Fix eni rendering of multiple IPs per interface

The iface:alias syntax for eni rendering is brittle with ipv6.
Replace it with using multiple iface stanzas with the same iface
name which is supported.  Side-effect is that one can no longer
do 'ifup $iface:$alias' but requires instead use of ip address
{add|delete} instead.

LP: #1657940

2 files changed, 53 insertions, 26 deletions

diff --git a/cloudinit/net/eni.py b/cloudinit/net/eni.py
index b06ffac9..5b249f1f 100644
--- a/cloudinit/net/eni.py
+++ b/cloudinit/net/eni.py
@@ -90,8 +90,6 @@ def _iface_add_attrs(iface, index):
 
 def _iface_start_entry(iface, index, render_hwaddress=False):
     fullname = iface['name']
-    if index != 0:
-        fullname += ":%s" % index
 
     control = iface['control']
     if control == "auto":
@@ -113,6 +111,16 @@ def _iface_start_entry(iface, index, render_hwaddress=False):
     return lines
 
 
+def _subnet_is_ipv6(subnet):
+    # 'static6' or 'dhcp6'
+    if subnet['type'].endswith('6'):
+        # This is a request for DHCPv6.
+        return True
+    elif subnet['type'] == 'static' and ":" in subnet['address']:
+        return True
+    return False
+
+
 def _parse_deb_config_data(ifaces, contents, src_dir, src_path):
     """Parses the file contents, placing result into ifaces.
 
@@ -354,21 +362,23 @@ class Renderer(renderer.Renderer):
         sections = []
         subnets = iface.get('subnets', {})
         if subnets:
-            for index, subnet in zip(range(0, len(subnets)), subnets):
+            for index, subnet in enumerate(subnets):
                 iface['index'] = index
                 iface['mode'] = subnet['type']
                 iface['control'] = subnet.get('control', 'auto')
                 subnet_inet = 'inet'
-                if iface['mode'].endswith('6'):
-                    # This is a request for DHCPv6.
-                    subnet_inet += '6'
-                elif iface['mode'] == 'static' and ":" in subnet['address']:
-                    # This is a static IPv6 address.
+                if _subnet_is_ipv6(subnet):
                     subnet_inet += '6'
                 iface['inet'] = subnet_inet
-                if iface['mode'].startswith('dhcp'):
+                if subnet['type'].startswith('dhcp'):
                     iface['mode'] = 'dhcp'
 
+                # do not emit multiple 'auto $IFACE' lines as older (precise)
+                # ifupdown complains
+                if True in ["auto %s" % (iface['name']) in line
+                            for line in sections]:
+                    iface['control'] = 'alias'
+
                 lines = list(
                     _iface_start_entry(
                         iface, index, render_hwaddress=render_hwaddress) +
@@ -378,11 +388,6 @@ class Renderer(renderer.Renderer):
                 for route in subnet.get('routes', []):
                     lines.extend(self._render_route(route, indent="    "))
 
-                if len(subnets) > 1 and index == 0:
-                    tmpl = "    post-up ifup %s:%s\n"
-                    for i in range(1, len(subnets)):
-                        lines.append(tmpl % (iface['name'], i))
-
                 sections.append(lines)
         else:
             # ifenslave docs say to auto the slave devices
diff --git a/tests/unittests/test_net.py b/tests/unittests/test_net.py
index 2c2bde96..b77d277a 100644
--- a/tests/unittests/test_net.py
+++ b/tests/unittests/test_net.py
@@ -219,11 +219,9 @@ NETWORK_CONFIGS = {
 
             auto eth99
             iface eth99 inet dhcp
-                post-up ifup eth99:1
 
-
-            auto eth99:1
-            iface eth99:1 inet static
+            # control-alias eth99
+            iface eth99 inet static
                 address 192.168.21.3/24
                 dns-nameservers 8.8.8.8 8.8.4.4
                 dns-search barley.maas sach.maas
@@ -261,6 +259,27 @@ NETWORK_CONFIGS = {
                     - wark.maas
         """),
     },
+    'v4_and_v6': {
+        'expected_eni': textwrap.dedent("""\
+            auto lo
+            iface lo inet loopback
+
+            auto iface0
+            iface iface0 inet dhcp
+
+            # control-alias iface0
+            iface iface0 inet6 dhcp
+        """).rstrip(' '),
+        'yaml': textwrap.dedent("""\
+            version: 1
+            config:
+              - type: 'physical'
+                name: 'iface0'
+                subnets:
+                - {'type': 'dhcp4'}
+                - {'type': 'dhcp6'}
+        """).rstrip(' '),
+    },
     'all': {
         'expected_eni': ("""\
 auto lo
@@ -298,11 +317,9 @@ iface br0 inet static
     address 192.168.14.2/24
     bridge_ports eth3 eth4
     bridge_stp off
-    post-up ifup br0:1
-
 
-auto br0:1
-iface br0:1 inet6 static
+# control-alias br0
+iface br0 inet6 static
     address 2001:1::1/64
 
 auto bond0.200
@@ -319,11 +336,9 @@ iface eth0.101 inet static
     mtu 1500
     vlan-raw-device eth0
     vlan_id 101
-    post-up ifup eth0.101:1
-
 
-auto eth0.101:1
-iface eth0.101:1 inet static
+# control-alias eth0.101
+iface eth0.101 inet static
     address 192.168.2.10/24
 
 post-up route add -net 10.0.0.0 netmask 255.0.0.0 gw 11.0.0.1 metric 3 || true
@@ -758,6 +773,13 @@ class TestEniRoundTrip(CiTestCase):
             entry['expected_eni'].splitlines(),
             files['/etc/network/interfaces'].splitlines())
 
+    def testsimple_render_v4_and_v6(self):
+        entry = NETWORK_CONFIGS['v4_and_v6']
+        files = self._render_and_read(network_config=yaml.load(entry['yaml']))
+        self.assertEqual(
+            entry['expected_eni'].splitlines(),
+            files['/etc/network/interfaces'].splitlines())
+
     def test_routes_rendered(self):
         # as reported in bug 1649652
         conf = [