Azure: mount default provisioning iso before try device listing (#870)

With a few exceptions, Azure VM deployments receive provisioning
metadata through the provisioning iso presented as a cdrom device
(/dev/sr0). The existing code attempts to find this device by calling
blkid to find all devices that have either type iso9660 or udf. This
can be very expensive if the VM has a lot of disks. This commit will
attempt to mount the default iso location first and only tries to use
blkid to locate the iso location if the default mounting location fails

1 files changed, 40 insertions, 12 deletions

diff --git a/tests/unittests/test_datasource/test_azure.py b/tests/unittests/test_datasource/test_azure.py
index 54e06119..3bf8fdb2 100644
--- a/tests/unittests/test_datasource/test_azure.py
+++ b/tests/unittests/test_datasource/test_azure.py
@@ -635,15 +635,20 @@ scbus-1 on xpt0 bus 0
     def _get_ds(self, data, agent_command=None, distro='ubuntu',
                 apply_network=None, instance_id=None):
 
-        def dsdevs():
-            return data.get('dsdevs', [])
-
         def _wait_for_files(flist, _maxwait=None, _naplen=None):
             data['waited'] = flist
             return []
 
+        def _load_possible_azure_ds(seed_dir, cache_dir):
+            yield seed_dir
+            yield dsaz.DEFAULT_PROVISIONING_ISO_DEV
+            yield from data.get('dsdevs', [])
+            if cache_dir:
+                yield cache_dir
+
+        seed_dir = os.path.join(self.paths.seed_dir, "azure")
         if data.get('ovfcontent') is not None:
-            populate_dir(os.path.join(self.paths.seed_dir, "azure"),
+            populate_dir(seed_dir,
                          {'ovf-env.xml': data['ovfcontent']})
 
         dsaz.BUILTIN_DS_CONFIG['data_dir'] = self.waagent_d
@@ -654,6 +659,8 @@ scbus-1 on xpt0 bus 0
         self.m_report_failure_to_fabric = mock.MagicMock(autospec=True)
         self.m_ephemeral_dhcpv4 = mock.MagicMock()
         self.m_ephemeral_dhcpv4_with_reporting = mock.MagicMock()
+        self.m_list_possible_azure_ds = mock.MagicMock(
+            side_effect=_load_possible_azure_ds)
 
         if instance_id:
             self.instance_id = instance_id
@@ -667,7 +674,8 @@ scbus-1 on xpt0 bus 0
                 return '7783-7084-3265-9085-8269-3286-77'
 
         self.apply_patches([
-            (dsaz, 'list_possible_azure_ds_devs', dsdevs),
+            (dsaz, 'list_possible_azure_ds',
+                self.m_list_possible_azure_ds),
             (dsaz, 'perform_hostname_bounce', mock.MagicMock()),
             (dsaz, 'get_hostname', mock.MagicMock()),
             (dsaz, 'set_hostname', mock.MagicMock()),
@@ -844,9 +852,14 @@ scbus-1 on xpt0 bus 0
         """When a device path is used, present that in subplatform."""
         data = {'sys_cfg': {}, 'dsdevs': ['/dev/cd0']}
         dsrc = self._get_ds(data)
+        # DSAzure will attempt to mount /dev/sr0 first, which should
+        # fail with mount error since the list of devices doesn't have
+        # /dev/sr0
         with mock.patch(MOCKPATH + 'util.mount_cb') as m_mount_cb:
-            m_mount_cb.return_value = (
-                {'local-hostname': 'me'}, 'ud', {'cfg': ''}, {})
+            m_mount_cb.side_effect = [
+                MountFailedError("fail"),
+                ({'local-hostname': 'me'}, 'ud', {'cfg': ''}, {})
+            ]
             self.assertTrue(dsrc.get_data())
         self.assertEqual(dsrc.userdata_raw, 'ud')
         self.assertEqual(dsrc.metadata['local-hostname'], 'me')
@@ -1608,12 +1621,19 @@ scbus-1 on xpt0 bus 0
 
     @mock.patch(MOCKPATH + 'util.is_FreeBSD')
     @mock.patch(MOCKPATH + '_check_freebsd_cdrom')
-    def test_list_possible_azure_ds_devs(self, m_check_fbsd_cdrom,
-                                         m_is_FreeBSD):
+    def test_list_possible_azure_ds(self, m_check_fbsd_cdrom,
+                                    m_is_FreeBSD):
         """On FreeBSD, possible devs should show /dev/cd0."""
         m_is_FreeBSD.return_value = True
         m_check_fbsd_cdrom.return_value = True
-        self.assertEqual(dsaz.list_possible_azure_ds_devs(), ['/dev/cd0'])
+        possible_ds = []
+        for src in dsaz.list_possible_azure_ds(
+                "seed_dir", "cache_dir"):
+            possible_ds.append(src)
+        self.assertEqual(possible_ds, ["seed_dir",
+                                       dsaz.DEFAULT_PROVISIONING_ISO_DEV,
+                                       "/dev/cd0",
+                                       "cache_dir"])
         self.assertEqual(
             [mock.call("/dev/cd0")], m_check_fbsd_cdrom.call_args_list)
 
@@ -1967,11 +1987,19 @@ class TestAzureBounce(CiTestCase):
     with_logs = True
 
     def mock_out_azure_moving_parts(self):
+
+        def _load_possible_azure_ds(seed_dir, cache_dir):
+            yield seed_dir
+            yield dsaz.DEFAULT_PROVISIONING_ISO_DEV
+            if cache_dir:
+                yield cache_dir
+
         self.patches.enter_context(
             mock.patch.object(dsaz.util, 'wait_for_files'))
         self.patches.enter_context(
-            mock.patch.object(dsaz, 'list_possible_azure_ds_devs',
-                              mock.MagicMock(return_value=[])))
+            mock.patch.object(
+                dsaz, 'list_possible_azure_ds',
+                mock.MagicMock(side_effect=_load_possible_azure_ds)))
         self.patches.enter_context(
             mock.patch.object(dsaz, 'get_metadata_from_fabric',
                               mock.MagicMock(return_value={})))