Add 'keep_configuration' networking config option to internal v1 networking config

cloudinit/config/schemas/schema-network-config-v1.json

@@ -40,6 +40,10 @@
         "accept-ra": {
           "type": "boolean",
           "description": "Whether to accept IPv6 Router Advertisements (RA) on this interface. If unset, it will not be rendered"
+        },
+        "keep_configuration": {
+          "type": "boolean",
+          "description": "Designate the connection as 'critical to the system', meaning that special care will be taken not to release the assigned IP when the daemon is restarted. (only recognized by Netplan renderer)."
         }
       }
     },

cloudinit/net/netplan.py

@@ -481,6 +481,8 @@ def _render_content(self, network_state: NetworkState) -> str:
                     "set-name": ifname,
                     "match": ifcfg.get("match", None),
                 }
+                if "keep_configuration" in ifcfg:
+                    eth["critical"] = ifcfg["keep_configuration"]
                 if eth["match"] is None:
                     macaddr = ifcfg.get("mac_address", None)
                     if macaddr is not None:

cloudinit/net/network_state.py

@@ -428,6 +428,7 @@ def handle_physical(self, command):
                 "accept-ra": accept_ra,
                 "wakeonlan": wakeonlan,
                 "optional": optional,
+                "keep_configuration": command.get("keep_configuration"),
             }
         )
         iface_key = command.get("config_id", command.get("name"))

cloudinit/sources/DataSourceOracle.py

@@ -293,9 +293,15 @@ def network_config(self):
             return self._network_config
 
         set_primary = False
-        # this is v1
         if self._is_iscsi_root():
             self._network_config = self._get_iscsi_config()
+            logging.debug(
+                "Instance is using iSCSI root, setting primary NIC as critical"
+            )
+            # This is necessary for Oracle baremetal instances in case they are
+            # running on an IPv6-only network. Without this, they become
+            # unreachable/unrecoverable after a shutdown.
+            self._network_config["config"][0]["keep_configuration"] = True
         if not self._has_network_config():
             LOG.debug(
                 "Could not obtain network configuration from initramfs. "
@@ -380,65 +386,41 @@ def _add_network_config_from_opc_imds(self, set_primary: bool = False):
             else:
                 network = ipaddress.ip_network(vnic_dict["subnetCidrBlock"])
 
-            if self._network_config["version"] == 1:
-                if is_primary:
-                    if is_ipv6_only:
-                        subnets = [{"type": "dhcp6"}]
-                    else:
-                        subnets = [{"type": "dhcp"}]
+            if is_primary:
+                if is_ipv6_only:
+                    subnets = [{"type": "dhcp6"}]
                 else:
-                    subnets = []
-                    if vnic_dict.get("privateIp"):
-                        subnets.append(
-                            {
-                                "type": "static",
-                                "address": (
-                                    f"{vnic_dict['privateIp']}/"
-                                    f"{network.prefixlen}"
-                                ),
-                            }
-                        )
-                    if vnic_dict.get("ipv6Addresses"):
-                        subnets.append(
-                            {
-                                "type": "static",
-                                "address": (
-                                    f"{vnic_dict['ipv6Addresses'][0]}/"
-                                    f"{network.prefixlen}"
-                                ),
-                            }
-                        )
-                interface_config = {
-                    "name": name,
-                    "type": "physical",
-                    "mac_address": mac_address,
-                    "mtu": MTU,
-                    "subnets": subnets,
-                }
-                self._network_config["config"].append(interface_config)
-            elif self._network_config["version"] == 2:
-                # Why does this elif exist???
-                # Are there plans to switch to v2?
-                interface_config = {
-                    "mtu": MTU,
-                    "match": {"macaddress": mac_address},
-                }
-                self._network_config["ethernets"][name] = interface_config
-
-                interface_config["dhcp6"] = is_primary and is_ipv6_only
-                interface_config["dhcp4"] = is_primary and not is_ipv6_only
-                if not is_primary:
-                    interface_config["addresses"] = []
-                    if vnic_dict.get("privateIp"):
-                        interface_config["addresses"].append(
-                            f"{vnic_dict['privateIp']}/{network.prefixlen}"
-                        )
-                    if vnic_dict.get("ipv6Addresses"):
-                        interface_config["addresses"].append(
-                            f"{vnic_dict['ipv6Addresses'][0]}/"
-                            f"{network.prefixlen}"
-                        )
-                self._network_config["ethernets"][name] = interface_config
+                    subnets = [{"type": "dhcp"}]
+            else:
+                subnets = []
+                if vnic_dict.get("privateIp"):
+                    subnets.append(
+                        {
+                            "type": "static",
+                            "address": (
+                                f"{vnic_dict['privateIp']}/"
+                                f"{network.prefixlen}"
+                            ),
+                        }
+                    )
+                if vnic_dict.get("ipv6Addresses"):
+                    subnets.append(
+                        {
+                            "type": "static",
+                            "address": (
+                                f"{vnic_dict['ipv6Addresses'][0]}/"
+                                f"{network.prefixlen}"
+                            ),
+                        }
+                    )
+            interface_config = {
+                "name": name,
+                "type": "physical",
+                "mac_address": mac_address,
+                "mtu": MTU,
+                "subnets": subnets,
+            }
+            self._network_config["config"].append(interface_config)
 
 
 class DataSourceOracleNet(DataSourceOracle):

doc/rtd/reference/network-config-format-v1.rst

@@ -95,6 +95,15 @@ Physical example
 .. literalinclude:: ../../examples/network-config-v1-physical-3-nic.yaml
    :language: yaml
 
+``keep_configuration: <boolean>``
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Designate the connection as 'critical to the system', meaning that special care
+will be taken not to release the assigned IP when the daemon is restarted.
+
+.. note::
+   This is only recognized by Netplan renderer.
+
 Bond
 ----
 

tests/integration_tests/datasources/test_oci_networking.py

@@ -157,3 +157,50 @@ def test_oci_networking_system_cfg(client: IntegrationInstance, tmpdir):
     netplan_cfg = yaml.safe_load(netplan_yaml)
     expected_netplan_cfg = yaml.safe_load(SYSTEM_CFG)
     assert expected_netplan_cfg == netplan_cfg
+
+
+@pytest.mark.skipif(PLATFORM != "oci", reason="Test is OCI specific")
+def test_oci_keep_configuration_networking_config(
+    session_cloud: IntegrationCloud,
+):
+    """
+    Test to ensure the keep_configuration is applied on Oracle ISCSI instances.
+
+    This test launches a Baremetal OCI instance so that ISCSI is used, and
+    checks that the primary systemd network configuration file contains the
+    'KeepConfiguration=true' directive, which indicates that the network
+    configuration is preserved as expected.
+
+    Assertions:
+    - At least one netplan file exists under '/run/systemd/network'.
+    - The primary systemd network configuration file includes the
+        'KeepConfiguration=true' directive.
+    - The netplan configuration includes the 'critical: true' directive.
+    """
+    with session_cloud.launch(
+        launch_kwargs={
+            "instance_type": "BM.Optimized3.36",
+        },
+    ) as client:
+        r = client.execute("ls /run/systemd/network/10-netplan-*.network")
+        assert r.ok, (
+            "No netplan files found under /run/systemd/network. We are looking"
+            " for netplan files here to check that the underlying "
+            "'KeepConfiguration=true' directive is actually being applied to "
+            "the systemd network configuration."
+        )
+        primary_systemd_file: str = r.stdout.strip().splitlines()[0]
+        systemd_config = client.read_from_file(primary_systemd_file)
+        assert (
+            "KeepConfiguration=true" in systemd_config
+            or "CriticalConnection=true" in systemd_config
+        ), (
+            f"Neither 'KeepConfiguration=true' nor 'CriticalConnection=true' "
+            f"found in '{primary_systemd_file}':\n{primary_systemd_file}"
+        )
+        netplan_config = client.read_from_file(
+            "/etc/netplan/50-cloud-init.yaml",
+        )
+        assert (
+            "critical: true" in netplan_config
+        ), "critical: true not found in netplan config"

tests/unittests/sources/test_oracle.py

@@ -485,48 +485,6 @@ def test_imds_nic_setup_v1(self, set_primary, oracle_ds):
         assert "10.0.0.231/24" == secondary_cfg["subnets"][0]["address"]
         assert "static" == secondary_cfg["subnets"][0]["type"]
 
-    @pytest.mark.parametrize(
-        "set_primary",
-        [True, False],
-    )
-    def test_secondary_nic_v2(self, set_primary, oracle_ds):
-        oracle_ds._vnics_data = json.loads(OPC_VM_SECONDARY_VNIC_RESPONSE)
-        oracle_ds._network_config = {
-            "version": 2,
-            "ethernets": {"primary": {"nic": {}}},
-        }
-        with mock.patch(
-            f"{DS_PATH}.get_interfaces_by_mac",
-            return_value={
-                "02:00:17:05:d1:db": "ens3",
-                "00:00:17:02:2b:b1": "ens4",
-            },
-        ):
-            oracle_ds._add_network_config_from_opc_imds(
-                set_primary=set_primary
-            )
-
-        nic_cfg = oracle_ds.network_config["ethernets"]
-        if set_primary:
-            assert "ens3" in nic_cfg
-            primary_cfg = nic_cfg["ens3"]
-
-            assert primary_cfg["dhcp4"] is True
-            assert primary_cfg["dhcp6"] is False
-            assert "02:00:17:05:d1:db" == primary_cfg["match"]["macaddress"]
-            assert 9000 == primary_cfg["mtu"]
-            assert "addresses" not in primary_cfg
-
-        assert "ens4" in nic_cfg
-        secondary_cfg = nic_cfg["ens4"]
-        assert secondary_cfg["dhcp4"] is False
-        assert secondary_cfg["dhcp6"] is False
-        assert "00:00:17:02:2b:b1" == secondary_cfg["match"]["macaddress"]
-        assert 9000 == secondary_cfg["mtu"]
-
-        assert 1 == len(secondary_cfg["addresses"])
-        assert "10.0.0.231/24" == secondary_cfg["addresses"][0]
-
     @pytest.mark.parametrize(
         "set_primary",
         [
@@ -578,53 +536,6 @@ def test_imds_nic_setup_v1_ipv6_only(self, set_primary, oracle_ds):
         )
         assert "static" == secondary_cfg["subnets"][0]["type"]
 
-    @pytest.mark.parametrize(
-        "set_primary",
-        [True, False],
-    )
-    def test_secondary_nic_v2_ipv6_only(self, set_primary, oracle_ds):
-        oracle_ds._vnics_data = json.loads(
-            OPC_VM_IPV6_ONLY_SECONDARY_VNIC_RESPONSE
-        )
-        oracle_ds._network_config = {
-            "version": 2,
-            "ethernets": {"primary": {"nic": {}}},
-        }
-        with mock.patch(
-            f"{DS_PATH}.get_interfaces_by_mac",
-            return_value={
-                "02:00:17:0d:6b:be": "ens3",
-                "02:00:17:18:f6:ff": "ens4",
-            },
-        ):
-            oracle_ds._add_network_config_from_opc_imds(
-                set_primary=set_primary
-            )
-
-        nic_cfg = oracle_ds.network_config["ethernets"]
-        if set_primary:
-            assert "ens3" in nic_cfg
-            primary_cfg = nic_cfg["ens3"]
-
-            assert primary_cfg["dhcp4"] is False
-            assert primary_cfg["dhcp6"] is True
-            assert "02:00:17:0d:6b:be" == primary_cfg["match"]["macaddress"]
-            assert 9000 == primary_cfg["mtu"]
-            assert "addresses" not in primary_cfg
-
-        assert "ens4" in nic_cfg
-        secondary_cfg = nic_cfg["ens4"]
-        assert secondary_cfg["dhcp4"] is False
-        assert secondary_cfg["dhcp6"] is False
-        assert "02:00:17:18:f6:ff" == secondary_cfg["match"]["macaddress"]
-        assert 9000 == secondary_cfg["mtu"]
-
-        assert 1 == len(secondary_cfg["addresses"])
-        assert (
-            "2603:c020:400d:5d7e:aacc:8e5f:3b1b:3a4a/128"
-            == secondary_cfg["addresses"][0]
-        )
-
     @pytest.mark.parametrize("error_add_network", [None, Exception])
     @pytest.mark.parametrize(
         "configure_secondary_nics",