Changes to the error message displayed during the removal of public templates that are used (apache#12373)

Author: erikbocks

server/src/main/java/com/cloud/template/TemplateManagerImpl.java

@@ -222,7 +222,6 @@
 import com.cloud.vm.VmDetailConstants;
 import com.cloud.vm.dao.UserVmDao;
 import com.cloud.vm.dao.VMInstanceDao;
-import com.google.common.base.Joiner;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 
@@ -1389,9 +1388,16 @@ public boolean deleteTemplate(DeleteTemplateCmd cmd) {
         else {
             vmInstanceVOList = _vmInstanceDao.listNonExpungedByTemplate(templateId);
         }
-        if(!cmd.isForced() && CollectionUtils.isNotEmpty(vmInstanceVOList)) {
-            final String message = String.format("Unable to delete Template: %s because Instance: [%s] are using it.",  template, Joiner.on(",").join(vmInstanceVOList));
-            logger.warn(message);
+        if (!cmd.isForced() && CollectionUtils.isNotEmpty(vmInstanceVOList)) {
+            String message = String.format("Unable to delete template [%s] because there are [%d] VM instances using it.", template, vmInstanceVOList.size());
+            String instancesListMessage = String.format(" Instances list: [%s].", StringUtils.join(vmInstanceVOList, ","));
+
+            logger.warn("{}{}", message, instancesListMessage);
+
+            if (_accountMgr.isRootAdmin(caller.getAccountId())) {
+                message += instancesListMessage;
+            }
+
             throw new InvalidParameterValueException(message);
         }