Merge ~sw37th/cloud-init:fix_for_opennebula into cloud-init:master

[Akihiko Ota]

OpenNebula: Improve network configuration support.

Network configuration in OpenNebula would only work if the host correctly
guessed the names of the devices in the guest. OpenNebula provided data
in its context.sh like 'ETH0_NETWORK', but if the guest named devices
differently then results were not predictable. This would occur with
Predictable Network Interface Names. To address this,
newer versions (of OpenNebula provide the mac address ETH0_MAC.
This function is present in 4.14 and documented officially in 5.0 docs.

This provides support for reading the mac addresses from the context.sh.
It also fixes cases where context.sh provided a field (ETH0_NETWORK
or ETH0_MASK) with a empty string. Previously the empty string would
be used rather than falling back to the default.

LP: #1719157, #1716397, #1736750

[Scott Moser (smoser)]

Akihko,

Hi, Thanks for your merge proposal and for your patience in sticking with it. I'm sorry you went largely ignored in those bugs.

Over all this looks good and you're clearly fixing things that were broken or unimplemented.

Please feel free to ping me in IRC if you need more immediate feedback.

Some requests:
 a.) can you add some tests? there are tests at tests/unittests/test_datasource/test_opennebula.py
 b.) here is some general cleanups i saw when reviewing. Just reduces some copy-and-paste. http://paste.ubuntu.com/26183949/
 c.) can you find and add information here on what versions of OpenNebula add the mac address fields?

 d.) Do you happen to know if trunk was actually just completely broken for network config generation?
 e.) ultimately i'd like for OpenNebulaNetwork.gen_conf() to return the newer network config rather than returning ENI format and then converting.

 I wont push on 'd' now, but i'd like to have that in the future. I think its probably pretty easy to do, you'll a 'v1' or 'v2' as described in
  http://cloudinit.readthedocs.io/en/latest/topics/network-config-format-v1.html
  http://cloudinit.readthedocs.io/en/latest/topics/network-config-format-v2.html

Also, I'll update your "commit message" here to give squashed description (we squash when we merge).

Thanks again!

review: Needs Fixing

[Scott Moser (smoser)]

http://paste.ubuntu.com/26184053/

^ is an updated paste to support get_mask and get_network having empty strings.

72e6213... by Akihiko Ota on 2017-12-16

OpenNebula: clean up and reduces copy-and-paste

Applied a patch by Scott Moser (smoser).
http://paste.ubuntu.com/26183949/

0abbfc5... by Akihiko Ota on 2017-12-18

tests: add some tests for OpenNebula network interface

[Akihiko Ota (sw37th)]

Scott,

> Some requests:
> a.) can you add some tests? there are tests at
> tests/unittests/test_datasource/test_opennebula.py

I have added some tests. Please reviwe it.

> b.) here is some general cleanups i saw when reviewing. Just reduces some
> copy-and-paste. http://paste.ubuntu.com/26183949/

I applied this patch. Thanks.

> c.) can you find and add information here on what versions of OpenNebula add
> the mac address fields?

The discription of ETHx_MAC field can be found on OpenNebula 5.0 document.
(http://docs.opennebula.org/5.0/operation/references/template.html#context-section)
But it was already implemented at least in OpenNebula 4.14.

> d.) Do you happen to know if trunk was actually just completely broken for
> network config generation?
> e.) ultimately i'd like for OpenNebulaNetwork.gen_conf() to return the newer
> network config rather than returning ENI format and then converting.
>
> I wont push on 'd' now, but i'd like to have that in the future. I think its
> probably pretty easy to do, you'll a 'v1' or 'v2' as described in
> http://cloudinit.readthedocs.io/en/latest/topics/network-config-
> format-v1.html
> http://cloudinit.readthedocs.io/en/latest/topics/network-config-
> format-v2.html

I agree. It's better to modify gen_conf() to use 'v1' or 'v2' configuration.

> Also, I'll update your "commit message" here to give squashed description (we
> squash when we merge).

Thanks!

[Server Team CI bot (server-team-bot)]

FAILED: Continuous integration, rev:
https://jenkins.ubuntu.com/server/job/cloud-init-ci/652/
Executed test runs:
    SUCCESS: Checkout
    SUCCESS: Unit & Style Tests
    SUCCESS: Ubuntu LTS: Build
    SUCCESS: Ubuntu LTS: Integration
    FAILED: MAAS Compatability Testing

Click here to trigger a rebuild:
https://jenkins.ubuntu.com/server/job/cloud-init-ci/652/rebuild

review: Needs Fixing (continuous-integration)

[Scott Moser (smoser)]

Akihiko,

I looked to pull this in, but thought I'd add one more test for multiple nics.
Can you review and then integrate this patch?
  https://paste.ubuntu.com/26227893/

thanks for your patience.
Scott

[Scott Moser (smoser)]

Also, this one *has* to be done, it is why the c-i bot complained.
http://paste.ubuntu.com/26227914/

[Scott Moser (smoser)]

review: Needs Fixing

849b139... by Akihiko Ota on 2017-12-23

merge 238e9da9c4423aed6aeaba8eb77fe747d0d0a071

3cca981... by Akihiko Ota on 2017-12-23

OpenNebula: avoid the c-i bot complaining

Applied a patch by Scott Moser (smoser).
https://code.launchpad.net/~sw37th/cloud-init/+git/cloud-init/+merge/335217/comments/878981

[Akihiko Ota (sw37th)]

Scott,

That's fine! I have merged your patches. Thanks!

Unmerged commits

3cca981... by Akihiko Ota on 2017-12-23

OpenNebula: avoid the c-i bot complaining

Applied a patch by Scott Moser (smoser).
https://code.launchpad.net/~sw37th/cloud-init/+git/cloud-init/+merge/335217/comments/878981

849b139... by Akihiko Ota on 2017-12-23

merge 238e9da9c4423aed6aeaba8eb77fe747d0d0a071

0abbfc5... by Akihiko Ota on 2017-12-18

tests: add some tests for OpenNebula network interface

72e6213... by Akihiko Ota on 2017-12-16

OpenNebula: clean up and reduces copy-and-paste

Applied a patch by Scott Moser (smoser).
http://paste.ubuntu.com/26183949/

73268b9... by Akihiko Ota on 2017-12-14

OpenNebula: add key check for context_devname

be9b67e... by Akihiko Ota on 2017-12-13

OpenNebula: get_mask() and get_network() return empty string

get_mask() and get_network() check keys of CONTEXT Attributes,
but doesn't check its values. If CONTEXT Attribute key ETH0_MASK
and/or ETH0_NETWORK have no value, these methods should return
default values, however actually return empty string('').

This patch adds value checks to these methods.

LP: #1736750

b022c4c... by Akihiko Ota on 2017-12-13

OpenNebula: Support for Predictable Network Interface Names

OpenNebula assumes network interface names as eth[0-9] and uses
them as variable name in context.sh, but newer distros uses
Predictable Interface Names.

This patch maps Predictable Interface Names and context.sh's
variable names by mac address.

LP: #1716397

eae1424... by Akihiko Ota on 2017-12-13

OpenNebula: add network_config property

DataSourceOpenNebula has no network_config property, so it cannot
return network configurations.

This patch adds network_config property to DataSourceOpenNebula.

LP: #1719157

diff --git a/cloudinit/net/__init__.py b/cloudinit/net/__init__.py
index a1b0db1..c015e79 100644
--- a/cloudinit/net/__init__.py
+++ b/cloudinit/net/__init__.py
@@ -18,7 +18,7 @@ SYS_CLASS_NET = "/sys/class/net/"
 DEFAULT_PRIMARY_INTERFACE = 'eth0'
 
 
-def _natural_sort_key(s, _nsre=re.compile('([0-9]+)')):
+def natural_sort_key(s, _nsre=re.compile('([0-9]+)')):
     """Sorting for Humans: natural sort order. Can be use as the key to sort
     functions.
     This will sort ['eth0', 'ens3', 'ens10', 'ens12', 'ens8', 'ens0'] as
@@ -224,7 +224,7 @@ def find_fallback_nic(blacklist_drivers=None):
 
     # if eth0 exists use it above anything else, otherwise get the interface
     # that we can read 'first' (using the sorted defintion of first).
-    names = list(sorted(potential_interfaces, key=_natural_sort_key))
+    names = list(sorted(potential_interfaces, key=natural_sort_key))
     if DEFAULT_PRIMARY_INTERFACE in names:
         names.remove(DEFAULT_PRIMARY_INTERFACE)
         names.insert(0, DEFAULT_PRIMARY_INTERFACE)
diff --git a/cloudinit/sources/DataSourceOpenNebula.py b/cloudinit/sources/DataSourceOpenNebula.py
index f66c95d..ce47b6b 100644
--- a/cloudinit/sources/DataSourceOpenNebula.py
+++ b/cloudinit/sources/DataSourceOpenNebula.py
@@ -12,6 +12,7 @@
 #
 # This file is part of cloud-init. See LICENSE file for license information.
 
+import collections
 import os
 import pwd
 import re
@@ -19,6 +20,7 @@ import string
 
 from cloudinit import log as logging
 from cloudinit import net
+from cloudinit.net import eni
 from cloudinit import sources
 from cloudinit import util
 
@@ -89,11 +91,18 @@ class DataSourceOpenNebula(sources.DataSource):
             return False
 
         self.seed = seed
-        self.network_eni = results.get("network_config")
+        self.network_eni = results.get('network-interfaces')
         self.metadata = md
         self.userdata_raw = results.get('userdata')
         return True
 
+    @property
+    def network_config(self):
+        if self.network_eni is not None:
+            return eni.convert_eni_data(self.network_eni)
+        else:
+            return None
+
     def get_hostname(self, fqdn=False, resolve_ip=None):
         if resolve_ip is None:
             if self.dsmode == sources.DSMODE_NETWORK:
@@ -116,58 +125,53 @@ class OpenNebulaNetwork(object):
         self.context = context
         if system_nics_by_mac is None:
             system_nics_by_mac = get_physical_nics_by_mac()
-        self.ifaces = system_nics_by_mac
+        self.ifaces = collections.OrderedDict(
+            [k for k in sorted(system_nics_by_mac.items(),
+                               key=lambda k: net.natural_sort_key(k[1]))])
+
+        # OpenNebula 4.14+ provide macaddr for ETHX in variable ETH_MAC.
+        # context_devname provides {mac.lower():ETHX, mac2.lower():ETHX}
+        self.context_devname = {}
+        for k, v in context.items():
+            m = re.match(r'^(.+)_MAC$', k)
+            if m:
+                self.context_devname[v.lower()] = m.group(1)
 
     def mac2ip(self, mac):
-        components = mac.split(':')[2:]
-        return [str(int(c, 16)) for c in components]
+        return '.'.join([str(int(c, 16)) for c in mac.split(':')[2:]])
 
-    def get_ip(self, dev, components):
-        var_name = dev.upper() + '_IP'
-        if var_name in self.context:
-            return self.context[var_name]
-        else:
-            return '.'.join(components)
+    def mac2network(self, mac):
+        return self.mac2ip(mac).rpartition(".")[0] + ".0"
 
-    def get_mask(self, dev):
-        var_name = dev.upper() + '_MASK'
-        if var_name in self.context:
-            return self.context[var_name]
-        else:
-            return '255.255.255.0'
+    def get_dns(self, dev):
+        return self.get_field(dev, "dns", "").split()
 
-    def get_network(self, dev, components):
-        var_name = dev.upper() + '_NETWORK'
-        if var_name in self.context:
-            return self.context[var_name]
-        else:
-            return '.'.join(components[:-1]) + '.0'
+    def get_domain(self, dev):
+        return self.get_field(dev, "domain")
+
+    def get_ip(self, dev, mac):
+        return self.get_field(dev, "ip", self.mac2ip(mac))
 
     def get_gateway(self, dev):
-        var_name = dev.upper() + '_GATEWAY'
-        if var_name in self.context:
-            return self.context[var_name]
-        else:
-            return None
+        return self.get_field(dev, "gateway")
 
-    def get_dns(self, dev):
-        var_name = dev.upper() + '_DNS'
-        if var_name in self.context:
-            return self.context[var_name]
-        else:
-            return None
+    def get_mask(self, dev):
+        return self.get_field(dev, "mask", "255.255.255.0")
 
-    def get_domain(self, dev):
-        var_name = dev.upper() + '_DOMAIN'
-        if var_name in self.context:
-            return self.context[var_name]
-        else:
-            return None
+    def get_network(self, dev, mac):
+        return self.get_field(dev, "network", self.mac2network(mac))
+
+    def get_field(self, dev, name, default=None):
+        """return the field name in context for device dev.
+
+        context stores <dev>_<NAME> (example: eth0_DOMAIN).
+        an empty string for value will return default."""
+        val = self.context.get('_'.join((dev, name,)).upper())
+        # allow empty string to return the default.
+        return default if val in (None, "") else val
 
     def gen_conf(self):
-        global_dns = []
-        if 'DNS' in self.context:
-            global_dns.append(self.context['DNS'])
+        global_dns = self.context.get('DNS', "").split()
 
         conf = []
         conf.append('auto lo')
@@ -175,29 +179,31 @@ class OpenNebulaNetwork(object):
         conf.append('')
 
         for mac, dev in self.ifaces.items():
-            ip_components = self.mac2ip(mac)
+            mac = mac.lower()
+
+            # c_dev stores name in context 'ETHX' for this device.
+            # dev stores the current system name.
+            c_dev = self.context_devname.get(mac, dev)
 
             conf.append('auto ' + dev)
             conf.append('iface ' + dev + ' inet static')
-            conf.append('  address ' + self.get_ip(dev, ip_components))
-            conf.append('  network ' + self.get_network(dev, ip_components))
-            conf.append('  netmask ' + self.get_mask(dev))
+            conf.append('  #hwaddress %s' % mac)
+            conf.append('  address ' + self.get_ip(c_dev, mac))
+            conf.append('  network ' + self.get_network(c_dev, mac))
+            conf.append('  netmask ' + self.get_mask(c_dev))
 
-            gateway = self.get_gateway(dev)
+            gateway = self.get_gateway(c_dev)
             if gateway:
                 conf.append('  gateway ' + gateway)
 
-            domain = self.get_domain(dev)
+            domain = self.get_domain(c_dev)
             if domain:
                 conf.append('  dns-search ' + domain)
 
             # add global DNS servers to all interfaces
-            dns = self.get_dns(dev)
+            dns = self.get_dns(c_dev)
             if global_dns or dns:
-                all_dns = global_dns
-                if dns:
-                    all_dns.append(dns)
-                conf.append('  dns-nameservers ' + ' '.join(all_dns))
+                conf.append('  dns-nameservers ' + ' '.join(global_dns + dns))
 
             conf.append('')
 
diff --git a/tests/unittests/test_datasource/test_opennebula.py b/tests/unittests/test_datasource/test_opennebula.py
index 2326dd5..5c3ba01 100644
--- a/tests/unittests/test_datasource/test_opennebula.py
+++ b/tests/unittests/test_datasource/test_opennebula.py
@@ -4,6 +4,7 @@ from cloudinit import helpers
 from cloudinit.sources import DataSourceOpenNebula as ds
 from cloudinit import util
 from cloudinit.tests.helpers import mock, populate_dir, CiTestCase
+from textwrap import dedent
 
 import os
 import pwd
@@ -30,6 +31,8 @@ USER_DATA = '#cloud-config\napt_upgrade: true'
 SSH_KEY = 'ssh-rsa AAAAB3NzaC1....sIkJhq8wdX+4I3A4cYbYP ubuntu@server-460-%i'
 HOSTNAME = 'foo.example.com'
 PUBLIC_IP = '10.0.0.3'
+MACADDR = '02:00:0a:12:01:01'
+IP_BY_MACADDR = '10.18.1.1'
 
 DS_PATH = "cloudinit.sources.DataSourceOpenNebula"
 
@@ -195,24 +198,96 @@ class TestOpenNebulaDataSource(CiTestCase):
 
     @mock.patch(DS_PATH + ".get_physical_nics_by_mac")
     def test_hostname(self, m_get_phys_by_mac):
-        m_get_phys_by_mac.return_value = {'02:00:0a:12:01:01': 'eth0'}
-        for k in ('HOSTNAME', 'PUBLIC_IP', 'IP_PUBLIC', 'ETH0_IP'):
-            my_d = os.path.join(self.tmp, k)
-            populate_context_dir(my_d, {k: PUBLIC_IP})
-            results = ds.read_context_disk_dir(my_d)
+        for dev in ('eth0', 'ens3'):
+            m_get_phys_by_mac.return_value = {MACADDR: dev}
+            for k in ('HOSTNAME', 'PUBLIC_IP', 'IP_PUBLIC', 'ETH0_IP'):
+                my_d = os.path.join(self.tmp, k)
+                populate_context_dir(my_d, {k: PUBLIC_IP})
+                results = ds.read_context_disk_dir(my_d)
 
-            self.assertTrue('metadata' in results)
-            self.assertTrue('local-hostname' in results['metadata'])
-            self.assertEqual(PUBLIC_IP, results['metadata']['local-hostname'])
+                self.assertTrue('metadata' in results)
+                self.assertTrue('local-hostname' in results['metadata'])
+                self.assertEqual(
+                    PUBLIC_IP, results['metadata']['local-hostname'])
 
     @mock.patch(DS_PATH + ".get_physical_nics_by_mac")
     def test_network_interfaces(self, m_get_phys_by_mac):
-        m_get_phys_by_mac.return_value = {'02:00:0a:12:01:01': 'eth0'}
-        populate_context_dir(self.seed_dir, {'ETH0_IP': '1.2.3.4'})
-        results = ds.read_context_disk_dir(self.seed_dir)
-
-        self.assertTrue('network-interfaces' in results)
-        self.assertTrue('1.2.3.4' in results['network-interfaces'])
+        for dev in ('eth0', 'ens3'):
+            m_get_phys_by_mac.return_value = {MACADDR: dev}
+
+            # without ETH0_MAC
+            # for Older OpenNebula?
+            populate_context_dir(self.seed_dir, {'ETH0_IP': IP_BY_MACADDR})
+            results = ds.read_context_disk_dir(self.seed_dir)
+
+            self.assertTrue('network-interfaces' in results)
+            self.assertTrue(IP_BY_MACADDR in results['network-interfaces'])
+
+            # ETH0_IP and ETH0_MAC
+            populate_context_dir(
+                self.seed_dir, {'ETH0_IP': IP_BY_MACADDR, 'ETH0_MAC': MACADDR})
+            results = ds.read_context_disk_dir(self.seed_dir)
+
+            self.assertTrue('network-interfaces' in results)
+            self.assertTrue(IP_BY_MACADDR in results['network-interfaces'])
+
+            # ETH0_IP with empty string and ETH0_MAC
+            # in the case of using Virtual Network contains
+            # "AR = [ TYPE = ETHER ]"
+            populate_context_dir(
+                self.seed_dir, {'ETH0_IP': '', 'ETH0_MAC': MACADDR})
+            results = ds.read_context_disk_dir(self.seed_dir)
+
+            self.assertTrue('network-interfaces' in results)
+            self.assertTrue(IP_BY_MACADDR in results['network-interfaces'])
+
+            # ETH0_NETWORK
+            populate_context_dir(
+                self.seed_dir, {
+                    'ETH0_IP': IP_BY_MACADDR,
+                    'ETH0_MAC': MACADDR,
+                    'ETH0_NETWORK': '10.18.0.0'
+                })
+            results = ds.read_context_disk_dir(self.seed_dir)
+
+            self.assertTrue('network-interfaces' in results)
+            self.assertTrue('10.18.0.0' in results['network-interfaces'])
+
+            # ETH0_NETWORK with empty string
+            populate_context_dir(
+                self.seed_dir, {
+                    'ETH0_IP': IP_BY_MACADDR,
+                    'ETH0_MAC': MACADDR,
+                    'ETH0_NETWORK': ''
+                })
+            results = ds.read_context_disk_dir(self.seed_dir)
+
+            self.assertTrue('network-interfaces' in results)
+            self.assertTrue('10.18.1.0' in results['network-interfaces'])
+
+            # ETH0_MASK
+            populate_context_dir(
+                self.seed_dir, {
+                    'ETH0_IP': IP_BY_MACADDR,
+                    'ETH0_MAC': MACADDR,
+                    'ETH0_MASK': '255.255.0.0'
+                })
+            results = ds.read_context_disk_dir(self.seed_dir)
+
+            self.assertTrue('network-interfaces' in results)
+            self.assertTrue('255.255.0.0' in results['network-interfaces'])
+
+            # ETH0_MASK with empty string
+            populate_context_dir(
+                self.seed_dir, {
+                    'ETH0_IP': IP_BY_MACADDR,
+                    'ETH0_MAC': MACADDR,
+                    'ETH0_MASK': ''
+                })
+            results = ds.read_context_disk_dir(self.seed_dir)
+
+            self.assertTrue('network-interfaces' in results)
+            self.assertTrue('255.255.255.0' in results['network-interfaces'])
 
     def test_find_candidates(self):
         def my_devs_with(criteria):
@@ -233,7 +308,7 @@ class TestOpenNebulaDataSource(CiTestCase):
 
 class TestOpenNebulaNetwork(unittest.TestCase):
 
-    system_nics = {'02:00:0a:12:01:01': 'eth0'}
+    system_nics = ('eth0', 'ens3')
 
     def test_lo(self):
         net = ds.OpenNebulaNetwork(context={}, system_nics_by_mac={})
@@ -244,45 +319,101 @@ iface lo inet loopback
 
     @mock.patch(DS_PATH + ".get_physical_nics_by_mac")
     def test_eth0(self, m_get_phys_by_mac):
-        m_get_phys_by_mac.return_value = self.system_nics
-        net = ds.OpenNebulaNetwork({})
-        self.assertEqual(net.gen_conf(), u'''\
-auto lo
-iface lo inet loopback
-
-auto eth0
-iface eth0 inet static
-  address 10.18.1.1
-  network 10.18.1.0
-  netmask 255.255.255.0
-''')
+        for nic in self.system_nics:
+            m_get_phys_by_mac.return_value = {MACADDR: nic}
+            net = ds.OpenNebulaNetwork({})
+            self.assertEqual(net.gen_conf(), dedent("""\
+                auto lo
+                iface lo inet loopback
+
+                auto {dev}
+                iface {dev} inet static
+                  #hwaddress {macaddr}
+                  address 10.18.1.1
+                  network 10.18.1.0
+                  netmask 255.255.255.0
+                """.format(dev=nic, macaddr=MACADDR)))
 
     def test_eth0_override(self):
         context = {
             'DNS': '1.2.3.8',
-            'ETH0_IP': '1.2.3.4',
-            'ETH0_NETWORK': '1.2.3.0',
+            'ETH0_IP': '10.18.1.1',
+            'ETH0_NETWORK': '10.18.0.0',
             'ETH0_MASK': '255.255.0.0',
             'ETH0_GATEWAY': '1.2.3.5',
             'ETH0_DOMAIN': 'example.com',
-            'ETH0_DNS': '1.2.3.6 1.2.3.7'
+            'ETH0_DNS': '1.2.3.6 1.2.3.7',
+            'ETH0_MAC': '02:00:0a:12:01:01'
         }
-
-        net = ds.OpenNebulaNetwork(context,
-                                   system_nics_by_mac=self.system_nics)
-        self.assertEqual(net.gen_conf(), u'''\
-auto lo
-iface lo inet loopback
-
-auto eth0
-iface eth0 inet static
-  address 1.2.3.4
-  network 1.2.3.0
-  netmask 255.255.0.0
-  gateway 1.2.3.5
-  dns-search example.com
-  dns-nameservers 1.2.3.8 1.2.3.6 1.2.3.7
-''')
+        for nic in self.system_nics:
+            expected = dedent("""\
+                auto lo
+                iface lo inet loopback
+
+                auto {dev}
+                iface {dev} inet static
+                  #hwaddress {macaddr}
+                  address 10.18.1.1
+                  network 10.18.0.0
+                  netmask 255.255.0.0
+                  gateway 1.2.3.5
+                  dns-search example.com
+                  dns-nameservers 1.2.3.8 1.2.3.6 1.2.3.7
+                  """).format(dev=nic, macaddr=MACADDR)
+            net = ds.OpenNebulaNetwork(context,
+                                       system_nics_by_mac={MACADDR: nic})
+            self.assertEqual(expected, net.gen_conf())
+
+    def test_multiple_nics(self):
+        """Test rendering multiple nics with names that differ from context."""
+        MAC_1 = "02:00:0a:12:01:01"
+        MAC_2 = "02:00:0a:12:01:02"
+        context = {
+            'DNS': '1.2.3.8',
+            'ETH0_IP': '10.18.1.1',
+            'ETH0_NETWORK': '10.18.0.0',
+            'ETH0_MASK': '255.255.0.0',
+            'ETH0_GATEWAY': '1.2.3.5',
+            'ETH0_DOMAIN': 'example.com',
+            'ETH0_DNS': '1.2.3.6 1.2.3.7',
+            'ETH0_MAC': MAC_2,
+            'ETH3_IP': '10.3.1.3',
+            'ETH3_NETWORK': '10.3.0.0',
+            'ETH3_MASK': '255.255.0.0',
+            'ETH3_GATEWAY': '10.3.0.1',
+            'ETH3_DOMAIN': 'third.example.com',
+            'ETH3_DNS': '10.3.1.2',
+            'ETH3_MAC': MAC_1,
+        }
+        net = ds.OpenNebulaNetwork(
+            context, system_nics_by_mac={MAC_1: 'enp0s25', MAC_2: 'enp1s2'})
+
+        expected = dedent("""\
+            auto lo
+            iface lo inet loopback
+
+            auto enp0s25
+            iface enp0s25 inet static
+              #hwaddress 02:00:0a:12:01:01
+              address 10.3.1.3
+              network 10.3.0.0
+              netmask 255.255.0.0
+              gateway 10.3.0.1
+              dns-search third.example.com
+              dns-nameservers 1.2.3.8 10.3.1.2
+
+            auto enp1s2
+            iface enp1s2 inet static
+              #hwaddress 02:00:0a:12:01:02
+              address 10.18.1.1
+              network 10.18.0.0
+              netmask 255.255.0.0
+              gateway 1.2.3.5
+              dns-search example.com
+              dns-nameservers 1.2.3.8 1.2.3.6 1.2.3.7
+            """)
+
+        self.assertEqual(expected, net.gen_conf())
 
 
 class TestParseShellConfig(unittest.TestCase):
diff --git a/tests/unittests/test_net.py b/tests/unittests/test_net.py
index f3fa2a3..ddea13d 100644
--- a/tests/unittests/test_net.py
+++ b/tests/unittests/test_net.py
@@ -1,9 +1,9 @@
 # This file is part of cloud-init. See LICENSE file for license information.
 
 from cloudinit import net
-from cloudinit.net import _natural_sort_key
 from cloudinit.net import cmdline
 from cloudinit.net import eni
+from cloudinit.net import natural_sort_key
 from cloudinit.net import netplan
 from cloudinit.net import network_state
 from cloudinit.net import renderers
@@ -2708,11 +2708,11 @@ class TestInterfacesSorting(CiTestCase):
     def test_natural_order(self):
         data = ['ens5', 'ens6', 'ens3', 'ens20', 'ens13', 'ens2']
         self.assertEqual(
-            sorted(data, key=_natural_sort_key),
+            sorted(data, key=natural_sort_key),
             ['ens2', 'ens3', 'ens5', 'ens6', 'ens13', 'ens20'])
         data2 = ['enp2s0', 'enp2s3', 'enp0s3', 'enp0s13', 'enp0s8', 'enp1s2']
         self.assertEqual(
-            sorted(data2, key=_natural_sort_key),
+            sorted(data2, key=natural_sort_key),
             ['enp0s3', 'enp0s8', 'enp0s13', 'enp1s2', 'enp2s0', 'enp2s3'])