Reorder root disk as first disk in OSMorphing stage

Author: Dany9966

coriolis/tasks/osmorphing_tasks.py

@@ -1,6 +1,8 @@
 # Copyright 2016 Cloudbase Solutions Srl
 # All Rights Reserved.
 
+import re
+
 from oslo_log import log as logging
 
 from coriolis import constants
@@ -14,6 +16,35 @@
 LOG = logging.getLogger(__name__)
 
 
+def _reorder_root_disk(volumes_info, root_device):
+    """
+    Reorders volumes_info so that the root disk will always be the first volume
+
+    root_device is returned by the osmount tools as the root partition device
+    (i.e. /dev/vdd2). We need to strip the trailing digits to get the actual
+    disk device. After that, we convert the last letter of the disk device name
+    into the equivalent index by alphabetical order (starting with 0, so 'a' -> 0).
+    Then we just swap the indexes in the volumes_info list.
+    """
+    if not root_device:
+        LOG.warn('os_root_dev was not returned by OSMount Tools. '
+                 'Skipping root disk reordering')
+        return
+
+    pattern = r'[0-9]'
+    root_disk = re.sub(pattern, '', root_device)
+    disk_nmb = ord(root_disk[-1]) - 98
+    if disk_nmb:
+        if disk_nmb < len(volumes_info):
+            volumes_info[0], volumes_info[disk_nmb] = (
+                volumes_info[disk_nmb], volumes_info[0])
+        else:
+            LOG.warn('Disk device name index out of range: %s for device %s'
+                     'Skipping root disk reordering', disk_nmb, root_disk)
+            return
+
+
+
 class OSMorphingTask(base.TaskRunner):
 
     @classmethod
@@ -28,7 +59,7 @@ def get_required_task_info_properties(cls):
 
     @classmethod
     def get_returned_task_info_properties(cls):
-        return []
+        return ["instance_deployment_info"]
 
     @classmethod
     def get_required_provider_types(cls):
@@ -53,6 +84,7 @@ def _run(self, ctxt, instance, origin, destination, task_info,
         osmorphing_connection_info = base.unmarshal_migr_conn_info(
             task_info['osmorphing_connection_info'])
         osmorphing_info = task_info.get('osmorphing_info', {})
+        instance_deployment_info = task_info.get('instance_deployment_info', {})
 
         user_scripts = task_info.get("user_scripts")
         instance_script = None
@@ -72,7 +104,13 @@ def _run(self, ctxt, instance, origin, destination, task_info,
             instance_script,
             event_handler)
 
-        return {}
+        volumes_info = instance_deployment_info.get('volumes_info', [])
+        LOG.debug('Volumes info before root disk reordering: %s', volumes_info)
+        _reorder_root_disk(volumes_info, osmorphing_info.get('os_root_dev'))
+        LOG.debug('Volumes info after root disk reordering: %s', volumes_info)
+
+        return {
+            'instance_deployment_info': instance_deployment_info}
 
 
 class DeployOSMorphingResourcesTask(base.TaskRunner):