sources/azure: only wait for primary nic to be attached during restore

cloudinit/sources/DataSourceAzure.py

@@ -1068,22 +1068,16 @@ def network_metadata_exc_cb(msg, exc):
         return is_primary, expected_nic_count
 
     @azure_ds_telemetry_reporter
-    def _wait_for_hot_attached_nics(self, nl_sock):
-        """Wait until all the expected nics for the vm are hot-attached.
-        The expected nic count is obtained by requesting the network metadata
-        from IMDS.
-        """
-        LOG.info("Waiting for nics to be hot-attached")
+    def _wait_for_hot_attached_primary_nic(self, nl_sock):
+        """Wait until the primary nic for the vm is hot-attached."""
+        LOG.info("Waiting for primary nic to be hot-attached")
         try:
-            # Wait for nics to be attached one at a time, until we know for
-            # sure that all nics have been attached.
             nics_found = []
             primary_nic_found = False
-            expected_nic_count = -1
 
             # Wait for netlink nic attach events. After the first nic is
             # attached, we are already in the customer vm deployment path and
-            # so eerything from then on should happen fast and avoid
+            # so everything from then on should happen fast and avoid
             # unnecessary delays wherever possible.
             while True:
                 ifname = None
@@ -1114,17 +1108,13 @@ def _wait_for_hot_attached_nics(self, nl_sock):
                 # won't be in primary_nic_found = false state for long.
                 if not primary_nic_found:
                     LOG.info("Checking if %s is the primary nic", ifname)
-                    (
-                        primary_nic_found,
-                        expected_nic_count,
-                    ) = self._check_if_nic_is_primary(ifname)
+                    primary_nic_found, _ = self._check_if_nic_is_primary(
+                        ifname
+                    )
 
-                # Exit criteria: check if we've discovered all nics
-                if (
-                    expected_nic_count != -1
-                    and len(nics_found) >= expected_nic_count
-                ):
-                    LOG.info("Found all the nics for this VM.")
+                # Exit criteria: check if we've discovered primary nic
+                if primary_nic_found:
+                    LOG.info("Found primary nic for this VM.")
                     break
 
         except AssertionError as error:
@@ -1144,7 +1134,7 @@ def _wait_for_all_nics_ready(self):
             self._report_ready_for_pps()
             self._teardown_ephemeral_networking()
             self._wait_for_nic_detach(nl_sock)
-            self._wait_for_hot_attached_nics(nl_sock)
+            self._wait_for_hot_attached_primary_nic(nl_sock)
         except netlink.NetlinkCreateSocketError as e:
             report_diagnostic_event(str(e), logger_func=LOG.warning)
             raise

tests/unittests/sources/test_azure.py

@@ -2987,20 +2987,22 @@ def setUp(self):
 
     @mock.patch(MOCKPATH + "util.write_file", autospec=True)
     @mock.patch(MOCKPATH + "DataSourceAzure._report_ready")
-    @mock.patch(MOCKPATH + "DataSourceAzure._wait_for_hot_attached_nics")
+    @mock.patch(
+        MOCKPATH + "DataSourceAzure._wait_for_hot_attached_primary_nic"
+    )
     @mock.patch(MOCKPATH + "DataSourceAzure._wait_for_nic_detach")
     def test_detect_nic_attach_reports_ready_and_waits_for_detach(
         self,
         m_detach,
-        m_wait_for_hot_attached_nics,
+        m_wait_for_hot_attached_primary_nic,
         m_report_ready,
         m_writefile,
     ):
         """Report ready first and then wait for nic detach"""
         dsa = dsaz.DataSourceAzure({}, distro=None, paths=self.paths)
         dsa._wait_for_all_nics_ready()
         self.assertEqual(1, m_report_ready.call_count)
-        self.assertEqual(1, m_wait_for_hot_attached_nics.call_count)
+        self.assertEqual(1, m_wait_for_hot_attached_primary_nic.call_count)
         self.assertEqual(1, m_detach.call_count)
         self.assertEqual(1, m_writefile.call_count)
         m_writefile.assert_called_with(
@@ -3026,7 +3028,8 @@ def test_wait_for_nic_attach_multinic_attach(
         m_report_ready,
         m_writefile,
     ):
-        """Wait for nic attach if we do not have a fallback interface"""
+        """Wait for nic attach if we do not have a fallback interface.
+        Skip waiting for additional nics after we have found primary"""
         dsa = dsaz.DataSourceAzure({}, distro=None, paths=self.paths)
         lease = {
             "interface": "eth9",
@@ -3057,10 +3060,28 @@ def test_wait_for_nic_attach_multinic_attach(
         dsa._wait_for_all_nics_ready()
 
         self.assertEqual(1, m_detach.call_count)
-        self.assertEqual(2, m_attach.call_count)
+        # only wait for primary nic
+        self.assertEqual(1, m_attach.call_count)
         # DHCP and network metadata calls will only happen on the primary NIC.
         self.assertEqual(1, m_dhcpv4.call_count)
         self.assertEqual(1, m_imds.call_count)
+        # no call to bring link up on secondary nic
+        self.assertEqual(1, m_link_up.call_count)
+
+        # reset mock to test again with primary nic being eth1
+        m_detach.reset_mock()
+        m_attach.reset_mock()
+        m_dhcpv4.reset_mock()
+        m_link_up.reset_mock()
+        m_attach.side_effect = ["eth0", "eth1"]
+        m_imds.reset_mock()
+        m_imds.side_effect = [{}, md]
+        dsa = dsaz.DataSourceAzure({}, distro=None, paths=self.paths)
+        dsa._wait_for_all_nics_ready()
+        self.assertEqual(1, m_detach.call_count)
+        self.assertEqual(2, m_attach.call_count)
+        self.assertEqual(2, m_dhcpv4.call_count)
+        self.assertEqual(2, m_imds.call_count)
         self.assertEqual(2, m_link_up.call_count)
 
     @mock.patch("cloudinit.url_helper.time.sleep", autospec=True)