Merge ~raharper/cloud-init:fix/ephemeral-dhcp-static-routes into cloud-init:master

[Ryan Harper]

net: add rfc3442 (classless static routes) to EphemeralDHCP

The EphemeralDHCP context manager did not parse or handle
rfc3442 classless static routes which prevented reading
datasource metadata in some clouds. This branch adds support
for extracting the field from the leases output, parsing the
format and then adding the required iproute2 ip commands to
apply (and teardown) the static routes.

LP: #1821102

[Dan Watkins (oddbloke)]

Wow, what an annoying format to have to parse. Overall, I think this looks good; I have a couple of inline comments. I'd also like to see us expand the unit testing of the parsing code so that we're at least covering every branch in there (and ideally doing at least one test with a bunch combined, to make sure that our skip lengths are accurate).

review: Needs Fixing

[Ryan Harper (raharper)]

+1 on expanded testing of the rfc3442 parsing.

20187bf... by Ryan Harper on 2019-06-07

address feedback on parsing rfc3442

dhcp.py/parse_static_routes:
 - Fix comments to match code and correct values
 - Always return a list type
 - Reduce parsing of the result but returning a list of tuples
   containing the network address and the gateway.
 - fix unittests

7ff9772... by Ryan Harper on 2019-06-13

RFC3442: add additional unittests and error logging

Adding additional unittests for parsing of RFC3442 format.
  - Fix missing net_length for class a, b, c routes
  - Removed hard-coded net_length for default routes
  - Log an error with details on what failed during parsing

b5a4708... by Ryan Harper on 2019-06-13

rfc3442: update docstring to indicate inclusion of net length

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

FAILED: Continuous integration, rev:b5a47081cfd934b5a1789b84ff506b2d0ca1a03e
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review: Needs Fixing (continuous-integration)

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

FAILED: Continuous integration, rev:b5a47081cfd934b5a1789b84ff506b2d0ca1a03e
https://jenkins.ubuntu.com/server/job/cloud-init-ci/737/
Executed test runs:
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    SUCCESS: Unit & Style Tests
    FAILED: Ubuntu LTS: Build

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review: Needs Fixing (continuous-integration)

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

FAILED: Continuous integration, rev:b5a47081cfd934b5a1789b84ff506b2d0ca1a03e
https://jenkins.ubuntu.com/server/job/cloud-init-ci/739/
Executed test runs:
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review: Needs Fixing (continuous-integration)

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

PASSED: Continuous integration, rev:b5a47081cfd934b5a1789b84ff506b2d0ca1a03e
https://jenkins.ubuntu.com/server/job/cloud-init-ci/740/
Executed test runs:
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    SUCCESS: Unit & Style Tests
    SUCCESS: Ubuntu LTS: Build
    SUCCESS: Ubuntu LTS: Integration
    IN_PROGRESS: Declarative: Post Actions

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review: Approve (continuous-integration)

[Dan Watkins (oddbloke)]

Incomplete review at EOD.

[Scott Moser (smoser)]

You've done a good job here. I didn't read the implementation completely, but the tests are good.

[Ryan Harper (raharper)]

Thanks, I'll update

3a9ec1a... by Ryan Harper on 2019-07-11

Log and error if netlength is invalid

[Ryan Harper (raharper)]

@Scott,

I left the comment where it is so to explain when cloud-init will take one path or the other.

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

FAILED: Continuous integration, rev:3a9ec1a0ef6cb3452f7b1bb8b70c5c8275971932
https://jenkins.ubuntu.com/server/job/cloud-init-ci/773/
Executed test runs:
    SUCCESS: Checkout
    SUCCESS: Unit & Style Tests
    FAILED: Ubuntu LTS: Build

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review: Needs Fixing (continuous-integration)

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

PASSED: Continuous integration, rev:3a9ec1a0ef6cb3452f7b1bb8b70c5c8275971932
https://jenkins.ubuntu.com/server/job/cloud-init-ci/774/
Executed test runs:
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    SUCCESS: Unit & Style Tests
    SUCCESS: Ubuntu LTS: Build
    SUCCESS: Ubuntu LTS: Integration
    IN_PROGRESS: Declarative: Post Actions

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review: Approve (continuous-integration)

[Dan Watkins (oddbloke)]

Looking really good overall; a couple more inline questions, but this is v. close.

[Ryan Harper (raharper)]

Thanks, I've replied inline, looking for your thoughts before I refactor.

24e1632... by Ryan Harper on 2019-07-16

parse_static_routes: on parsing error return parsed static routes like dhclient

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

PASSED: Continuous integration, rev:24e1632715344f3cdb615f153e2fae30dce0f4bc
https://jenkins.ubuntu.com/server/job/cloud-init-ci/789/
Executed test runs:
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    SUCCESS: Unit & Style Tests
    SUCCESS: Ubuntu LTS: Build
    SUCCESS: Ubuntu LTS: Integration
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review: Approve (continuous-integration)

[Dan Watkins (oddbloke)]

Thanks for working through all this, Ryan, looks good to me!

review: Approve

diff --git a/cloudinit/net/__init__.py b/cloudinit/net/__init__.py
index e758006..624c9b4 100644
--- a/cloudinit/net/__init__.py
+++ b/cloudinit/net/__init__.py
@@ -679,7 +679,7 @@ class EphemeralIPv4Network(object):
     """
 
     def __init__(self, interface, ip, prefix_or_mask, broadcast, router=None,
-                 connectivity_url=None):
+                 connectivity_url=None, static_routes=None):
         """Setup context manager and validate call signature.
 
         @param interface: Name of the network interface to bring up.
@@ -690,6 +690,7 @@ class EphemeralIPv4Network(object):
         @param router: Optionally the default gateway IP.
         @param connectivity_url: Optionally, a URL to verify if a usable
            connection already exists.
+        @param static_routes: Optionally a list of static routes from DHCP
         """
         if not all([interface, ip, prefix_or_mask, broadcast]):
             raise ValueError(
@@ -706,6 +707,7 @@ class EphemeralIPv4Network(object):
         self.ip = ip
         self.broadcast = broadcast
         self.router = router
+        self.static_routes = static_routes
         self.cleanup_cmds = []  # List of commands to run to cleanup state.
 
     def __enter__(self):
@@ -718,7 +720,21 @@ class EphemeralIPv4Network(object):
                 return
 
         self._bringup_device()
-        if self.router:
+
+        # rfc3442 requires us to ignore the router config *if* classless static
+        # routes are provided.
+        #
+        # https://tools.ietf.org/html/rfc3442
+        #
+        # If the DHCP server returns both a Classless Static Routes option and
+        # a Router option, the DHCP client MUST ignore the Router option.
+        #
+        # Similarly, if the DHCP server returns both a Classless Static Routes
+        # option and a Static Routes option, the DHCP client MUST ignore the
+        # Static Routes option.
+        if self.static_routes:
+            self._bringup_static_routes()
+        elif self.router:
             self._bringup_router()
 
     def __exit__(self, excp_type, excp_value, excp_traceback):
@@ -762,6 +778,20 @@ class EphemeralIPv4Network(object):
                 ['ip', '-family', 'inet', 'addr', 'del', cidr, 'dev',
                  self.interface])
 
+    def _bringup_static_routes(self):
+        # static_routes = [("169.254.169.254/32", "130.56.248.255"),
+        #                  ("0.0.0.0/0", "130.56.240.1")]
+        for net_address, gateway in self.static_routes:
+            via_arg = []
+            if gateway != "0.0.0.0/0":
+                via_arg = ['via', gateway]
+            util.subp(
+                ['ip', '-4', 'route', 'add', net_address] + via_arg +
+                ['dev', self.interface], capture=True)
+            self.cleanup_cmds.insert(
+                0, ['ip', '-4', 'route', 'del', net_address] + via_arg +
+                   ['dev', self.interface])
+
     def _bringup_router(self):
         """Perform the ip commands to fully setup the router if needed."""
         # Check if a default route exists and exit if it does
diff --git a/cloudinit/net/dhcp.py b/cloudinit/net/dhcp.py
index c98a97c..1737991 100644
--- a/cloudinit/net/dhcp.py
+++ b/cloudinit/net/dhcp.py
@@ -92,10 +92,14 @@ class EphemeralDHCPv4(object):
         nmap = {'interface': 'interface', 'ip': 'fixed-address',
                 'prefix_or_mask': 'subnet-mask',
                 'broadcast': 'broadcast-address',
+                'static_routes': 'rfc3442-classless-static-routes',
                 'router': 'routers'}
         kwargs = dict([(k, self.lease.get(v)) for k, v in nmap.items()])
         if not kwargs['broadcast']:
             kwargs['broadcast'] = bcip(kwargs['prefix_or_mask'], kwargs['ip'])
+        if kwargs['static_routes']:
+            kwargs['static_routes'] = (
+                parse_static_routes(kwargs['static_routes']))
         if self.connectivity_url:
             kwargs['connectivity_url'] = self.connectivity_url
         ephipv4 = EphemeralIPv4Network(**kwargs)
@@ -272,4 +276,90 @@ def networkd_get_option_from_leases(keyname, leases_d=None):
             return data[keyname]
     return None
 
+
+def parse_static_routes(rfc3442):
+    """ parse rfc3442 format and return a list containing tuple of strings.
+
+    The tuple is composed of the network_address (including net length) and
+    gateway for a parsed static route.
+
+    @param rfc3442: string in rfc3442 format
+    @returns: list of tuple(str, str) for all valid parsed routes until the
+              first parsing error.
+
+    E.g.
+    sr = parse_state_routes("32,169,254,169,254,130,56,248,255,0,130,56,240,1")
+    sr = [
+        ("169.254.169.254/32", "130.56.248.255"), ("0.0.0.0/0", "130.56.240.1")
+    ]
+
+    Python version of isc-dhclient's hooks:
+       /etc/dhcp/dhclient-exit-hooks.d/rfc3442-classless-routes
+    """
+    # raw strings from dhcp lease may end in semi-colon
+    rfc3442 = rfc3442.rstrip(";")
+    tokens = rfc3442.split(',')
+    static_routes = []
+
+    def _trunc_error(cidr, required, remain):
+        msg = ("RFC3442 string malformed.  Current route has CIDR of %s "
+               "and requires %s significant octets, but only %s remain. "
+               "Verify DHCP rfc3442-classless-static-routes value: %s"
+               % (cidr, required, remain, rfc3442))
+        LOG.error(msg)
+
+    current_idx = 0
+    for idx, tok in enumerate(tokens):
+        if idx < current_idx:
+            continue
+        net_length = int(tok)
+        if net_length in range(25, 33):
+            req_toks = 9
+            if len(tokens[idx:]) < req_toks:
+                _trunc_error(net_length, req_toks, len(tokens[idx:]))
+                return static_routes
+            net_address = ".".join(tokens[idx+1:idx+5])
+            gateway = ".".join(tokens[idx+5:idx+req_toks])
+            current_idx = idx + req_toks
+        elif net_length in range(17, 25):
+            req_toks = 8
+            if len(tokens[idx:]) < req_toks:
+                _trunc_error(net_length, req_toks, len(tokens[idx:]))
+                return static_routes
+            net_address = ".".join(tokens[idx+1:idx+4] + ["0"])
+            gateway = ".".join(tokens[idx+4:idx+req_toks])
+            current_idx = idx + req_toks
+        elif net_length in range(9, 17):
+            req_toks = 7
+            if len(tokens[idx:]) < req_toks:
+                _trunc_error(net_length, req_toks, len(tokens[idx:]))
+                return static_routes
+            net_address = ".".join(tokens[idx+1:idx+3] + ["0", "0"])
+            gateway = ".".join(tokens[idx+3:idx+req_toks])
+            current_idx = idx + req_toks
+        elif net_length in range(1, 9):
+            req_toks = 6
+            if len(tokens[idx:]) < req_toks:
+                _trunc_error(net_length, req_toks, len(tokens[idx:]))
+                return static_routes
+            net_address = ".".join(tokens[idx+1:idx+2] + ["0", "0", "0"])
+            gateway = ".".join(tokens[idx+2:idx+req_toks])
+            current_idx = idx + req_toks
+        elif net_length == 0:
+            req_toks = 5
+            if len(tokens[idx:]) < req_toks:
+                _trunc_error(net_length, req_toks, len(tokens[idx:]))
+                return static_routes
+            net_address = "0.0.0.0"
+            gateway = ".".join(tokens[idx+1:idx+req_toks])
+            current_idx = idx + req_toks
+        else:
+            LOG.error('Parsed invalid net length "%s".  Verify DHCP '
+                      'rfc3442-classless-static-routes value.', net_length)
+            return static_routes
+
+        static_routes.append(("%s/%s" % (net_address, net_length), gateway))
+
+    return static_routes
+
 # vi: ts=4 expandtab
diff --git a/cloudinit/net/tests/test_dhcp.py b/cloudinit/net/tests/test_dhcp.py
index 5139024..91f503c 100644
--- a/cloudinit/net/tests/test_dhcp.py
+++ b/cloudinit/net/tests/test_dhcp.py
@@ -8,7 +8,8 @@ from textwrap import dedent
 import cloudinit.net as net
 from cloudinit.net.dhcp import (
     InvalidDHCPLeaseFileError, maybe_perform_dhcp_discovery,
-    parse_dhcp_lease_file, dhcp_discovery, networkd_load_leases)
+    parse_dhcp_lease_file, dhcp_discovery, networkd_load_leases,
+    parse_static_routes)
 from cloudinit.util import ensure_file, write_file
 from cloudinit.tests.helpers import (
     CiTestCase, HttprettyTestCase, mock, populate_dir, wrap_and_call)
@@ -64,6 +65,123 @@ class TestParseDHCPLeasesFile(CiTestCase):
         self.assertItemsEqual(expected, parse_dhcp_lease_file(lease_file))
 
 
+class TestDHCPRFC3442(CiTestCase):
+
+    def test_parse_lease_finds_rfc3442_classless_static_routes(self):
+        """parse_dhcp_lease_file returns rfc3442-classless-static-routes."""
+        lease_file = self.tmp_path('leases')
+        content = dedent("""
+            lease {
+              interface "wlp3s0";
+              fixed-address 192.168.2.74;
+              option subnet-mask 255.255.255.0;
+              option routers 192.168.2.1;
+              option rfc3442-classless-static-routes 0,130,56,240,1;
+              renew 4 2017/07/27 18:02:30;
+              expire 5 2017/07/28 07:08:15;
+            }
+        """)
+        expected = [
+            {'interface': 'wlp3s0', 'fixed-address': '192.168.2.74',
+             'subnet-mask': '255.255.255.0', 'routers': '192.168.2.1',
+             'rfc3442-classless-static-routes': '0,130,56,240,1',
+             'renew': '4 2017/07/27 18:02:30',
+             'expire': '5 2017/07/28 07:08:15'}]
+        write_file(lease_file, content)
+        self.assertItemsEqual(expected, parse_dhcp_lease_file(lease_file))
+
+    @mock.patch('cloudinit.net.dhcp.EphemeralIPv4Network')
+    @mock.patch('cloudinit.net.dhcp.maybe_perform_dhcp_discovery')
+    def test_obtain_lease_parses_static_routes(self, m_maybe, m_ipv4):
+        """EphemeralDHPCv4 parses rfc3442 routes for EphemeralIPv4Network"""
+        lease = [
+            {'interface': 'wlp3s0', 'fixed-address': '192.168.2.74',
+             'subnet-mask': '255.255.255.0', 'routers': '192.168.2.1',
+             'rfc3442-classless-static-routes': '0,130,56,240,1',
+             'renew': '4 2017/07/27 18:02:30',
+             'expire': '5 2017/07/28 07:08:15'}]
+        m_maybe.return_value = lease
+        eph = net.dhcp.EphemeralDHCPv4()
+        eph.obtain_lease()
+        expected_kwargs = {
+            'interface': 'wlp3s0',
+            'ip': '192.168.2.74',
+            'prefix_or_mask': '255.255.255.0',
+            'broadcast': '192.168.2.255',
+            'static_routes': [('0.0.0.0/0', '130.56.240.1')],
+            'router': '192.168.2.1'}
+        m_ipv4.assert_called_with(**expected_kwargs)
+
+
+class TestDHCPParseStaticRoutes(CiTestCase):
+
+    with_logs = True
+
+    def parse_static_routes_empty_string(self):
+        self.assertEqual([], parse_static_routes(""))
+
+    def test_parse_static_routes_invalid_input_returns_empty_list(self):
+        rfc3442 = "32,169,254,169,254,130,56,248"
+        self.assertEqual([], parse_static_routes(rfc3442))
+
+    def test_parse_static_routes_bogus_width_returns_empty_list(self):
+        rfc3442 = "33,169,254,169,254,130,56,248"
+        self.assertEqual([], parse_static_routes(rfc3442))
+
+    def test_parse_static_routes_single_ip(self):
+        rfc3442 = "32,169,254,169,254,130,56,248,255"
+        self.assertEqual([('169.254.169.254/32', '130.56.248.255')],
+                         parse_static_routes(rfc3442))
+
+    def test_parse_static_routes_single_ip_handles_trailing_semicolon(self):
+        rfc3442 = "32,169,254,169,254,130,56,248,255;"
+        self.assertEqual([('169.254.169.254/32', '130.56.248.255')],
+                         parse_static_routes(rfc3442))
+
+    def test_parse_static_routes_default_route(self):
+        rfc3442 = "0,130,56,240,1"
+        self.assertEqual([('0.0.0.0/0', '130.56.240.1')],
+                         parse_static_routes(rfc3442))
+
+    def test_parse_static_routes_class_c_b_a(self):
+        class_c = "24,192,168,74,192,168,0,4"
+        class_b = "16,172,16,172,16,0,4"
+        class_a = "8,10,10,0,0,4"
+        rfc3442 = ",".join([class_c, class_b, class_a])
+        self.assertEqual(sorted([
+            ("192.168.74.0/24", "192.168.0.4"),
+            ("172.16.0.0/16", "172.16.0.4"),
+            ("10.0.0.0/8", "10.0.0.4")
+        ]), sorted(parse_static_routes(rfc3442)))
+
+    def test_parse_static_routes_logs_error_truncated(self):
+        bad_rfc3442 = {
+            "class_c": "24,169,254,169,10",
+            "class_b": "16,172,16,10",
+            "class_a": "8,10,10",
+            "gateway": "0,0",
+            "netlen":  "33,0",
+        }
+        for rfc3442 in bad_rfc3442.values():
+            self.assertEqual([], parse_static_routes(rfc3442))
+
+        logs = self.logs.getvalue()
+        self.assertEqual(len(bad_rfc3442.keys()), len(logs.splitlines()))
+
+    def test_parse_static_routes_returns_valid_routes_until_parse_err(self):
+        class_c = "24,192,168,74,192,168,0,4"
+        class_b = "16,172,16,172,16,0,4"
+        class_a_error = "8,10,10,0,0"
+        rfc3442 = ",".join([class_c, class_b, class_a_error])
+        self.assertEqual(sorted([
+            ("192.168.74.0/24", "192.168.0.4"),
+            ("172.16.0.0/16", "172.16.0.4"),
+        ]), sorted(parse_static_routes(rfc3442)))
+
+        logs = self.logs.getvalue()
+        self.assertIn(rfc3442, logs.splitlines()[0])
+
+
 class TestDHCPDiscoveryClean(CiTestCase):
     with_logs = True
 
diff --git a/cloudinit/net/tests/test_init.py b/cloudinit/net/tests/test_init.py
index 6d2affe..d393e6a 100644
--- a/cloudinit/net/tests/test_init.py
+++ b/cloudinit/net/tests/test_init.py
@@ -549,6 +549,45 @@ class TestEphemeralIPV4Network(CiTestCase):
             self.assertEqual(expected_setup_calls, m_subp.call_args_list)
         m_subp.assert_has_calls(expected_teardown_calls)
 
+    def test_ephemeral_ipv4_network_with_rfc3442_static_routes(self, m_subp):
+        params = {
+            'interface': 'eth0', 'ip': '192.168.2.2',
+            'prefix_or_mask': '255.255.255.0', 'broadcast': '192.168.2.255',
+            'static_routes': [('169.254.169.254/32', '192.168.2.1'),
+                              ('0.0.0.0/0', '192.168.2.1')],
+            'router': '192.168.2.1'}
+        expected_setup_calls = [
+            mock.call(
+                ['ip', '-family', 'inet', 'addr', 'add', '192.168.2.2/24',
+                 'broadcast', '192.168.2.255', 'dev', 'eth0'],
+                capture=True, update_env={'LANG': 'C'}),
+            mock.call(
+                ['ip', '-family', 'inet', 'link', 'set', 'dev', 'eth0', 'up'],
+                capture=True),
+            mock.call(
+                ['ip', '-4', 'route', 'add', '169.254.169.254/32',
+                 'via', '192.168.2.1', 'dev', 'eth0'], capture=True),
+            mock.call(
+                ['ip', '-4', 'route', 'add', '0.0.0.0/0',
+                 'via', '192.168.2.1', 'dev', 'eth0'], capture=True)]
+        expected_teardown_calls = [
+            mock.call(
+                ['ip', '-4', 'route', 'del', '0.0.0.0/0',
+                 'via', '192.168.2.1', 'dev', 'eth0'], capture=True),
+            mock.call(
+                ['ip', '-4', 'route', 'del', '169.254.169.254/32',
+                 'via', '192.168.2.1', 'dev', 'eth0'], capture=True),
+            mock.call(
+                ['ip', '-family', 'inet', 'link', 'set', 'dev',
+                 'eth0', 'down'], capture=True),
+            mock.call(
+                ['ip', '-family', 'inet', 'addr', 'del',
+                 '192.168.2.2/24', 'dev', 'eth0'], capture=True)
+        ]
+        with net.EphemeralIPv4Network(**params):
+            self.assertEqual(expected_setup_calls, m_subp.call_args_list)
+        m_subp.assert_has_calls(expected_setup_calls + expected_teardown_calls)
+
 
 class TestApplyNetworkCfgNames(CiTestCase):
     V1_CONFIG = textwrap.dedent("""\
diff --git a/tests/unittests/test_datasource/test_azure.py b/tests/unittests/test_datasource/test_azure.py
index f27ef21..2de2aea 100644
--- a/tests/unittests/test_datasource/test_azure.py
+++ b/tests/unittests/test_datasource/test_azure.py
@@ -1807,7 +1807,8 @@ class TestAzureDataSourcePreprovisioning(CiTestCase):
         self.assertEqual(m_dhcp.call_count, 2)
         m_net.assert_any_call(
             broadcast='192.168.2.255', interface='eth9', ip='192.168.2.9',
-            prefix_or_mask='255.255.255.0', router='192.168.2.1')
+            prefix_or_mask='255.255.255.0', router='192.168.2.1',
+            static_routes=None)
         self.assertEqual(m_net.call_count, 2)
 
     def test__reprovision_calls__poll_imds(self, fake_resp,
@@ -1845,7 +1846,8 @@ class TestAzureDataSourcePreprovisioning(CiTestCase):
         self.assertEqual(m_dhcp.call_count, 2)
         m_net.assert_any_call(
             broadcast='192.168.2.255', interface='eth9', ip='192.168.2.9',
-            prefix_or_mask='255.255.255.0', router='192.168.2.1')
+            prefix_or_mask='255.255.255.0', router='192.168.2.1',
+            static_routes=None)
         self.assertEqual(m_net.call_count, 2)
 
 
diff --git a/tests/unittests/test_datasource/test_ec2.py b/tests/unittests/test_datasource/test_ec2.py
index 20d59bf..1ec8e00 100644
--- a/tests/unittests/test_datasource/test_ec2.py
+++ b/tests/unittests/test_datasource/test_ec2.py
@@ -538,7 +538,8 @@ class TestEc2(test_helpers.HttprettyTestCase):
         m_dhcp.assert_called_once_with('eth9')
         m_net.assert_called_once_with(
             broadcast='192.168.2.255', interface='eth9', ip='192.168.2.9',
-            prefix_or_mask='255.255.255.0', router='192.168.2.1')
+            prefix_or_mask='255.255.255.0', router='192.168.2.1',
+            static_routes=None)
         self.assertIn('Crawl of metadata service took', self.logs.getvalue())