Evacuate VMs from Compute node

In preparation phase of the upgrade of a node, evacuate virtual machines
from that node to other hosts using live migration.

This feature only supported for nodes where live migration is available.

Change-Id: I13a20b884aea1e3058a93f5459955b4d2a8a2089
Related-bug: 1523469

octane/handlers/upgrade/__init__.py

@@ -17,6 +17,7 @@ class UpgradeHandler(object):
     def __init__(self, node, env, isolated):
         self.node = node
         self.orig_env = self.node.env
+        self.orig_version = self.orig_env.data["fuel_version"]
         self.env = env
         self.isolated = isolated
 

octane/handlers/upgrade/compute.py

@@ -32,8 +32,11 @@ class ComputeUpgrade(upgrade.UpgradeHandler):
         if env_util.get_env_provision_method(env) != 'image':
             self.create_configdrive_partition()
             disk.update_node_partition_info(self.node.id)
-        self.backup_iscsi_initiator_info()
-        self.preserve_partition()
+        if node_util.is_live_migration_supported(self.node):
+            self.evacuate_host()
+        else:
+            self.backup_iscsi_initiator_info()
+            self.preserve_partition()
 
     def postdeploy(self):
         self.restore_iscsi_initiator_info()

octane/tests/test_util_node.py

@@ -141,3 +141,24 @@ def test_remove_compute_upgrade_levels(mocker, node, content,
                                        expected_content):
     with _check_upgrade_levels(mocker, node, content, expected_content):
         node_util.remove_compute_upgrade_levels(node)
+
+
+NOVA_LIVE_MIGRATION_FLAG = b"    live_migration_flag="
+NOVA_LIVE_MIGRATION_ENABLED = NOVA_LIVE_MIGRATION_FLAG + \
+    b"FLAG1,VIR_MIGRATE_LIVE,FLAG2\n"
+NOVA_NO_LIVE_MIGRATION_FLAG = b"no_live_migration_flag\n"
+NOVA_EMPTY = b""
+
+
+@pytest.mark.parametrize("content,expected_res", [
+    (NOVA_LIVE_MIGRATION_ENABLED, True),
+    (NOVA_LIVE_MIGRATION_FLAG, False),
+    (NOVA_NO_LIVE_MIGRATION_FLAG, False),
+    (NOVA_EMPTY, False),
+])
+def test_is_live_migration_supported(mocker, node, content, expected_res):
+    mock_sftp = mocker.patch("octane.util.ssh.sftp")
+    mock_sftp.return_value.open.return_value = io.BytesIO(content)
+
+    res = node_util.is_live_migration_supported(node)
+    assert res == expected_res

octane/util/node.py

@@ -137,3 +137,13 @@ def remove_compute_upgrade_levels(node):
             if line.startswith("compute="):
                 continue
             new.write(line)
+
+
+def is_live_migration_supported(node):
+    sftp = ssh.sftp(node)
+    with sftp.open('/etc/nova/nova.conf') as config:
+        for line in config:
+            if line.strip().startswith("live_migration_flag") \
+                    and "VIR_MIGRATE_LIVE" in line:
+                return True
+    return False