Add VSS fallback (#11)

* Add VSS fallback

* Add changes to Changelog

* Increment version

Author: lancefogle

Changelog.md

@@ -1,6 +1,10 @@
 # Changelog for OnyxBackupVM
 ### VM Backup for XenServer/XCP-NG
 
+### v1.2.1 - ??
+  #### Features and Enhancements
+  - VSS snapshots should have fallback #10
+
 ### v1.2.0 - 26 June 2018
   #### Bugs
   - Snapshot checking too eager #6

onyxbackup-vm.py

@@ -31,7 +31,7 @@ class Cli(object):
 	def __init__(self):
 		self.logger = getLogger('onyxbackup')
 		self.program_name = 'OnyxBackupVM'
-		self.program_version = 'v1.2.0'
+		self.program_version = 'v1.2.1'
 		self.config = self._setup()
 
 	# API Functions

onyxbackup/service/service.py

@@ -830,6 +830,9 @@ def _snapshot(self, uuid, snapshot_type='vm', snap_name='ONYXBACKUP'):
 
 		snap_uuid = self._get_xe_cmd_result(cmd)
 		if not snap_uuid:
+			if snapshot_type == 'vm-vss':
+				self._add_status('warning', '(!) VSS snapshot failed. Falling back to standard snapshot.')
+				return self._snapshot(uuid)
 			self._add_status('error', '(!) Failed to create a snapshot')
 			return False
 		return snap_uuid