareAndRunIsNewDiskOfferingTheSameAndCustomServiceOffering(1l, 1l, false, false, false);
+    }
+
+    private void prepareAndRunIsNewDiskOfferingTheSameAndCustomServiceOffering(long existingDiskOfferingId, long newDiskOfferingId, boolean isCustomized,
+            boolean isNotNullServiceOffering, boolean expectedResult) {
+        DiskOfferingVO existingDiskOffering = Mockito.mock(DiskOfferingVO.class);
+        when(existingDiskOffering.getId()).thenReturn(existingDiskOfferingId);
+        DiskOfferingVO newDiskOffering = Mockito.mock(DiskOfferingVO.class);
+        when(newDiskOffering.getId()).thenReturn(newDiskOfferingId);
+        if(isNotNullServiceOffering) {
+            ServiceOfferingVO serviceOfferingVO = Mockito.mock(ServiceOfferingVO.class);
+            when(serviceOfferingVO.isCustomized()).thenReturn(isCustomized);
+            when(serviceOfferingDao.findServiceOfferingByComputeOnlyDiskOffering(anyLong())).thenReturn(serviceOfferingVO);
+        }
+        boolean result = volumeApiServiceImpl.isNewDiskOfferingTheSameAndCustomServiceOffering(existingDiskOffering, newDiskOffering);
+        Assert.assertEquals(expectedResult, result);
+    }
 }