Azure: Check if interface is up after sleep when trying to bring it up (#972)

When bringing interface up by unbinding and then binding hv_netvsc
driver, it might take a short delay after binding for the link to be
up. So before trying unbind/bind again after sleep, check if the link
is up. This is a corner case when a preprovisioned VM is reused and
the NICs are hot-attached.

1 files changed, 19 insertions, 0 deletions

diff --git a/tests/unittests/test_datasource/test_azure.py b/tests/unittests/test_datasource/test_azure.py
index 63eaf384..03609c3d 100644
--- a/tests/unittests/test_datasource/test_azure.py
+++ b/tests/unittests/test_datasource/test_azure.py
@@ -2907,6 +2907,25 @@ class TestPreprovisioningHotAttachNics(CiTestCase):
         dsa.wait_for_link_up("eth0")
         self.assertEqual(1, m_is_link_up.call_count)
 
+    @mock.patch(MOCKPATH + 'net.is_up', autospec=True)
+    @mock.patch(MOCKPATH + 'util.write_file')
+    @mock.patch('cloudinit.net.read_sys_net')
+    @mock.patch('cloudinit.distros.networking.LinuxNetworking.try_set_link_up')
+    def test_wait_for_link_up_checks_link_after_sleep(
+            self, m_is_link_up, m_read_sys_net, m_writefile, m_is_up):
+        """Waiting for link to be up should return immediately if the link is
+           already up."""
+
+        distro_cls = distros.fetch('ubuntu')
+        distro = distro_cls('ubuntu', {}, self.paths)
+        dsa = dsaz.DataSourceAzure({}, distro=distro, paths=self.paths)
+        m_is_link_up.return_value = False
+        m_is_up.return_value = True
+
+        dsa.wait_for_link_up("eth0")
+        self.assertEqual(2, m_is_link_up.call_count)
+        self.assertEqual(1, m_is_up.call_count)
+
     @mock.patch(MOCKPATH + 'util.write_file')
     @mock.patch('cloudinit.net.read_sys_net')
     @mock.patch('cloudinit.distros.networking.LinuxNetworking.try_set_link_up')