2 files changed, 46 insertions, 0 deletions
diff --git a/cloudinit/distros/networking.py b/cloudinit/distros/networking.py
index e407fa29..c291196a 100644
--- a/cloudinit/distros/networking.py
+++ b/cloudinit/distros/networking.py
@@ -2,6 +2,7 @@ import abc
 import logging
 import os
 
+from cloudinit import subp
 from cloudinit import net, util
 
 
@@ -175,6 +176,10 @@ class Networking(metaclass=abc.ABCMeta):
         if strict:
             raise RuntimeError(msg)
 
+    @abc.abstractmethod
+    def try_set_link_up(self, devname: DeviceName) -> bool:
+        """Try setting the link to up explicitly and return if it is up."""
+
 
 class BSDNetworking(Networking):
     """Implementation of networking functionality shared across BSDs."""
@@ -185,6 +190,9 @@ class BSDNetworking(Networking):
     def settle(self, *, exists=None) -> None:
         """BSD has no equivalent to `udevadm settle`; noop."""
 
+    def try_set_link_up(self, devname: DeviceName) -> bool:
+        raise NotImplementedError()
+
 
 class LinuxNetworking(Networking):
     """Implementation of networking functionality common to Linux distros."""
@@ -214,3 +222,10 @@ class LinuxNetworking(Networking):
         if exists is not None:
             exists = net.sys_dev_path(exists)
         util.udevadm_settle(exists=exists)
+
+    def try_set_link_up(self, devname: DeviceName) -> bool:
+        """Try setting the link to up explicitly and return if it is up.
+           Not guaranteed to bring the interface up. The caller is expected to
+           add wait times before retrying."""
+        subp.subp(['ip', 'link', 'set', devname, 'up'])
+        return self.is_up(devname)
diff --git a/cloudinit/distros/tests/test_networking.py b/cloudinit/distros/tests/test_networking.py
index b9a63842..ec508f4d 100644
--- a/cloudinit/distros/tests/test_networking.py
+++ b/cloudinit/distros/tests/test_networking.py
@@ -30,6 +30,9 @@ def generic_networking_cls():
         def settle(self, *args, **kwargs):
             raise NotImplementedError
 
+        def try_set_link_up(self, *args, **kwargs):
+            raise NotImplementedError
+
     error = AssertionError("Unexpectedly used /sys in generic networking code")
     with mock.patch(
         "cloudinit.net.get_sys_class_path", side_effect=error,
@@ -74,6 +77,34 @@ class TestLinuxNetworkingIsPhysical:
         assert LinuxNetworking().is_physical(devname)
 
 
+class TestBSDNetworkingTrySetLinkUp:
+    def test_raises_notimplementederror(self):
+        with pytest.raises(NotImplementedError):
+            BSDNetworking().try_set_link_up("eth0")
+
+
+@mock.patch("cloudinit.net.is_up")
+@mock.patch("cloudinit.distros.networking.subp.subp")
+class TestLinuxNetworkingTrySetLinkUp:
+    def test_calls_subp_return_true(self, m_subp, m_is_up):
+        devname = "eth0"
+        m_is_up.return_value = True
+        is_success = LinuxNetworking().try_set_link_up(devname)
+
+        assert (mock.call(['ip', 'link', 'set', devname, 'up']) ==
+                m_subp.call_args_list[-1])
+        assert is_success
+
+    def test_calls_subp_return_false(self, m_subp, m_is_up):
+        devname = "eth0"
+        m_is_up.return_value = False
+        is_success = LinuxNetworking().try_set_link_up(devname)
+
+        assert (mock.call(['ip', 'link', 'set', devname, 'up']) ==
+                m_subp.call_args_list[-1])
+        assert not is_success
+
+
 class TestBSDNetworkingSettle:
     def test_settle_doesnt_error(self):
         # This also implicitly tests that it doesn't use subp.subp